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Fourth International Symposium on
Irrigation of Horticultural Crops
ISHS
International Society for Horticultural Science
Program
and
Book of Abstracts
1-5 September 2003
University of California
Davis, California
1
Development of a Fully Automated Microirrigation System on the base of
Climatic Water Balance and TDR Measurements
Aguila, F.M., H. Sinn and S. Kleisinger
Institute of Agricultural Engineering (440)
University of Hohenheim
70599 Stuttgart, Germany
Abstract
A fully automated microirrigation system was developed, that used real time
irrigation data to optimize water application efficiency by means of climatic water
balance and TDR measurements. The automated irrigation program was written in
Edlog and incorporated with a CR10X-Campbell Scientific datalogger. In order to get
meteorological data, an in-situ weather station was installed to calculate hourly
Penman-Monteith ETo. A polynomial crop coefficient curve was used to have a better
approximation of the real plant development to calculate ETc. Water balance of the
root zone was calculated by using a root depth curve. Depletion fraction values were
adjusted by relating to phenological stages to enable significant reduction of irrigation
in non-sensitive phases. Automated hourly water content measurements were possible
by direct connection of TDR sensors to the datalogger. On-line monitoring was
established by using internet connection. The automated irrigation program was
employed to calculate the adequate irrigation time and quantity, and to control the
microirrigation field. The microirrigation system was tested in an experimental field
with pumpkin under Supernet-Netafim microsprinkler. Three different irrigation
strategies were realized by considering plant model, without considering plant model
and considering only TDR measurements. The results indicated that the irrigation
system worked reliable. Differences in water use efficiency and production yield in
dependence the irrigation strategy could be worked out.
2
Application of Soil Fumigants through Drip Irrigation Systems
Husein Ajwa
University of California
Tom Trout
USDA-ARS
Abstract
Soils are fumigated before planting several high-valued horticultural crops to
reduce disease and pest pressures. The scheduled phase-out of methyl bromide (MeBr)
has stimulated considerable research to identify alternative fumigants and to evaluate
application techniques for pre-plant soil fumigation. For uniform distribution of
alternative fumigants, applications with irrigation water through drip irrigation
systems may be a more effective method than conventional shank injection into soil in
raised-bed culture. Water-soluble formulations of soil fumigants (such as 1,3dichloropropene, chloropicrin, metham sodium, and iodomethane) can be applied
through the drip irrigation systems that are used to irrigate crops. Our research has
focused on developing and optimizing drip fumigation techniques for various soil types
and under different configurations of drip irrigation systems. Our studies found that
higher amounts of irrigation water would result in greater fumigant concentration in
the gas phase across the soil profile. Factors affecting water distribution around a drip
line include soil hydraulics (water holding capacity and unsaturated hydraulic
conductivity, initial soil water content, etc.), water application rate, drip system
specification (emitter spacing and distance between the drip lines), and soil bed
configuration (height and width of the bed). Drip fumigation is economical, reduces
worker exposure, and can be environmentally friendly and reduce the amount of
chemicals applied. Drip-applied fumigants are now registered and are being
commercially applied in the U.S.A.
3
Effect of planting date and irrigation water level on onion (Alium cepa L.)
productivity under Central Saudi Arabian conditions
A. M. Al-Moshileh
Department of Plant Production and Protection,
College of Agriculture and Veterinary Medicine, King Saud University,
Al-Qassim, Saudi Arabia
Keywords: Onion, Allium cepa, production, irrigation level, vegetative growth, Planting
date, Harvesting period, Bulb yield.
Abstract
The effects of four planting dates and three water quantity applications, on
onion growth and production, were studied under sandy soil habitat at a semi-arid
condition of Al-Qassim region, Central Saudi Arabia during 2000/2001 and 2001/2002
autumn seasons. The early planting dates showed significantly higher growth values
than the later planting dates in the two growing seasons. Also, as onion seeds were sown
early, total bulb yield increased, but plants tended to produce more flower stalks and
doubled bulbs than late planting date. The applied water level had a significant effect
on the growth of onion plants. As soil water supply increased, plant growth parameters
and total yield were significantly increased, while marketable yield was reduced.
4
Irrigation Efficiency Applying Subsurface
Minisprinkler Irrigation on Potato Crop
Drip
Irrigation
and
Anconelli S., Guidoboni G. and Battilani, A.
Abstract
The trial was carried out in the Po Valley (Northern Italy), in a sub-humid area
from 1999 to 2001. The experimental schema was as follows:
Rainfed
Mini-sprinkler irrigation (flow rate 150 l/h), 50% ETc.
Mini-sprinkler irrigation ( flow rate 150 l/h), 100% ETc.
Subsurface drip irrigation, 50% ETc.
Subsurface drip irrigation, 100% ETc.
The irrigation has increased the marketable yield of 23% respect to the rainfed (P =
0.01). There was no significant difference between the methods, however the yield with
drip irrigation resulted a little more higher both with an ETc replenishment of 50% and
100%. As a consequence, the Water Use Efficiency (WUE) was found very similar
between methods. The full replenishment of the ETc has no significant effect on the
marketable yield (+6% respect to the 50% ETc treatments). Subsurface drip irrigation
increased the tuber dry matter and starch content, although in a non statistically
significant way: the amount of tuber dry matter produced per hectar resulted higher in
the 50% ETc respect to the Mini-sprinkler/100 % ETc treatment. Irrigation has
increased the tuber’s size respect to the rainfed P = 0.01): in particular applying the
Subsurface drip irrigation the percentage of tuber in the 60-75 mm class result higher
respect to those obtained using the Mini-sprinkler.
5
Persistence and Mobility of Malathion and Parathion in Horticultural
Semiarid Soils
M.L. Andrade 1, M.L. Reyzábal 2and P. Marcet 1
1Departamento de Biología Vegetal y Ciencia del Suelo. Universidad de Vigo. 36200
Vigo. España. e-mail: [email protected]. Tel: 986 812630, Fax: 986 812556.
2Departamento de Agronomía. Universidad Nacional del Sur. Altos de Palihue. 8000
Bahía Blanca. Argentina.
Abstract
In order to verify whether soils of different ages used for horticulture show the
effects of applying pesticides (Malathion and Parathion), the persistence of these
compounds at different depths in the soil profile and their mobility have been analyzed.
An alkaline soil pH, amongst other factors, favours the degradation of the
organophosphorus pesticides, but this is not sufficient to compete with annual
applications repeated over a period of five decades. The highest values are found in the
soils that have been cultivated for more than fifty years and the highest content at a
depth from 0-5 cm, which indicates their low level of mobility. In soils that have
received large amounts of these products over this period of time, they are found at all
levels of the soil profile. The relative mobility of Malathion and Parathion depends
more on their properties and the time that the land has been dedicated to intensive
horticultural cultivation, than on the physicochemical properties of the soil or of the
crop. The oldest field showed the highest values, confirming their accumulation over
time and their persistence due to the absence of biological degradation. The results
indicate that these insecticides are immobile under semiarid conditions and show a
relative adsorption in the soil particles.
6
Challenges of Conducting Salt Tolerance Studies under Field Conditions
R. Aragüés
Agronomic Research Service
Government of Aragón
Zaragoza (Spain)
Abstract
Establishing the salt tolerance of crops is important both from the economic (i.e.,
selection of the most productive and financially attractive crops for a given soil salinity)
and the environmental (i.e., attaining the proper salt balance for required leaching
while minimizing off-site pollution effects) viewpoints. These evaluations should
preferably be performed under real field conditions because of the ambient-dependency
of salt tolerance. However, these studies are a challenge for researchers due to the many
potential factors affecting the results. Among others, these studies are complicated by
the inherent temporal and spatial variability of soil salinity, and by the existence of
other undetermined crop stresses. After summarizing important factors affecting salt
tolerance, the first part of this presentation describes an approach for the precise
determination of soil salinity variability and an effective design for tolerance trials. The
approach is based on geo-referenced electromagnetic readings of apparent soil salinity
followed by the delineation of salinity contour maps. The crops under evaluation are
then grown along the maximum salinity gradient in order to cover a wide range of
“ECe-Yield” observations. These observations are then fitted to the most appropriate
salt-tolerance response model. The second part of this presentation summarizes a 3-year
evaluation of young olive trees (Olea europaea L., cv. Arbequina) grown in a saltaffected irrigated field where soil sodicity, waterlogging and a shallow, saline watertable
were also present. The establishment of olive’s salt tolerance with these additional
stresses is rather complicated since they were auto-correlated. The approach of the
“upper envelope eye-fitting” of the salinity-growth observations to the classical Maas
and Hoffman model was used trying to circumvent these difficulties. The salinity
tolerance of young olive trees decreased by more than 50% during the study period,
indicating a decline in tolerance with age and time of exposure to salts.
7
Use of Numerical Weather Forecast and Time Series Models for Predicting
Reference Evapotranspiration
Michele Fiori
Agrometeorological Regional Service of
Sardinia
Sassari, Italy
Bachisio Arca
Pierpaolo Duce
Institute of Biometeorology
CNR-IBIMET
Sassari, Italy
Donatella Spano
Department of Economics and Woody
Plant Ecosystems
University of Sassari
Sassari, Italy
Richard L. Snyder
Department of Land, Air and Water
Resources
Davis, CA
USA
Abstract
Providing forecast of water balance components such as evapotranspiration,
precipitation and runoff is important for water management and irrigation scheduling.
Reference evapotranspiration (ETo) prediction will greatly enhance our capability to
manage the irrigation of high-frequency irrigation systems and shallow-rooted crops.
Several mathematical and statistical methods can be used to forecast ETo. Reference
evapotranspiration values can be calculated using analytical models (Penman-Monteith,
Penman, etc.) and meteorological forecasts from numerical weather prediction models.
Other methods are based on the time series analysis of ETo and meteorological
variables related to evapotranspiration process. The autoregressive integrated moving
average (ARIMA) models are the most frequently used time series models. Moreover,
artificial neural networks (ANN) have been recently applied in time series modeling and
forecasting. The main aims of this study are to analyze and compare the performance of
the above-mentioned techniques in short-term prediction of hourly and daily ETo.
Hourly values of ETo were calculated using the Penman-Monteith equation and hourly
weather data from a mesoscale forecast model (BOLAM) provided by the
Agrometeorological Service of Sardinia (SAR), Italy. Both ARIMA and ANN models
were developed using eight years of meteorological data from five meteorological
stations of SAR. Each method was validated using a one-year data set from five
locations. The accuracy of prediction from each method was evaluated comparing the
forecasts with ETo values calculated using observed weather data from SAR weather
stations. The 12, 24, and 36 hour predictions of hourly ETo values from weather
variables forecast gave a root mean square error value of about 0.11-0.16 mm h-1 with
an overestimation ranging from 3% to 6%. Better results were obtained from the time
series model based on ANN, especially when time series of meteorological data were
provided in addition to reference evapotranspiration data . ARIMA seasonal models
showed the worst accuracy.
8
Regulated Deficit of Irrigation (RDI) effects on Growth and Yield of Plum
Tree
Battilani, A.
Abstract
A field experiment was performed to study the response of Plum cv. Fortune to
different water regimes and strategies. The aim of the trial, carried out in the years
1995-2002, was to identify the most suitable irrigation regimes and to test the
effectiveness of the RDI techniques in a sub-humid area and on a fruit crop frequently
not irrigated in the region. The treatments in comparison were: Rainfed; 50% and
100% of ETc; 100% ETc applying RDI in DW2a and DW4 and an extended RDI
(RDI/A) in which the stress was applied during the phases DW2a, DW2b, DW4. The
irrigation increased significantly the yield respect to the rainfed (+6.94 t ha-1;28.6 %).
The yield increase was related to the higher number of fruit and fruit average weight in
the irrigated treatments. The gross margin (average 95-02) increase of 4354 euro ha-1 y-1
(40.8%). Among the irrigated treatment the RDI ones was no different from the 100%
ETc. The 50% ETc results in a great uncertainty in the yield level and quality, strongly
related to the rain distribution. RDI has no effect on the vegetative growth, which result
similar to those observed in the 100% ETc and higher than rainfed. The ratio
yield/TCSA (trunk cross section area), assumed as an index of efficiency of the plant,
was higher with 100% ETc, RDI and RDI/A than 50% ETc and rainfed. The water use
efficiency (WUE) decrease from rainfed to 100% ETc. Among the irrigated treatments,
WUE results better applying the RDI techniques. The application of RDI reduces the
water supply of about 40.0 % respect to 100% ETc. The results shown that it is possible
to obtain a good yield, quality, and profits supplying in the average 160 mm y-1 of
irrigation water.
9
Water Table Level Effect on the Water Balance and Yield of two Pear
Rootstock
Battilani A., Anconelli S. and Guidoboni G.
Abstract
The trial was carried out in the years 1994-2002 in the Po Valley (Northern
Italy). The orchard, cv Conference grafted on Quince-C and self rooted and Williams
self rooted, was planted on an experimental field featured a slope of 1.6% and with an
artificial water table (WT) maintained at a depth of 90 cm in the bottom part of the
field and 250 cm in the upper one. The aim of the trial was to define the effect of the
water table on the pear tree growth and yield and to estimate the potential contribution
of the capillary rising to the water balance. The fruit quality was not related to the
water table depth, neither the trunk circumference, the canopy volume and the weight
of pruning wood. The growth ratio of the canopy start to decrease from 190 cm WT for
Conference/Quince-C, 240 cm WT for Conference self rooted and there is no effect on
Williams self rooted. The marketable yield shows a strong negative relationship with
shallow and deep water table. The curve inflexion point correspond to a water table
depth of 155 cm. In general the yield decrease faster with a decrease of the WT (water
excess) than with a WT increase, even if the yield reduction caused by the water
deficiency results higher. Conference/Quince-C show a yield reduction of 20% respect
to the maximum observed yield in case of water excess and of 72% in case of deficiency.
The reduction was respectively of 16% and 40% for Conference self rooted and not
relevant for Williams self rooted. Water table contribution to the water balance was
often more than the daily ETc with WT less than 120 cm, the WT contribution decrease
rapidly at a depth more than 150-160 cm.
10
Potato’s efficient use of water and nitrogen in a sub-humid area
Battilani A., Dalla Costa L. and Lovatti L.
Abstract
The rational use of the natural resources, especially water and nutrients, is one
of the most important topics in the sustainable management of cropping systems. To
achieve this goal it is useful reasoning about some efficiency indexes in order to optimise
the water and nitrogen crop scheduling. The water and nitrogen use efficiency (WUE
and NUE) were calculated from the results of a lysimeter experiment in which a well
water drip irrigation control (100% ETc ) was compared with a treatment saturated at
the beginning of the experiment and no longer irrigated. Thus the water stress is
imposed only during the tuber enlargement and not during the tuberisation phase. In a
field experiment the effects of three treatments (rainfed, 100% ETc, 100%/70% ETc
with a change of irrigation regime at a tuber average diameter of 35 mm) on four
varieties (one determinate and three not determinate) were compared. In the field WUE
decrease respect to rainfed from 75% to 48% according to the rain distribution during
the growth cycle, either calculated on the fresh matter or on the dry matter. The NUE
was found related to water availability and increase till 48% with 100%ETc. Some
difference was found for the varieties, especially for the determinate one. The indexes
calculated in the field trial experiment was compared with those calculated from the
lysimeter observations.
11
Modeling Actual Evapotranspiration of Ligustrum japonica from Rooted
Cuttings to Commercially Marketable Plants in 11 Liter Black
Polyethylene Containers
RC. Beeson, Jr.
Univ. of Florida, MREC,
2725 S. Binion Road
Apopka, FL 32703 USA
Abstract
Nursery production of woody landscape ornamentals has shifted the past 40
years to predominately container production for small to medium size shrubs and trees.
While nurseries occupy relatively small land areas compared to agronomic crops, their
consumption of water is quite high, ranging between 1.8 to 3.1 m annually in the
Southeastern US. Irrigation frequency and quantity is almost always based personal
experience, and increasingly delegated to automated systems. Plant water use can vary
greatly from day to day, across seasons, and with plant growth. Seldom are these
changes quickly detected by irrigation managers, resulting in over and under
applications of irrigation. In agronomic crops, models that incorporate Reference
Evapotranspiration (ETref) and crop size function well for predicting irrigation
requirements. Plant water use for maximum growth is highly correlated with ETref. In
order to increase irrigation precision for nursery crops, similar models must be
developed. A model that predicts Actual Evapotranspiration for Ligustrum japonica
based on ETref and canopy size will be presented. This model was derived during the
production of rooted cuttings to commercial market size plants in 11 liter containers
under a simulated nursery production situation. With knowledge of local ETref and
canopy size, use of this model would permit more accurate and timely changes in
irrigation application during container production and water conservation.
12
Improvements in Application Efficiency of Overhead Sprinkler Irrigated
Container Grown Woody Ornamentals
R.C. Beeson, Jr. And J.J. Haydu
Univ. of Florida, MREC
2725 S. Binion Road
Apopka, FL 32703
USA
J. Caron
Dept. des Sols et de génie agroalimentaire
Université Laval
Ste. Foy, Quebec, G1K 7P4
CANADA
Abstract
Overhead sprinkler irrigation systems of woody landscape plants, grown in
containers at commercial production spacing, normally have application efficiencies of
15 to 30%. Thus 70 to 85% or more of the water applied to a production area is
unavailable to the crop and wasted. This is due primarily to the large open spaces
between containers, necessitated by the small container surface area to canopy surface
area ratios. Systems, either currently available in North America or under commercial
development between 1999 to 2001, were evaluated for water conservation using
overhead sprinkler irrigation and their ability to produce commercial quality plants in
a reasonable amount of time. Several of these systems increased application efficiency,
and reduced the volume of required overhead irrigated water by 50% to 75%,
compared to unmodified overhead sprinkler irrigated areas. These systems and
supporting data will be presented.
13
Irrigation management to optimize olive oil production and quality
M. J. Berenguer-Merelo, S.R. Grattan, J.H. Connell, V.S. Polito, P.M.Vossen
Abstract
Irrigation management has a profound influence on both olive production and
oil quality. In order to optimize oil production and quality, we initiated a study in the
Spring of 2002 to identify the optimal level of applied water on a super-high-density
(tree spacing 1.5 m by 3.9 m) orchard of ‘Arbequina’ olives. Irrigation water was
applied differentially by drip irrigation to produce treatments of 15, 25, 40, 57, 71, 89,
and 107% ET calculated from weather station ETo values and crop coefficients
adjusted for changing canopy coverage. The experiment consisted of three replicated
blocks. Tree growth was monitored by changes in trunk diameter and branch length.
Final branch lengths of those from the two most water deprived treatments were half or
less of those from the two highest irrigation treatments. Mid-day stem water potentials
were measured periodically throughout the season and values ranged between –6 and 30 bars and differences were consistent with the irrigation treatments. Fruits were
harvested at two different times (31 Oct. and 18 Nov) to evaluate treatment effect in
relation to harvest date. At each harvest, fruit production (kg/tree) was related
(r2=0.84) to the natural log (ln) of the applied water. Delaying harvest slightly increased
fruit production, regardless of irrigation treatment. Olive oil was extracted using the
Abencor apparatus and the percentage of oil in the fruit decreased linearly (r2=0.95)
with increased applied water. The overall quantity of oil produced per tree, on the other
hand, followed a second order function (r2=0.59 and 0.76) with a maximal quantity
achieved between the 57 and 71% ET treatments. Wetter and dryer treatments
produced less oil per tree. The date of harvest did not influence this zone of maximal oil
production. Sensorial and chemical quality characteristics of the oil will be determined.
14
FAO activities to develop agro-climatic datasets and tools for the needs of
irrigation management
Michele Bernardi
Environment and Natural Resources Service
Food and Agriculture Organization of the United Nations
Viale delle Terme di Caracalla
00100 Rome, Italy
Keywords: Agro-meteorology, agro-climatic data and software, digital datasets, irrigation
planning and management, decision support tools.
Abstract
The improvement of irrigated crop system management has become a priority
for economic and environmental reasons. In many cases, irrigation control is mainly a
question of management of: water resources, equipment and manpower. It therefore
depends on choices to define the water supply strategies for optimal crop production
and economic returns under conditions of reduced water supply and to advise farmers
to optimize timing and application rate of crop irrigation for optimal yields and income
also under limited water supply. The choice of cropping plan stands on farm
constraints: (i) crops to irrigate, production and margin objectives; (ii) irrigation
programme, i.e. a set of decision-making rules concerning irrigation management. To
define the best strategy, the irrigation programme is elaborated taking account of: the
agronomic parameters of each crop, the soils and climate characteristics and,
particularly, climate variability. However, the accuracy of these strategies is often
limited by the availability of climatic data at a specific temporal or spatial resolution
and by the availability of adequate crop information for regional applications. These
are just few examples of the problems to deal with in the planning and operational
activities related to the irrigation management. To minimize the impact of such a
problems, the Food and Agriculture Organization of the United Nations (FAO) has
developed application tools to avoid the lack of agro-climatic data at worldwide level.
FAO is a specialized UN Agency dealing with agriculture, forestry and fishery,
particularly in developing countries. One of its technical services has the responsibility
to provide information on environment and natural resources as related to food and
agriculture and it includes, among others, expertise in remote sensing and GIS. The
Agro-meteorology Group is part of this service and it is responsible to provide global
environmental digital datasets, to collect meteorological data in real-time, to develop
methodologies, models and tools for data standardization, collection, spatialization and
analysis. Data and tools are developed taking into account technical specifications of
decision support systems for irrigation planning and management developed by other
FAO services.
15
Oxygenation of rhizosphere by aerated water and hydrogen peroxide
injection through subsurface drip irrigation improves water use efficiency
and yield of vegetable soybean
S. P. Bhattarai1 and D. J. Midmore
Plant Sciences Group
School of Biological and Environmental Sciences
Central Queensland University
Rockhampton, QLD 4702
Australia
Keywords: Aeration of root zone, vegetable soybean, sub surface drip irrigation, water use
efficiency, hydrogen peroxide.
Abstract
Low oxygen concentration of rhizosphere is a common manifestation
particularly in heavy clay soils that are saturated, compacted and/or saline. It exerts
severe consequences on plants performance. Sub surface drip irrigated (SDI) crop in
heavy clay soils frequently experience oxygen deprivation particularly at higher rate of
irrigation. Pot experiment was carried out on vegetable soybean (Glycine max L.
Merrill) to investigate the effect of hydrogen peroxide (HP) and air injection through
SDI tape as means of oxygen supplement to roots in heavy clay soil at field capacity and
saturation. HP (50 % v/v) was mixed @ 1 ml/l water whereas air injection was achieved
by Mazzei TM air injector model 484 which allows mixing air @ of 12 percent by
volume of water, and supplied throughout the irrigation cycle. Increased aeration of
root zone with air and HP injection through SDI significantly increased fresh pod yield
and water use efficiency (WUE) compared to that of control. An increase in number of
pods per plant, and mean pod weight were associated with the higher yield. The
increase in yield was 96 and 82 percent and an increase in WUE was 72 and 55 percent
due to air injection and HP injection respectively compared to control. The higher yield
and WUE is attributed to increased soil respiration and leaf photosynthetic rate. Hence,
increased aeration of rhizosphere through SDI on vegetable soybean in heavy clay soils
can provide benefits in terms of yield and WUE.
1
Corresponding author: Tel: +61 07 49232050; Fax: +61 07 49309255
E-mail address: [email protected]
16
Physiological and productive characteristics of Sangiovese grapevine as
affected by Regulated Deficit Irrigation
Maurizio Boselli and Giovan Battista Mattii
Department of Horticulture, University of Florence,
Viale delle Idee, 30
50019 Sesto Fiorentino (FI)
Italy
Abstract
Water is an extremely scarce resource in South Tuscany (Italy). Precipitation is
mostly insufficient to meet grapevines requirements. The key to improving wine grape
quality is to achieve an appropriate balance between vegetative and reproductive
development since an excess of shoot vigor may have undesirable consequences for fruit
composition. The deliberate withholding of irrigation water may therefore be an
important management strategy to affect crop water use and plant balance and this is
embodied in the technique known as RDI (Regulated Deficit Irrigation). The decision to
initiate irrigation each growing season depends on several factors and in many
vineyards is often based upon empirical criteria. In this research, we based our choice
upon predawn leaf water potential. Three levels of RDI by drip irrigation were applied:
75%, 50% and 25 % of full Etc. Potential ET has been calculated by FAO PenmanMonteith. Ecophysiological behavior as well as productive characteristics as affected by
different RDI were observed. Measurements of leaf water potential using a pressure
chamber at different time of the day within the season were performed. In the same
days single leaf photosynthesis, transpiration, and stomatal conductance were also
performed by an infra red gas analyzer Ciras 1, as well as chlorophyll content using a
SPAD device. After veraison, analyses on must main qualitative characterisitcs have
been conducted: total soluble solids, titratable acidity and pH; analyses on skin
polyphenols were also carried out. At harvest plant production as well as cluster weight
were detected. Useful information about the effect of irrigation on the main productive
and physiological Sangiovese behavior were achieved and discussed.
17
New Intensive Capillary Hydroponic System
Brizuela-Amador P., B., G. Alcántar González, P. Sánchez-García and M.
Sandoval-Villa
Programa de Edafología, IRENAT
Colegio de Postgraduados
Montecillo. km. 36.5 Carr.
México-Texcoco Montecillo, México
MÉXICO 56230
L. Tijerina-Chávez
Programa de Hidrociencias. IRENAT,
Colegio de Postgraduados, km. 36.5 Carr.
México-Texcoco, Montecillo, México,
MÉXICO 56230
Abstract
Agricultural food production faces lack and poor water quality, extreme
temperatures, land degradation, energy deficit, and peasants migration. A social and
technical solution to this problem is the intensification of agriculture by growing plants
under greenhouse combined with high plant populations by using hydroponic systems.
It is proposed a new hydroponic system called “Intensive Capillary Hydroponic
System”. It presents a high capacity to buffer temperature and water vapor pressure
deficit, requires little energy and can be used to grow vegetables, small bushes,
medicinal plants and species. The system consists of a 20 L black polyiethylene or PVC
tubes filled with substrate. Tubes are half longitudinally embedded in a nutrient
solution with a osmotic pressure of 0.072 MPa. The solution is placed into 1.2 x 1.4 m
container covered by black polyiethylene caliber 400 and a UVII 720 caliber plastic is
used to build a 1.5 m height tunnel. Infra-red lamps are used to heat the tunnel.
Sensible temperatures and water stress pepper (Capsicum annum L.) plants were
utilized at a population of 14 plants m2, light intensity ranged from 3000-5500
footcandles and a 44 mm layer of water were applied to fruiting stage. External and
internal temperatures, light intensity, water vapor pressure deficit, nutrient solution,
substrate and leaf temperatures were recorded by using a IR thermometer. Results
indicated a high buffer capacity regarding environmental variables. For example, -5 oC
external temperatures, without gas heating, resulted in 14, 12, 12, and 8 oC for leaf,
substrate, nutrient solution, and internal tunnel, respectively. Combination of internal
temperatures of 40 oC and one KPa water potential for substrate resulted in a substrate
temperature from 22 to 26 oC, while leaf temperature ranged from 25 to 28 oC. It is
concluded that the system is economical, productive and efficient in conservation and
use of energy and water.
18
Water Requirements and Yield of Peach Trees Irrigated by Microsprinkler
and Subsurface Drip
David R. Bryla
USDA ARS
Horticultural Crops Research Laboratory
3420 NW Orchard Avenue
Corvallis, OR 97330
Email: [email protected]
Abstract
The seasonal water requirements and yield of 5-year-old ‘Crimson Lady’ peach
trees (Prunus persica (L.) Batsch) irrigated by microsprinkler and subsurface drip were
compared in central California. Early in the season, trees irrigated by microsprinkler
required nearly twice as much water to maintain the same water status, measured as
midday stem water potential, as trees irrigated by subsurface drip. However, as the
canopy developed, relatively less and less water was required by microsprinkler. By the
time the canopy was fully developed, and the soil surface beneath the trees was nearly
100% shaded at midday, trees irrigated by microsprinkler and subsurface drip
required the same amount of water to maintain equal water status. Summer pruning
reduced the water requirements in both treatments, but once again increased the
relative amount of water required by microsprinkler. By the end of the season, trees
irrigated by subsurface drip used 26% less water than trees irrigated by
microsprinkler. Subsurface drip irrigation also increased fruit size by 8% and
marketable yield by 29% over microsprinkler irrigation, and consequently increased
water use efficiency in peach by 74%.
19
Effect of Early Irrigation Cut-off on Quality and Yield of Processing
Tomatoes
M.D. Cahn
University of California, Cooperative
Extension, Monterey Co.
1432 Abbott St. Salinas, CA 93901
USA
E.V. Herrero
University of California, Cooperative
Extension, Sutter/Yuba Counties
142A Garden Hwy, Yuba City CA 95991
USA
B. R. Hanson
Dept. of Land Air and Water Resources,
University of California
Davis CA 95616
USA
T. K. Hartz
Vegetable Crops Dept.
University of California
Davis CA 95616
USA
E. M. Miyao
University of California, Cooperative
Extension, Yolo/Solano Counties
70 Cottonwood St.
Woodland, CA 95695
USA
Abstract
Water management was monitored in 16 commercial processing tomato fields to
evaluate strategies for improving fruit quality during the 2001 and 2002 seasons. Fields
were selected to represent a range of soil types, irrigation systems (drip, furrow, and
sprinkler), and water table depths in Sutter and Yolo Counties, CA. Soil textures of
fields ranged from clay to sandy clay loam and water table depths ranged from 60 cm to
> 120 cm below the soil surface. Irrigation trials were conducted to evaluate the effects
of early irrigation cut-off on fruit quality at each field site. All trials included a grower
(late cut-off) and an early cut-off treatment. Soil moisture was monitored in each plot
to a 110-cm depth using a neutron probe. Fruit yield and quality were evaluated from
hand-harvested plots. Early irrigation cut-off was found to increase soluble solids of
fruits when treatments were sufficiently severe to reduce soil moisture in the upper 60
cm of the soil profile during fruit ripening. Marketable fruit yield was reduced in all
fields where early cut-off increased soluble solids. Decreased fruit weight was measured
in the early cut-off treatments at field sites where fruit had increased brix levels. Results
were consistent in crops grown under sprinkler, furrow, and drip irrigation and a range
of soil textures.
20
Irrigas – a novel system for irrigation control
A.G. Calbo and W.L.C. Silva
National Vegetable Crop Research Center – Embrapa Vegetables
Caixa Postal 218, CEP 70359-970 Brasilia, DF, Brazil
E-mail: [email protected]
Abstract
Irrigas - a novel system for irrigation control, patented by Embrapa, is made out
of a porous cup, connected by a flexible plastic tube to a small transparent cuvet. The
measurement is based on the air passage obstruction, while the soil water tension
remains smaller than a critical value. When the water tension becomes higher than this
critical value, air permeates the cup indicating the time for the irrigation. Air
permeation measurement can be made by immerging the transparent cuvet into a water
recipient. Differently from tensiometers Irrigas porous cup cavity and the tube are kept
full of air, instead of water. This is the differential and advantageous factor, that
eliminates usual tensiometer difficulties caused by the need of porous cup water
saturation and the entrance of air in the system. Besides being cheaper and easier to
use, Irrigas is as quick and reliable as the best tensiometers available in the market.
Defining critical capillary rise properties for growing media used with
subirrigation devices in nurseries
Caron, J., Elrick, D.E., Beeson, Jr., R.C. and J.Boudreau.
Abstract
Efficient use of irrigation water is becoming a major issue in nursery production.
This is a result of increasing risks of shortages during drought periods and limited
water supplies in general, both of which can lead to restrictions on irrigation. Over the
years, different systems to conserve water have been proposed for overhead irrigation
in nurseries. Reclaimed or tertiary water, catchment basins, ebb and flow, capillary mat
and microirrigation, among other systems, appear to be sound procedures for saving
water. For some irrigation systems (ebb and flow and capillary mat), good substrate
capillary properties are needed, although standards for such properties are lacking.
This study compared substrates made of mixtures of peat, bark and sand, which
resulted in contrasting capillary properties in a nursery experiment, to setup guideline
values for proper operation on capillary mat devices. It also proposes a theoretical
model using the hydraulic characteristics of a growing media to predict its suitability
for proper operation. Substrates with 60% (per volume) sphagnum peat were found to
provide the best capillary rise and the best growth, based on observations and on the
theoretical model, relative to substrates with 30% sphagnum or 30% sedge peat. The
pronounced hysteretic phenomenon of coarse substrates was an important factor in
reducing their capillary performances.
21
Progress in the Development of Partial Rootzone Drying of Apple Trees
Horst W. Caspari* and Todd Einhorn
Department of Horticulture and Landscape
Architecture, Colorado State University,
Grand Junction, CO 81503, USA
[email protected]
Preston K. Andrews
Washington State University, Department of
Horticulture and Landscape Architecture,
Washington State University, Pullman, WA
99164
Thomas Auvil5 and James R. McFerson
Washington Tree Fruit Research
Commission, 1719 Springwater Avenue,
Wenatchee, WA 98801, USA
Brian G. Leib
Washington State University, Irrigated
Agriculture Research & Extension Center,
24106 North Bunn Road, Prosser, WA
99350, USA
Leonardo Lombardini
Washington State University, Tree Fruit
Research and Extension Center, 1100 N
Western Avenue, Wenatchee, WA 98801,
USA
Abstract
Since 1995, we have evaluated Partial Rootzone Drying (PRD) on apples. Initial
experiments were conducted with apple varieties ‘Gala’, ‘Fuji’ and ‘Braeburn’ in the
temperate climate of New Zealand. In 2001, we started four multi-year studies with
varieties ‘Gala’ and ‘Fuji’ in the semi-arid climates of Colorado and Washington State.
Irrigation systems included microsprinklers, surface and sub-surface drip lines. At each
site, the PRD regime was compared to a well-watered Control and a season-long deficit
regime (DI). Both, PRD and DI were irrigated at 50 % of the Control’s volume. In
contrast to PRD where only half the rootzone was watered the DI and Control
treatments were irrigated over the full rootzone. At the Colorado sites, two further PRD
treatments received 25 % or 75 % of the Control’s volume on 25 % or 75 % of the
surface area (PRD25 and PRD75, respectively).
This paper presents the main results achieved with PRD from four sites over two
years. Seasonal potential evapotranspiration exceeded 1000 mm and precipitation was
less than 160 mm in both years at all sites. Seasonal irrigation inputs ranged from a low
of 120 mm for PRD25 with drip irrigated ‘Gala’ to a high of 765 mm for the Control
with microsprinklers on ‘Fuji’. There were no significant treatment effects on ‘Gala’
yield, fruit size and fruit quality at harvest and after cold storage in either year. With
‘Fuji’, no significant effects on yield and fruit quality were found in the first year, but
mean fruit size was reduced by PRD compared to Control at one site. In the second
season, the DI treatment tended to reduce fruit size at both sites, and yield was
significantly lower at one site. At one site, PRD and DI fruit were firmer and had higher
concentration of soluble solids at harvest and after being kept at room temperature for
seven days. Fruit disorders (sunburn, russet, watercore) have not been affected by
treatments. Our results indicate that PRD and DI allow large water savings with minor
or no impacts on fruit size and yield while potentially improving fruit quality. Seasonal
crop coefficients for apple might be reduced to 0.3 or less with new or modified
irrigation techniques.
22
Irrigation of Shiraz Winegrapes Using Partial Root-zone Drying
Y.M. Chalmers, M.P. Krstic and G. Kelly
Department of Primary Industries
P.O. Box 905
Mildura, Victoria, 3502
Australia
Abstract
Partial root-zone drying (PRD) is an irrigation management technique that has
the potential to improve water use efficiency whilst enhancing fruit quality
characteristics of wine grapes. A field trial was established in North-West Victoria,
Australia to determine whether Vitis vinifera L. var. Shiraz grown in semi-arid
conditions, are actually producing a true PRD response when exposed to this type of
deficit irrigation. Treatments consisted of a control irrigated to estimated crop
evapotranspiration by two drip lines on either side of the vine row (100% Control), a
deficit treatment irrigated by a single drip line (50% Control), and two PRD treatments
alternated between single drip lines on each side of the vine row on a 2 irrigation (50%
PRD2) and 14 day (50% PRD14) cycle. Stomatal conductance (gs), leaf water potential
(Ψl) and total vine leaf area (LA) were measured at regular intervals during the growing
season. Overall, there were no significant changes in Ψl between any treatment for
measures at 1000 h and 1500 h. However, gs was significantly reduced at 1500 h for the
50% Control and both PRD treatments compared with the 100% Control. Although a
reduced gs was observed in both PRD treatments compared to the 100% control, the
50% control also responded similarly even though irrigations had only been applied to
one side of the root zone for the entire season. LA remained unaffected despite some
treatments receiving half the amount of water. Despite an improvement in the ratio of
yield to irrigation applied (WUE) as a result of PRD, there is still much to learn in
respect to commercial application of this technique.
23
Management of Irrigation through Conjuctive Use of Water for
Acquaculture and Horticulture: an Indian Overview
Chaudhari L. P.
N-1/8 Narayan Pujari nagar , A. G Khan road , Worli, Bombay, 400018,
INDIA .
Abstract
Aqua farming has emerged as one of the more promising industries in the world
with considerable growth potential expected to contribute around the quarter of global
fishery the year 2000 AD. The aqua farming has a multidimensional in perspective
agricultural growth. It is a tool for utilizing land and water more economically and
optimally for increasing the productivity of both natural resources, land and water
through sustainable agriculture. The countries in the Asia-Pacific region have vast and
varied aqua farming resources. Oftenly these are these are main source of Irrigation in
this region. The overuse of water causes salinity problem in many countries reducing
the cultivating area resulting reduction in agriculture reduction. An attempt has been
made in this paper to develop the plan for irrigation water management for the
aquaculture and horticulture from Indian experience. The paper also evaluates the
water quality criteria for increasing the agricultural productivity. The methodology is
based on the economics of the conjunctive use of irrigation water for horticulture and
aquaculture and also for agriculture. The main aim is to utilize the saline land for aqua
farming and to reduce the soil salinity in irrigated land to increase the productivity of
the land and the water.
Series of the observations were taken on the various aspects of irrigation and soil
salinity management for aqua farming using different methods to maintain the quality
of land and the water. Also the relative economics of aqua farming and horticulture
system under alternative water conserving irrigation management options, has been
compared with the resources available.
The result obtain demonstrate the implication of increase in yield in horticulture
including agriculture and indicate the necessity of optimal and suitable use of natural
resources for increasing the agricultural productivity. The result signify that the soil
salinity can be managed using water management practices and the additional area can
be brought down under agriculture. The result obtained also suggest that significant
economic gains can be had from adopting conjunctive use of water to maintain the
quality criteria for increased production in horticulture and agriculture. Apart from
result of water, it also signifies that the increase in the production can be achieved
through reuse of water reducing the soil salinity problems in command area.
24
Production of Quality Aroid Foliage Plants Using Collected Stormwater
and Irrigation Runoff as a Irrigation Source
Jianjun Chen and Richard C. Beeson, Jr.
University of Florida, IFAS, Mid-Florida Research and Education Center
2725 Binion Road, Apopka, FL 32703
Abstract
Containment and reuse of stormwater and irrigation runoff is considered an
effective measure to conserve water and reduce nutrient runoff in nursery crop
production. Collected water has been used as an irrigation source for producing
landscape ornamentals but has rarely been used for greenhouse containerized crops in
the US. This study evaluated whether quality aroid foliage plants could be produced
using collected stormwater and irrigation runoff as an irrigation source. A collection
basin captured irrigation runoff from a landscape plant production bed and
stormwater from greenhouse roofs. One cultivar each of Anthurium, Aglaonema,
Dieffenbachia, Epipremnum, Philodendron, Spathiphyllum, and Syngonium was
planted in 15-cm containers filled with Vergo Container Mix A. Potted plants were
grown on ebb-and-flow trays fertigated with a nutrient solution made from a watersoluble fertilizer dissolved in either the collected water or well water. Plant canopy
heights, widths, number of leaves, flower accounts and quality (if any), and leaf areas of
the largest leaves were recorded at the beginning and the end of production. Plant
overall quality was graded at the end of production. No growth disorders or diseases
related to water sources were observed. Plant overall quality when fertigated with the
collected water was either higher than or equal to that of the control plants. This study
indicated that collected stormwater and irrigation runoff can be an alternative source
for producing quality aroid foliage plants in greenhouse conditions.
25
Influence of Irrigation on Cropping of ‘Elstar’, ‘Golden Delicious’,
‘Idared’ and ‘Jonagold’ Apple Trees
Z. Cmelik1
Faculty of Agriculture
University of Zagreb
10000 Zagreb, Croatia
Tojnko
Faculty of Agriculture
University of Maribor
2000 Maribor, Slovenia
Keywords: Malus x domestica, dynamic of yield, cumulative yield, alternate bearing
Abstract
Four apple cultivars grafted on M.9 rootstock were grown at high density
(‘Elstar’ and 'Jonagold' 2500 trees/ha, ‘Idared’ and 'Golden Delicious' 3000 trees/ha).
The trial was designed as split-block comprising two treatments (irrigation without
fertilisers, and control - without irrigation and without fertilisers) and two timing
variants of irrigation (from 1 May - 20 June – variant A, and from 1 May to 1 August –
variant B). The treatments were imposed beginning in the second year after planting
and lasted eight years (1992-1999). It was found that the intensity of effects of irrigation
on cropping of individual cultivars varied. To a certain extent 'Elstar' and 'Golden
Delicious' responded similarly to treatments, and achieved the best results when were
irrigated from 1 May to 20 June. Cumulative yield of ‘Idared’ was not affected by
irrigation, however, irrigation decreased percentage of bienniality. Similarly, irrigation
had no consistent influence on cumulative yield of ‘Jonagold’, but increased degree of
alternate bearing.
Does Rootstock Dwarfing Correlate with Hydraulic Conductance and/or
Xylem Dysfunction?
Shabtai Cohen1
Institute of Soil, Water and Env. Sciences,
A.R.O., P.O.B. 6, Bet Dagan 50250
Israel
Email: [email protected]
John Bennink2 and Mel Tyree2
Northeastern Research Station
USDA Forest Service
705 Spear St., S.
Burlington, VT, 05403, USA
Abstract
Hydraulic conductance of a series of unworked apple rootstocks were measured
in intact plants, and in cut root systems. Significant differences were found between the
rootstocks, but there was no general correlation between conductance and dwarfing
potential. Staining the xylem with basic fuchsin showed different patterns of water
transport in the stem. Flushing with water followed by staining indicated that much of
the xylem does not transport water in normal conditions, i.e. it is dysfunctional. There
was some indication that dwarfing rootstocks have more extensive xylem dysfunction
than vigorous rootstocks. The implications with regards to dwarfing will be discussed.
26
Less Water Makes More Money on Loquat
J. Cuevas and J. López-Plaza
Dpto de Producción Vegetal
Universidad de Almería
04120 Almería, Spain
J. Hueso
E.E de Cajamar ‘Las Palmerillas’
Autovía del Mediterráneo km 419
04710, El Ejido, Almería, Spain
Abstract
Loquat is a subtropical fruit crop increasingly planted in Mediterranean
climates. Such areas often suffer from drought episodes leading to water shortages.
With the aim to reduce water consumption on loquat we have initiated a suitable
regulated deficit irrigation (RDI) strategy that not only saves water but also increases
revenue. Both aspects have been conciliated previously by postharvest RDI from midMay until August. To optimize water management we pretend now to define more
precisely the best dates for RDI. Three treatments, incorporating a reduction of 66%
water needs either on June, July or August, and controls, receiving full water needs,
were implemented on ‘Algerie’ trees growing at Almería (SE Spain). Stress applied on
July resulted the most promising, advancing bloom period 13 days. As a consequence of
such advancement, harvest is programmed earlier increasing harvest value. Water
reduction on June left blooming date unaffected whereas stress on August delayed full
bloom by 8 days, suggesting that on August flower development is on course, and
detrimental effects are caused. Our results permit to enlighten characteristics that
define loquat as a model for successful RDI: responsiveness to water deficit in term of
advance blooming, earliness as a key parameter defining crop value, and total
separation of vegetative and reproductive phases that makes easier the implementation
of RDI strategies during non-critical periods. Soil, climate, and watering system are also
requirements of major impacts in the success of such strategies. Sandy soil, scarce
rainfall, mainly during winter, and drip irrigation allowed a quick implementation of
water deficit without unwished disturbance due to rain, and a fast alleviation of the
stress. Precise management to avoid a negative impact on fruit quality and similitude
with other subtropical fruit trees will be discussed in order to facilitate a more ample
adoption of RDI strategies in the Mediterranean.
27
Measuring water potential in mango trees
M.A.C. Damaske and E.W. Pavel
Dept. of Plant Production & Soil Science
University of Pretoria,
Pretoria 0002
South Africa
Abstract
Using water potential as water status indicator is not commonly used in mango
trees because the mango is a latex type sap conducting plant. When measuring water
potential in mango using a pressure bomb, it is often not easy to distinguish between
latex exudation and water outflow. Stem and leaf water potential and stomatal
conductance were measured in six-year-old ‘Kent’ mango (Mangifera indica L.) trees in
the field to characterize daily and seasonal patterns of those parameters. Potential and
sensitivity of water potential measurements were tested by studying mango tree
responses to drying cycles. Our results indicate that it is possible to measure water
potential in mango trees by using a pressure bomb and that reliable water potential
data can be obtained.
28
Advanced weighing equipment for water, crop growth and climate control
management
R. de Graaf, Applied Plant Research
P.O. Box 8
2670 AA Naaldwijk l
The Netherlands
E-mail, [email protected]
Abstract
Crop transpiration is, after photosynthesis, the most important plant process. A
number of years the Applied Plant Research station Naaldwijk has used crop
transpiration measurements with ever more advanced weighing equipment. Ultimately
a basis weighable gutter system has developed that gives satisfaction under practical
circumstances and seems to offer interesting application possibilities.
A weighable gutter system is an instrument for measuring the crop
transpiration. With this the water supply can be automated and insight arises about the
pattern of crop transpiration over short and long periods. With weighable gutters it is
also very possible to measure and to check the amount of the water supply and the
water content of the substrate. Separate of the weighable gutters the amount of
drainage water can be measured continuously.
In combination with the measuring of the gutters and the amount of drainage
water the pattern of the fresh plant weight is measured on a separate beam which the
plants are suspended. Weighing of the plant growth and crop transpiration give very
useful information about plant activity. By a too fast rising of the crop transpiration
the water uptake stays behind, with as consequence that more water disappears out the
plant than is taken up by the plant. In such situations there appears a shrinking of the
plant which can be so big on a certain moment that recovery does not take place and
finally causing stress of the plant. Crop weighing gives the opportunity to detect stress
in an early stage, after which certain measures can be taken to prevent or to minimize
stress.
A “simple” weighable gutter system for example for cucumber consists of a
gutter of 4 – 6 meter length, a crop beam and a drainage collecting container. From all
parts of the system the weight is measured on line. For measuring the weight so called
power transducers are used. Via the computer the signal is converted to a certain
weight.
The weighable gutter and the crop beam hang on two power transducers, the
drainage collecting container stands on a power transducer.
On the computer screen there are reproduced as well as actual data but also data
over short and long periods. The recorded data can be used for taking decisions and
management the water supply, climate control and crop control. Especially these
aspects are the extra value of a weighable gutter system.
29
Modeling Bare Soil Evaporation
J. Paulo de Melo-Abreu
ISA, Tapada da Ajuda
1300 Lisboa,
Portugal
Richard L. Snyder
LAWR, University of California
Davis, CA 95616
USA
Terry A. Howell
USDA Research Unit
Bushland, TX 79012
USA
Abstract
Most bare soil evaporation models follow a two-stage process. Stage 1
evaporation rate (Es) is maximum (Ex), and is usually estimated as a constant fraction
(Kx) of the reference evapotranspiration (i.e., Ex = KxETo). During Stage 2, evaporation
rate is related to the square root of time after wetting. The model presented in this
study, simulates Stage 1 evaporation directly by the Penman-Monteith equation. The
aerodynamic resistance of the soil boundary layer is calculated with a zero displacement
value equal to zero and a roughness length of 0.001 m. During Stage 2, the cumulative
actual evaporation is directly proportional to the square root of the cumulative Ex,
instead of time. The proportionality factor is a soil hydraulic factor (β). The model was
calibrated and validated using data sets from California, Arizona and Texas. In the first
two locations the soil was initially wetted and allowed to dry for several days without
rewetting, and hourly soil evaporation rate was determined as the residual of the energy
balance. In Texas, daily soil evaporation was measured by lysimetry. In this case, there
was initial wetting and rain rewetted the soil sometimes. The β soil parameter, which is
soil specific, was between 2.6 and 4.7 mm0.5. The slopes of the regression through the
origin of estimated versus measured accumulated daily values of soil evaporation,
immediately after first wetting, were between 0.91 and 1.03, and R2 was between 0.96
and 1.00. Kx varies with ETo, and with location (in this study, local averages were
between 0.8 and 0.9). Therefore, the present model may have the advantage of
calculating directly ETx. Moreover, it may easily be extended to simulate also the soil
evaporation during crop growth, if the reduction of radiation and attenuation of the
wind speed are accounted for.
30
Effect of soil cover and irrigation on the growth and fertility of the
blackcurrant variety Dyana
FERENC DENES
Research and Development Institute for Fruit Production
Fertod
Keywords: irrigation, soil cover, blackcurrant, fertility
Abstract
An experiment was set up on three blackcurrant varieties (Aranka, Dyana and
Otelo) and one redcurrant variety (Jonkheer van Tets) to study the effect of irrigation
and soil cover. Due to technical problems with the irrigation, the four treatments could
only be set up in one replication, but the large number of plants (134 plants/plot)
allowed the data to be statistically evaluated. In the first year the growth of the
varieties was measured, and the treatment-dependent susceptibility to powdery mildew
and the degree of aphidinfection were scored. In the second year no studies on the effect
of the treatments on fruit yield were planned, but the large quantity of flowers
produced by the variety Dyana suggested that it was worth making observations on
fertility.
From data recorded in 2001 it was concluded that irrigation and soil cover had a
favourable effect on the total growth and mean shoot length of Dyana. This effect could
be regarded as additive, as could the effect on the length of the internodes. By contrast,
soil cover reduced the ratio of flowerbuds within the total number of buds on each bush,
and the number of clusters formed in each bud. However, soil cover increased the
number of flowers per cluster. An investigation of the site of flower formation indicated
that as the result of irrigation a considerable number of flowers were formed on
secondary branches, which were often very short. Among the data recorded on the
quantity of fruit harvested, special mention should be made of the fact that on plots
covered with black polythene seed setting was 10 % higher than on corresponding plots
without soil cover. The same effect of soil cover was observed with respect to the cluster
length and mean cluster weight. The effect of irrigation and soil cover treatments on
the yield was additive. The role of irrigation was decisive for the quantity of fruit per
bush, but covering the soil with black polythene also had a significant positive effect on
the yield.
31
Scaling up Water Use Efficiency from Leaf to Whole Plant in Table Grape
trained to Tendone System
L. de Palma
Dept. Scienze Agro-Ambientali, Chimica e
Difesa Vegetale, University of Foggia, Italy
V. Novello
Dept. Colture Arboree,University of Torino
Grugliasco TO, Italy
G. Mattii and M. Pancrazi
Dept. Ortoflorofrutticoltura, University of
Firenze, Sesto S.G. FI, Italy
Abstract
Among the main topics of physiological plant ecology, leaf gas exchanges occupy a
prominent position since most part of the plant dry matter derives from leaf net CO2
assimilation (A), almost all the plant water uptake is utilized for leaf transpiration (E) and
the A:E ratio, that is, the photosynthetic leaf water use efficiency (WUE), is a fundamental
factor affecting the crop productivity especially in water limited environments, such as in
South Italy. A research project of national interest has been carried out in Italy aiming at
the ecophysiological characterization of typical viticultural systems of great economical
importance. Many studies on leaf gas exchanges of cultivated crops focus on the individual
leaf functioning, which is relatively simple to be measured and may be considered as an
indicator of the plant response to the ambient conditions. However, in order to get a more
reliable interpretation of results, several other factors should be taken into account, e.g.
total leaf area, canopy architecture, intra-canopy spatial variability and leaf demography,
which are commonly missed by leaf measurements. Whole plant measurements of CO2 and
H2O vapor exchange give a more global indication of the plant functioning, as well as
measurements of energy and matter exchanged by vegetation in large field plots give a
comprehensive indication of environmental effects on plant growth. However, this types of
measurements are more complex to be performed and may overlook details of relevant
importance for the improving of canopy management. Scaling up gas exchange from leaf to
whole canopy is an important objective of ecophysiological studies but difficult to realize
because of the complexity of the leaf arrangement and their light exposure within the
canopy. Although detailed modeling of leaf area development and light penetration can
integrate these factors, validation is needed to estimate photosynthesis and transpiration at
canopy level. One of the aim of our research project was to concentrate, in the time and in
the space, the operating ability of several Research Units and integrate different scales of
surveying, that is, leaf, whole plant and entire vineyard, in order to get a more complete
information on the functioning of a typical viticultural system. Within this objective,
photosynthetic leaf water use efficiency has been evaluated in field-grown table grape
trained to horizontal trellis system (tendone) in South Italy, either on undisturbed
individual leaves of different canopy layers or on whole vines. Individual leaf gas exchange
was measured by means of a portable gas analyzer, and whole canopy gas exchange was
measured by means of a transparent polyethylene ‘balloon’ chamber. The diurnal patterns
assessed with the two type of measurements have been plotted and the results have been
compared and discussed.
32
Leaf Water Use Efficiency in Tendone trained Canopy: a Contribute to the
Ecophysiological Characterization of a Table Grape Growing System
L. de Palma
Dept. Scienze Agro-Ambientali, Chimica e
Difesa Vegetale, University of Foggia, Italy
V. Novello
Dept. Colture Arboree,University of Torino
Grugliasco TO, Italy
Abstract
One of the principal factors affecting plant physiology and productivity is the
canopy architecture, which is known to influence the xylem transport, the microclimate
at leaf level and, as a consequence, the rate of leaf photosynthesis and transpiration,
that is, the photosynthetic leaf water use efficiency (WUE). In water limited
environments, particular importance is attributed to this parameter. A research project
aiming at the ecophysiological characterization of typical viticultural systems has been
carried out in Italy. In South Italy, the table grape vineyard trained to ‘tendone’ trellis
is a typical cropping system consisting of a large horizontal canopy, and is extended
over 33,000 ha. Due to its structure, this system is able to induce a heavy yield and a
fresh and ventilated canopy microclimate which is beneficial for the ripening bunches.
The natural number of canopy leaf layers varies with the vine vegetative vigor and
exalts differences in the contribute given by leaves having different spatial position, and
different age, to the leaf gas exchange of the foliage. The presence of multiple leaf layers
causes a mutual leaf shading which is known to depress the photosynthetic rate much
more than the transpiration rate, dramatically reducing WUE. However, due to the
vertical position of the young lateral shoots, having small leaves, and due to the canopy
‘gaps’, leaves are exposed to a wide range of photon flux intensities; hence, a large
variation occurs in the amount of water vapor dissipated per amount of fixed carbon
dioxide, which is known to represent most part of the plant dry matter. In order to
contribute to the ecophysiological characterization of the tendone canopy, in the present
work we assessed, on undisturbed leaves located at the different leaf layers, the diurnal
pattern of photosynthetic photon flux, leaf net carbon dioxide uptake and transpiration
rates per leaf area unit, with the aim to study the real distribution of the photosynthetic
leaf water use efficiency within this type of foliage.
33
High yields of mechanically harvested snap beans as induced by moderate
water stress during flowering
P. Deproost*, F. Elsen and M. Geypens
Soil Service of Belgium, Willem de Croylaan 48, B-3001 Heverlee, BELGIUM.
*Corresponding author. E-mail address: [email protected]
Abstract
Irrigation guidelines obtained from laboratory experiments and open field trials
in subtropical conditions fail when applied for snap bean (Phaseolus vulgaris L.)
cultivation under temperate climate conditions and in mechanised farming systems.
Homogeneous pod development and ripening is essential in producing high yields of
snap beans, especially when mechanisation implies that the harvest time is limited to
one specific day, determined by the processing industry. During the period 1997-2000,
14 experimental fields served to determine an appropriate irrigation scheduling
strategy for the cultivation of snap beans on loam and sandy loam soils under temperate
climate conditions. The treatments consisted of irrigation application at different soil
matric potentials (-30 kPa, -50 kPa, -80 kPa and -200 kPa) in the upper 30 cm soil layer,
which were either maintained during the entire growth period or related with specific
growth stages (vegetative development, flowering and pod ripening). The irrigation
control was based on a water balance method, regularly checked by gravimetric water
content and TDR measurements. Although high irrigation frequencies generally
favoured strong vegetative development and stimulated the generation of pods,
moderate drought stress during flowering induced yield rises of 30 to 70% when
compared to frequently irrigated snap beans. A detailed analysis of pod development
and ripening indicated that the higher yields were related to a shorter flowering stage, a
more homogeneous pod development and an advanced ripening of the pods. During
flowering the application of one irrigation dose ahead of time – i.e. before the
appropriate soil matric potential level was reached - did not only mean a waste of
labour, money and maintenance costs, but resulted in a yield reduction of green beans
which averaged 2.3 tonnes/ha.
34
Regulated Deficit Irrigation in Peach Tree in Semi-arid Climate
B. Dichio,C. Xiloyannis, V. Nuzzo, G. Montanaro and A.M. Palese.
1Dipartimento di Produzione Vegetale, Università della Basilicata, contr. Macchia Romana,
85100 Potenza, Italy.
Abstract
The aim of this paper was to identify how to minimise irrigation water use by
applying regulated deficit irrigation (RDI) during phenological stages least sensitive to
water deficit.
The effect of two different levels of RDI were studied in a peach orchard (cv
Springcrest). From bud break to harvest, irrigation was managed by applying 100% of
ETc, while from harvest to early autumn, irrigation was equivalent to 100%, 50% and
25% of ETc. Plant water status was monitored measuring the predawn leaf water
Potential, (Ψwpd) and the stem water potential (Ψwstem) while soil water content was
determined by means of the gravimetrical method. For each treatment the water use
efficiency (WUE) was measured throughout the season using the leaf gas exchange
analysis. During a 3-year trial, no significant reductions in yield or quality were found
for the 50% ETc treatment, whereas about 1,000, 1,800 and 2,400 m3ha-1 of water
where saved in the first, second and third years. The 25% treatment did reduce quality
and yield significantly. Where water is in short supply there is a clear benefit to be
obtained through the use of 50% RDI during the postharvest period - especially for
early-harvest peaches.
35
Regulated Deficit Irrigation in Peach Tree in Semi-arid Climate
B. Dichio,C. Xiloyannis, V. Nuzzo, G. Montanaro and A.M. Palese.
1Dipartimento di Produzione Vegetale, Università della Basilicata, contr. Macchia Romana,
85100 Potenza, Italy.
Abstract
The aim of this paper was to identify how to minimise irrigation water use by
applying regulated deficit irrigation (RDI) during phenological stages least sensitive to
water deficit.
The effect of two different levels of RDI were studied in a peach orchard (cv
Springcrest). From bud break to harvest, irrigation was managed by applying 100% of
ETc, while from harvest to early autumn, irrigation was equivalent to 100%, 50% and
25% of ETc. Plant water status was monitored measuring the predawn leaf water
Potential, (Ψwpd) and the stem water potential (Ψwstem) while soil water content was
determined by means of the gravimetrical method. For each treatment the water use
efficiency (WUE) was measured throughout the season using the leaf gas exchange
analysis. During a 3-year trial, no significant reductions in yield or quality were found
for the 50% ETc treatment, whereas about 1,000, 1,800 and 2,400 m3ha-1 of water
where saved in the first, second and third years. The 25% treatment did reduce quality
and yield significantly. Where water is in short supply there is a clear benefit to be
obtained through the use of 50% RDI during the postharvest period - especially for
early-harvest peaches.
Researches regarding the correlations from the soil-water-plant system in
autumn cabbage crop in the conditions of the moderate wet area from
Western Romania
Domuþa C, Ciobanu Gh, Sabãu NC,
Bandici Gh, ªandor Maria
Abstract
The paper presents the results of the researches carried out during 1990-2002 in
Oradea, Western Plain of
Romania. Inverse links, statistically assured, were
quantified between number of days with soil water reserve bellow easily available water
content (on irrigation depth ,0-50 cm) and yield, respectively water use efficiency ; a
direct link, statistically assured too, was registered between this parameter and yield
gain obtained using the irrigation. The microclimate conditions were quantified by
climate index(de Martonne aridity index,Palfai aridity index, Domuta climate index)
and between these indexes and yield a direct links were quantified. There is a direct link
too, between the cabbage water consumption and yield obtained.
The correlations quantified in the soil water-plant system are the arguments for
the irrigation opportunity in autumn cabbage crop from moderate wet area of Western
Romania.
36
Water Use of an Apple Orchard in a Cool Humid Climate: Measurement
and Modeling
D. Dragoni, A.N. Lakso, and R.M. Piccioni
Fruit Crop Physiology Program
Cornell University
Horticultural Sciences Department.
NYS Agric. Experiment Station
Geneva, NY 14456 -USA
Abstract
For irrigation design and scheduling, water use of crops is commonly estimated
from grass reference evapotranspiration (ETo) multiplied by published crop
coefficients (kc). This method is assumed to adjust crop values in different climates.
However, the simple application of kc may not be accurate in cool, humid climate,
especially for tall crops well coupled to bulk air. The aim of this work was to measure
actual water use in an apple orchard in New York, and to test the vaules against
published kc values. Measurements of water use in dwarf apple trees were made with
heat pulse sap flow gauges calibrated with whole-tree gas exchange chambers (to check
or correct potentials errors related to the velocity-to-flow assumptions). Since the
calibration of the gauges may drift with time, calibrations were done at two different
one-week periods during the season. Daily ETo was estimated from meteorological data
acquired nearby. Results suggest the inadequacy of using kc values directly from arid
climates in cool and humid climates since published kc values generally overestimated
the measured water use rates. Also, the crop coefficient concept implies that grass and
orchards behave the same in all climates; this does not seem to be true in cool humid
climates. Grass-to-tree differences in advective flows, boundary layer conditions and
stomatal regulation appear to result in varying ET ratios. Modifications that take into
account the specific characteristics of apple tree canopy (like light interception), and
stomata regulation by environmental factors have been considered to adapt a general
formulation of Penman-Montieth equation to the orchard case. Results are in good
agreement with field measures, although overestimations can arise during periods when
internal plant factors or other stresses may reduce stomata conductance.
37
Statistical Control Charts for Quality Control of Weather Data for
Reference Evapotranspiration Estimation
S.O. Eching
Office of Water Use Efficiency
California Dept. of Water Resources
P.O. Box 942836
Sacramento, CA 94236-001
USA
R.L. Snyder
Dept. of Land Air and Water Res.
University of California, Davis
Davis, CA 95616
USA
Keywords: Time variant control chart, evapotranspiration, CIMIS, quality control, mean,
standard deviation, control limit
Abstract
Data quality control is a necessary component of any weather station network
used for estimating reference evapotranspiration (ETo). The absence of a quality
control program can result in poor quality ETo data that severely limits its usefulness
for irrigation scheduling. Statistical quality control criteria are developed for assessing
quality and reasonableness of hourly and daily weather data for the California
Irrigation Management Information System (CIMIS) weather stations. The quality
control criteria, based on means and standard deviations, are developed from historical
CIMIS weather stations data. Two statistical quality control limits, 3-sigma and 2-sigma
upper control limit and lower control limit, are developed. The two control limits are
integrated into existing data screening rules forming new CIMIS data quality control
criteria. A new version of a control chart, Time Variant control chart, is introduced.
Statistical control charts have been widely used in the manufacturing industry for
process mean or variability monitoring and quality control. Control limits developed
herein are similar to those used in the manufacture of products. However, unlike in
manufacturing where one seeks to attain a state of statistical control, these control
limits are used to identify data that fall outside the control limits. Such data is then
flagged with a quality control flag.
38
Estimating Missing Reference Evapotranspiration by Spatial Correlation
Analysis
S.O. Eching
Office of Water Use Efficiency
California Department of Water Resources
P.O. Box 942836
Sacramento, CA 94236
Keywords: Irrigation scheduling, normalized difference, regression equation, CIMIS.
Abstract
Irrigation scheduling based on reference evapotranspiration (ETo) data depends
on continual availability of ETo data. For high frequency irrigation, daily ETo data are
inevitable. When current ETo data cannot be estimated or it is of questionable quality,
it must be estimated. Often historical data is used as an estimate. This study presents a
technique, based on spatial correlation, for estimating missing data. Long term average
daily ETo for each month of the year from 10 California Irrigation Management
Information System (CIMIS) stations were correlated with each other using multiple
correlation. Of the 540 possible average ETo pairs representing 55 station pairs, only
22 pairs had at least one month with correlation coefficients less than 0.975. Some of
these poorly correlated stations were located relatively close to each other. It is
speculated that the poor correlation is due to urban heat island effect. The mean and
standard deviation of normalized relative difference in daily ETo for station pairs with
multiple correlation coefficient greater than 0.975 were calculated. Regression
equations, the end product of the estimation technique, were developed for 27 station
pairs with standard deviation of normalized difference less than 0.1. The ability of the
regression equations to predict missing data was tested by comparing the 2001 daily
ETo values (current ETo) for selected stations with ETo predicted by regression. Also,
current ETo values for the same stations were compared with the station historical
data. The regression equations predicted values closer to current ETo values compared
to historical data indicating that the regression equations would be better for estimating
missing data than historical data.
39
Partial Rootzone Drying and Deficit Irrigation of ‘Gala’ Apples in a Semiarid Climate
T. Einhorn* and H.W. Caspari
Western Colorado Research Center, Colorado State University, Grand Junction, Colorado
81503, USA
Abstract
As part of a larger, multi-site study on Deficit Irrigation (DI) and Partial
Rootzone Drying (PRD) of apples (see abstract by Caspari et al.), a multi year
experiment was designed using ‘Gala’ on M26 to determine the effect of DI and PRD on
water use, fruit and shoot growth, yield, fruit quality, stomatal conductance,
transpiration, leaf water potential, and whole-leaf abscisic acid (ABA) concentration.
Irrigation was via two drip lines, one either side of the tree row. There were five
irrigation treatments: a well watered Control, 25 PRD, 50 PRD, 75 PRD and DI. For
PRD, the numbers represent the percentage of irrigation volume relative to the control
as well as the proportion of the surface area wetted by irrigation. The DI received 50%
of the irrigation volume applied to the control, but irrigation was applied to the whole
surface area. Water savings of 50% and 25-75% were achieved under DI and PRD,
respectively, without negatively impacting fruit size. Total seasonal irrigation volumes
were 198 mm, 160 mm and 122 mm for the 75 PRD, DI and 50 PRD, and 25 PRD
treatments, respectively. Fruit growth rate, final fruit size, and fruit quality at harvest
and after cold storage did not differ between treatments. Compared to published data,
we found very low midday values for stomatal conductance and transpiration rates at
comparatively high (less negative) leaf water potentials. Effects of several feed-forward
processes on apple hydration status in response to high diurnal VPD values (4-6 KPa)
and whole leaf ABA concentrations will be presented.
*Mailing Address: Department of Horticulture and Landscape Architecture, Colorado State
University, 111 Shepardson Bldg, Fort Collins, CO 80523-1173, USA
Telephone: (970) 491-7019, Fax: (970) 491-7745, E-Mail: [email protected]
40
A simple model for sound fertigation management under greenhouses in
Lebanon
Maroun EL MOUJABBER
Faculty of Agricultural Sciences, Holy Spirit
University Kaslik
e.mail: [email protected]
Thérèse ATALLAH
Faculty of Agricultural Sciences, Lebanese
University, Beirut
Talal DARWISH
Lebanese National Council for Scientific
Research, Beirut
Abstract
Lebanese growers have adopted protected agriculture because it insures a high
productivity mainly off-season, an important added value of their products and allows
the valorization of small land properties (less than 2 ha) which cover more than 46% of
Lebanese farmers. However, a lot of work should be done in terms of fertigation
management, practice widespread among farmers. The objective of this study is the
establishment of a simple model using climatic data outside the greenhouse for
fertigation management. For this reason, several studies were carried out to the
determination of water and fertilizers requirements of main protected crops in
Lebanon: tomato, cucumber and lettuce. Water consumption was correlated to outside
ETo and a coefficient relating plant growth (LAI or plant height) to outside
temperature was established. Results showed that despite the variation of the growing
season, the model gave good results and savings in water and fertilizers were observed
in addition to an increase in yield, decrease in production costs and important reduction
in soil salinity and nitrates leaching.
41
Subsoil Citrus Irrigation with Reclaimed Sewage Water
Y. Erner*, A. Bar-Tal, S. Asulin, E. Tagari, M. Keinan and M. Rozner.
ARO. The Volcani Center, P.O.B. 6, Bet-Dagan 50250, ISRAEL.
[email protected]
Abstract
Reclaimed sewage water is becoming an important source for agriculture usages
in many countries. Citrus, in most cases, can utilize the nutrients dissolved in water and
thus the trees and the soil system can serve as bio-filter to minimize the pollution of
underground water. Subsoil drip irrigation is the recommended method for effluent
application by the Israeli Ministry for Health. The overall goal of the study was to
develop irrigation scheme of secondary effluent to minimize ground water pollution
with optimal fruit yield. An experiment was conducted on a sandy to sandy loam soil, on
a ‘Star Ruby’ red grapefruit with: 1) reclaimed and fresh water 2) surface and subsoil
drip irrigation 3) one and two laterals 4) two quantity levels of water and 5) and two
irrigation intervals. Each treatment consists of 6 replicates with 4 weighing trees. The
drip laterals are placed 75 cm offside the trunk at surface or at a depth of 25 cm. The
emitters have a discharge of 3.8 l h-1 and are spaced at 50 cm intervals.
Yields were not affected by reclaimed water but decreased vegetative growth.
Low water quantity significantly reduced fruit size, yield and vegetative growth. Nonsignificant differences were found between irrigation intervals on yield as well as with
one or two laterals. During the irrigation period salt accumulation was found at the first
30cm with significant more salt at reclaim treatments. Soil soluble inorganic salts at the
end of rainfall, up to 150 cm depth, were similar at all treatments while deeper in the
soil, reclaimed water increased the inorganic salts, especially chloride and sodium. Two
laterals with daily irrigation and low water amount decreased water loss beneath the
root system. Subsoil drip irrigation had no adverse effect on yield or water loss beneath
the root system.
42
Slope and Aspect Effect on Evaporation as Measured by Atmometer
B.A. Faber
University of California
Cooperative Extension
Ventura, CA
USA
Abstract:
Atmometers were installed on four quadrants of a hill and at three positions on
the slope - toe, mid-slope and top of hill. There was clear fetch of over 1 kilometer in all
directions. The hill was within 2 kilometers from the ocean which was the prevailing
wind direction. Measurements were made over an eight month period from late winter
to fall in New Zealand. Wind played a dominant role in evaporative loss. Depending on
the season, evaporative loss was affected more or less significantly by slope aspect. On
most quadrants in most seasons, greatest evaporative loss occurred mid-slope.
Leaf and Canopy Light Reflectance in Relation to Water Content in Apple
O. Facini, S. Loreti, F. Rossi
Istituto di Biometeorologia
Consiglio Nazionale Ricerche
Via Gobetti 101 - Bologna, Italy
C. Bignami
Dipartimento di Produzione Vegetale
Università degli Studi della Tuscia
Via S. C. De Lellis - Viterbo, Italy
Abstract
The relationship between spectral light reflectance and leaf water content has
been established for several species giving a sound basis to the use of canopy
reflectance features measured by means of remote sensing technologies to detect water
stress of natural vegetation and crops. Nevertheless few data are available for fruit tree
species. The leaf and canopy reflectance features as indicators of plant water status
have been investigated in apple trees (cv Golden Delicious) grown in pots under
progressive water stress. While the reflectance in the visible wavelengths was stable,
some increase in this optical feature was observed in the 900-1000 nm spectral band
when relative water content decreased from 90.4 % to 85.4 %. These differences
dramatically increased when further decreases in RWC up to 40.6 were induced in
detached leaves, highlighting the absorbing rule of water in the near infrared region.
These results may provide useful indications on spectral responses of apple trees to
water stress, thus allowing the development of canopy reflectance models and a transfer
to irrigation management.
43
Developing an Automatic Controller for High Frequency Irrigation in
Fruit Tree Orchards
J.E. Fernández, F. Moreno and I.F. Girón
Instituto de Recursos Naturales y
Agrobiología, Apartado 1052, 41080-Sevilla,
Spain
Candil
Abamar Soluciones S.L., C/ Fuselaje, n.º 11,
41020-Sevilla, Spain
Abstract
The currently available irrigation controllers for commercial fruit tree orchards
need to be fed with information on the required irrigation dose. The aim of this work is
to design and test a controller able to calculate the irrigation dose automatically, and
suitable for high frequency irrigation. The controller, named CRP, is intended to
calculate the irrigation dose daily, from sap flow readings in the stem of representative
trees of the orchard. The trees, therefore, are used as biological sensors, and
information from the water status in the soil or in the atmosphere is not required. A
prototype of the CRP is being built, consisting on three (replicates) measuring units
(UM), a control unit (UC) and a radio-transmission system for communicating the UMs
with the UC. The prototype is going to be tested during the irrigation season of 2003
(April-September), in the olive orchard of the experimental farm La Hampa, close to
Seville, Spain. The orchard is planted in 34-year-old Manzanillo olive trees at a spacing
of 7 m × 5 m. Some 0.3 ha of the orchard will be irrigated following the FAO method,
i.e. calculating the crop water needs from the potential evapotranspiration in the area
and with a crop coefficient, which monthly values have been previously validated for
the orchard. A nearby plot of similar size will be irrigated by the CRP. The device uses
the compensation heat-pulse technique for determining the sap flows. We calibrated
this technique for olive in a former work. To what extent the CRP could be a suitable
tool for optimizing water use in the orchard will be evaluated by comparing a) the daily
irrigation doses calculated by the CRP and with the FAO method, b) the seasonal
evolution of the soil water content in both plots, and c) the water status of the trees, as
estimated from stem water potential readings, as well as phenological stage and growth.
44
Combining techniques to study evapotranspiration in woody crops:
application to small areas - two case studies
M. Isabel Ferreira and Teresa A Paço
Instituto Superior de Agronomia, UTL,
Tapada da Ajuda, 1349-017 Lisboa, Portugal
[email protected]
José Silvestre
Estação Vitivinícola Nacional, 2565-191
Dois Portos Portugal
Abstract
Information on water use of woody crops is scarce because of experimental and
modelling limitations related to the size and structure of roots and shoots. The eddy
covariance (EC) micrometeorological method is considered relatively reliable and
adequate, but it requires large uniform areas. The alternative is the use of sap flow (SF)
methods to quantify transpiration (T), often the dominant component of
evapotranspiration (ET). If up-scaling is often a challenge in very sparse stands, the
anisotropy of woody irrigated crops is not a major limitation. They also allow the
distinction between T in small plots, submitted to different treatments (in relation to
water, fertilizers, pruning, etc). However, none of the sap flow methods seems to be able
to provide good absolute values in all circumstances. This paper shows the use of a
combination of EC and SF methods, to quantify ET of small areas, using two case
studies. One is a peach orchard where ET could be obtained for the periods between
irrigations and also for different treatments (during stress cycles). The other application
has been made in a vineyard where 3 locations (3%, 10% and 17%) facing the same
orientation were compared in relation to water use, along a vegetative cycle. The results
show how the strategy used provided results of good quality in an appropriate time
scale, allowing also to follow the differences between the situations under study.
45
Effect of Water Stress Applied at different Development Periods of
Chardonnay Grapevine on Production and Wine Quality
R. Ferreyra, G. Selles, R. Ruiz and I. Selles
Instituto de Investigaciones Agropecuarias.
Casilla 439, correo 3. C.P. 7083150. Santiago. Chile.
[email protected]
Abstract
Water stress treatments were applied to Chardonnay vines during the 1998/99
to 2000/01 season in the Casablanca Valley, Chile. Four treatments were applied : T1,
100 % of crop evapotranspiration (ETc) all over the season , T2 , 50% of ETc all over
the season, T3, no irrigation from bud- bursting to veraison, followed by 100 % ETc
until harvest, and T4, 100 % ETc from bud-bursting to veraison and no water until
harvest.
Stem water potential (ΨS) measured at midday shows difference between
treatments, it was around -0,7 MPa in T1 and -1,2 MPa in T3, at the end of drought
period. Water stress reduced vegetative growth and berry size, affecting plant yield and
root carbohydrate reserves, particularly in T3 treatment (without irrigation between
bud-bursting and veraison). Nevertheless, no effects on wine quality between
treatments were measured. Total acidity and phenols content were similar in all of
them.
46
A Daily Water Balance Estimate for Climate Risk Evaluation at a Local
Scale
M. Fiori 1 and A. Motroni
Agrometeorological Service of Sardinia,
SAR, Sassari, Italy
P. Duce
National Research Council, Institute of
Biometeorology, IBIMET, Sassari, Italy
D. Spano
Department of Economics and Woody Plant
Ecosystems (DESA), University of Sassari,
Italy
Abstract
A methodology for calculating a regional soil-water balance based on
climatological and pedological data of Sardinia (Italy) is presented. Daily temperature
and rainfall data from reference period 1971-2000 were spatially interpolated on a 10
km x 10 km cell grid to obtain a set of homogeneously distributed values. Pedological
information of Sardinian soils were used to characterize the entire territory of Sardinia
in terms of available water content (AWC) and soil depth. Reference
evapotranspiration values (ETo) were estimated using the Hargreaves method and
actual evapotranspiration estimates (ETa) were calculated as function of soil water
content for each grid cell. A simplified soil water balance was calculated for each grid
point and year to determine the average daily soil water content over the thirty-year
period. Climatic risk was evaluated considering the number of days when soil water
content was below a certain threshold (25 % and 50 % of available water content) for
each year of the 1971-2000 period. Results showed a wide variability of interannual
climatic and water deficit conditions throughout the region. Maps of spatial distribution
of drought conditions showing climatic risk for agricultural activities are presented.
47
Soil Wetting Pattern Monitoring and Irrigation Scheduling as Key Factors
for Water Use Efficiency under RDI and PRD
S. Fuentes1
Centre for Horticulture and Plant Sciences
(CHAPS). University of Western Sydney.
Locked Bag 1797. Penrith South DC. 1797.
Sudney. Australia. E-mail:
[email protected].
G. Rogers2
AHR Crop Science. Room N222 Woolley
Building, University of Sydney, NSW 2006,
Australia. Postal: PO Box 552. Sutherland
NSW 2232, Australia. Email:
[email protected].
Website: www.ahr.com.au.
Key words: Partial rootzone drying; soil moisture monitoring; 3D image; grapevine.
Abstract
A major challenge for irrigation technology in many countries is how to best use
scarce water resources for crop irrigation. Competing alternative humanitarian uses for
water make it imperative to optimise the efficiency of irrigation water delivery to crops.
Irrigation scheduling has become more challenging since the development of new
irrigation technologies to optimise water use efficiency, such as Regulated Deficit
Irrigation (RDI) and Partial Rootzone Drying (PRD) have created narrow soil moisture
and plant stress target thresholds. This in turn requires accurate monitoring of both
the soil water storage in the root zone and crop water stress levels. A field study was
carried out to visualise the wetting pattern in situ on a Grapevine site (Vitis vinifera
var. Shiraz) at the University of Western Sydney (Richmond N.S.W.). A set of 36
capacitance sensors distributed over one quarter of the total soil area available to the
vine (1.75 m2) were installed at 10, 20, 30 and 50 cm of depth in 9 measurement points
close to a PRD subsurface irrigation system. A further 28 sensors were used to monitor
soil moisture in a comparative surface drip irrigated system. Soil moisture data
collected was used to generate progressive 3D images of wetting patterns at different
irrigation scheduling programs. Plant water status was monitored by measuring: leaf
water potential (Scholander bomb); leaf gas exchange and stomatal conductance using a
LiCor 6400. Preliminary results have shown the importance of the location of soil
moisture sensors to schedule irrigation. It is also very important, to have a plant-based
water status-monitoring system to complement soil moisture assessment. Infra-red
thermography has been used in an attempt to estimate stomatal conductance. The
implementations of soil moisture and plant stress based measurements are viable means
for managing large irrigated areas with an increasing use of new irrigation techniques
such as RDI and PRD.
48
Response of Stem Diameter to Water Stress in Greenhouse-grown
Vegetable Crops
M. Gallardo and R.B. Thompson
Depto. de Producción Vegetal, Universidad
de Almeria, 04120, Almeria, Spain
Mª.D. Fernández
Cajamar E.E. Las Palmerillas, Apdo. 250,
04080 Almeria, Spain
Abstract
In transpiring plants, stem diameter normally undergoes diurnal fluctuations,
with maximum values shortly before sunrise, and minimum values in the early
afternoon. Maximum daily contraction (MDC) is a sensitive indicator of water stress in
some fruit tree species. This work assessed the sensitivity of MDC in tomato and melon
grown in plastic greenhouses in Almeria, Spain. Both crops were grown in soil, with
drip irrigation. In each crop, there were two treatment, a well-watered treatment based
on the use of soil moisture measurement (tensiometers or capacitance system), and a
water-stressed treatment where irrigation was withheld for specific periods. The
tomato was transplanted on 7/09/00, the melon on 22/02/01. Until the imposition of
treatments, all plants were well-watered. Water was withheld in the tomato from 3/4/01
to 10/4/01, and in the melon from 17/05/01 to 23/05/01. In each treatment, two plants
were monitored using linear variable displacement transducer sensors (SD-5, Phytech
Ltd., Israel). In both species, within 48 h of withholding irrigation, MDC was clearly
larger in "water-stressed" than compared to "well-watered" plants. The differences
were maintained until the day after resuming irrigation. For "well-watered" plants, in
both tomato and melon, there was a strong linear relationship between MDC and
vapour pressure deficit (VPD). Normalised MDC (i.e. MDC divided by VPD) was
relatively constant in "well-watered" plants, for both melon and tomato, with values of
14–20 µm kPa-1 for tomato, and 3–9 µm kPa-1 for melon. Normalised MDC increased
rapidly after with-holding water; within 48 h, values were 34 and 25 µm kPa-1,
respectively, for tomato and melon. Similar values were maintained during the
treatment period. Twenty-four hours after resuming irrigation, normalised MDC
returned to values similar to those of well-watered plants. These data suggest that
normalised MDC may be a sensitive indicator of plant water status of vegetable crops
grown in greenhouses.
49
Investigating Crop Coefficients in Orange Drip Irrigation
C. Germana,
Department of OrtoFloroArboricoltura e
Tecnologie Agroalimentari
University of Catania, Italy
V. Sardo
Department of Agricultural Engineering,
University of Catania, Italy
Abstract
During two successive years seven different crop coefficients (Kc) were applied
in the management of a drip system to irrigate a mature orange grove in Sicily.The
volume of water application was determined multiplying the evaporation values from a
class A evaporimeter by Kc values ranging from a constant 0.4 to a constant 0.7, and
including values variable in time from 0.4 to 1.2, plus a treatment where Kc was weekly
changed according to pre-dawn xylem potential (the “physiological treatment”). The
total seasonal volumes of applied water, averaged over the two years, ranged from a
minimum of 2.022 m3/ha (with a constant Kc of 0.4) to a maximum of 3.548 m3 /ha
(with a constant Kc of 0.7). Plants receiving more water showed the highest total fruit
weight with the largest fruit size, and had also the highest increase in trunk diameter.
The best water use efficiency, namely the ratio of yield to applied water, was achieved in
two treatments: the constant Kc 0.4 and the “physiological treatment”. The unit fruit
weight as well as fruit size were negatively correlated with the number of fruits, which
however positively impacted the total production; these results give a support in finding
a trade-off in citrus irrigation management between yield quantity, fruit size and water
volume in order to maximize profit and save resources.
50
Determining when to Initiate Irrigation of Orange Trees
C. Germana,
Department of OrtoFloroArboricoltura e
Tecnologie Agroalimentari
University of Catania, Italy
V. Sardo
Department of Agricultural Engineering,
University of Catania, Italy
Abstract
In order to evaluate the accuracy of currently adopted practices in determining
the moment of initiation of the irrigation season for orange crops and the impact of a
delayed initiation on fruit setting a research was conducted by simultaneously
monitoring water status in soil and plants, in a mature drip irrigated orange grove. Soil
water status was monitored through the installation of a couple of mercury
tensiometers per plant at the depth of 60 cm, while plant water status was monitored
through the use of the pressure chamber. Three threshold values of soil matric potential
were selected to initiate the irrigation, namely 30, 50 and 70 kPa (treatment A, B and C,
respectively) as resulting from the averaged readings in three plants per treatment, i.e.
from six tensiometers. Xylem potential was weekly monitored before dawn sampling
three leaves per plant in the same plants where tensiometers were placed and as a
consequence the weekly averaged value resulted from nine readings per treatment;
additionally, xylem potential was occasionally monitored throughout the entire day. The
date of initiation in the three treatments was May 27, June 11 and June 25 in treatment
A, B and C. Rainfall occurred in May 27 but no precipitation occurred thereafter till
September. Plants in treatment B recovered soon from the water stress, approaching
values of xylem potential on those of treatment A whereas plants in treatment C
reached the same levels of those in the other treatments only by August; the trends in
xylem potential also confirmed that drip application with a single lateral and a dripper
spacing of 1 metre is insufficient to adequately irrigate previously sprinkler-irrigate
mature orange plants. Fruit setting was significantly but non dramatically affected by
the treatments: the relative values resulted 100, 86 and 84, in treatment A, B and C,
respectively; water savings in treatments B and C were also significant.
51
Bulb Placement Effects on field - grown shallot (Allium cepa var.
ascalonicum Baker) using Conventional Furrow Irrigation and Rainfed
Production
Dessie Getahun1and Mesfin Ameha
1Ethiopian Agricultural Research Organization
Debre Zeit Agricultural Research Center
POBox 32, Debre Zeit, Ethiopia
Tel: 251-1-338555 Fax: 251-1-338061
Email:[email protected]
Abstract
Shallot (Allium cepa var ascalonicum Baker.) is the favorite and widely grown
Allium in Ethiopia. It is used daily in the preparation of 'Wot'- a stew eaten with
"Injera" (Ethiopian fluffy thin flat bread / pancake).
Shallots are commonly propagated by bulb and usually produced in the dry
season with irrigation. The practice of land preparation associated with the
characteristics of soils and the methods of bulb placement have been observed to be the
major factors contributing to inconsistency in growth and decline in yield of shallot.
A field study was conducted on light soil (sandy clay loam) and Vertisol (black
clay soil) with the objective of determining the most appropriate bulb placement
position for conventionally furrow irrigated (dry season) or rain-fed (rainy season)
shallot production. Eight different bulb placement practices namely top, side and basal
bulb placement at planting; flat land planting with top, side and basal placement after
sprouting, and conventional bulb placements (flat land planting along and across the
slope followed by immediate ridging) were evaluated at Debre Zeit, Ethiopia using local
shallot cultivar, DZSHT-78.
In the conventional furrow irrigation shallot production, placement of bulbs at
sides of ridges produced significantly higher yield (13.3 t/ha) than the other treatments.
No statistical yield difference among bulb placement treatments was obtained under
rain-fed production, although the highest yield was from side placement of bulbs.
Conventional bulb placement methods (flat land plantings across and along the
slope followed by immediate ridging) sprouted lower than the others and is reflected in
significantly low average fresh bulb yield, 10.6 and 10.4 t/ha, respectively.
52
Pear crop coefficients obtained in a large weighing lysimeter.
Girona, J., Marsal, J. Mata, M., Del Campo, J.
Àrea de Tecnologia Frutícola, Centre UdL-IRTA.
Rovira Roure, 177. 25198 Lleida (Spain).
e-mail: [email protected] web: www.irta.es
Abstract
In a large weighing lysimeter, with 3 pear trees planted in 1999 (cv
“Conference”) at 4 x 1.6 m, and located on the center of a 4000 m2 pear plot, was used
to determine hourly pear water consumption (ETc). The lysimeter container has an
area of 9.5 m2 and a depth of 1.65 m (minimum). The container is located over 4 load
cells with an individual capacity of 15 tm, which gives to the lysimeter a total weight
capacity of 69 tm. The weighing sensitivity is 0.5 kg and the lysimeter sensitivity is 0.053
mm. Close to the lysimeter there is an automatic weather station that determine hourly
the ETo. Pear crop coefficients were determined as a ETc/ETo ratio.Weekly evaluations
of proportion light interception (LI) using a Ceptometer at solar noon, were correlated
with the previous determined Kc finding the following equation:
Kc = 0,1298 x e5.9481 x LI
(R2 = 0.9798).
53
Vineyard Response to different Irrigation Strategies
Girona, J., Mata, M., Del Campo, J., Arbonés, A. and Marsal, J.
Àrea de Tecnologia Frutícola, Centre UdL-IRTA.
Rovira Roure, 177. 25198 Lleida (Spain).
e-mail: [email protected] web: www.irta.es
Abstract
The experiment was conducted in 2001 and 2002 in a commercial vineyard (Vitis
vinifera L.) of 12 year-old “Pinot-Noir” vines (1.7 x 3.10 m spacing)(1900 vines/ha)
located in Raïmat-Lleida (Spain). The soil was a clay loam with an effective rooting
depth between 90 and 110 cm. Annual rainfall for 2001 was 414 mm. Daily maximum
temperature was about 36 ºC.
Irrigation water was supplied through a drip irrigation system with two 2.3 L/h
drippers per vine located in the row and equally distributed trough the pipe. The
system was operated with one general controller that individually manipulates each one
of the selenoid valves located in each experimental unit. The irrigation schedule was
introduced daily to the controller.
Four irrigation treatments were applied: three vine water status irrigation
(VWSI) strategies and the farmer strategy (FS) . First year FS was based on the water
budget approach (Goldhamer and Snyder, 1989), with data from a weather station close
to the experimental field which determine the reference evapotranspiration (ETo) using
the FAO modified Pemman equation (Doorenbos and Pruitt, 1977) and the estimated
crop coefficient (Kc) adapted from Williams et al., (1994), and second year FS was
adapted to be close to one of the VWSI. Additionally three VWSI treatments were
imposed based on to irrigate with 4 mm/day the vines of one experimental unit each
time that midday leaf water potential (ψmd), daily measured, was lower than the
established threshold defined for each one of the VWSI treatments: 1) Control (VWSIC) ( C ) irrigated when ψmd was lower than –0.8 MPa for the full season , 2) Control Stress (VWSI-CS) (CS) irrigated like VWSI-C from bud-break to middle of June (about
middle of fruit growth stage II), and from that to harvest when ψmd was lower than –1.2
MPa, and 3) Stress (VWSI-S)(S) irrigated when ψmd was lower that –1.5 MPa from budbreak to middle of June and thereafter to harvest when ψmd was lower than –1.2 MPa.
After harvest the three VWSI treatments were still irrigated until early October
following the lasted guidelines.
Berry growth, yield (total yield and yield parameters), juice quality, vegetative
growth and plant water status, were clearly affected by the irrigation imposed.
54
Validation of Irrigation Scheduling Protocols Using Trunk Diameter
Sensors on Almond Trees
David A. Goldhamer
Department of Land, Air, and Water Resources
Kearney Agricultural Center
University of California
9240 South Riverbend Avenue
Parlier, CA 93648, USA
Elias Fereres
IAS-CSIC
University of Cordoba
Apdo. 4084
14080 Cordoba
SPAIN
Abstract
Use of plant indicators for irrigation scheduling may be the ideal method but it is
hampered by the difficulties in capturing the dynamic nature of plant water status
relative to the reliability of established scheduling methods based on atmospheric and
soil observations. A study was conducted in an almond (Prunus dulcis (Mill.) Webb)
orchard located in the San Joaquin Valley of California during the 2001 season using
trunk diameter variations as the only indicator for determining the amount of
irrigation. The ratio of the maximum daily shrinkage (MDS) of tree trunks relative to a
reference MDS, calculated from a relationship between MDS of fully irrigated trees and
atmospheric vapor pressure deficit, was used as a signal for modifying the amount of
applied irrigation water. Applied water was increased by 10% each time the MDS
signal exceeded the prescribed threshold. When the MDS signal went below the
threshold, applied water was reduced by 10% in an interactive manner. Two schedules
were tested with signal thresholds of 1.75 and 2.75. The two irrigation treatments had
stem water potential (SWP) that varied over the season from around –0.7 to –1.1 MPa
and –0.8 to –1.7 MPa, respectively. Applied water to harvest was 525 and 860 mm for
the 1.75 and 2.75 signal threshold treatments, respectively, compared with 900 mm for
the grower/cooperator, who based his schedule primarily on SWP measurements.
Estimated crop evapotranspiration was 1030 mm. The stress produced by the
irrigation treatments hastened fruit maturation, as evidenced by accelerated hull
splitting. This resulted in lower fruit hydration just prior to harvest; 17.3 and 8.0% for
two irrigation schedules, respectively, compared with 27.3% for the grower/cooperator.
Based on harvesting selected trees with the same nut load, fresh and dry nut weights in
the 2.75 threshold treatment were 9.0 and 10.7% less, respectively, than those of the
1.75 threshold, which were not significantly different than the cooperator. Our results
demonstrate that it is feasible to develop an irrigation schedule for almond trees based
solely on MDS signals, which may be tailored to any desired stress pattern and be
operated in full automation with the appropriate software development.
55
The relationship between peach tree water use and effective canopy cover
I. Goodwin
Department of Primary Industries
Private Bag 1, Tatura, Victoria 3616
Australia
Abstract
A short-term experiment was conducted at Tatura, Australia to determine the
effects of reducing tree size on peach tree water use (PTWU) for an isolated well
watered field grown tree. Tree size was progressively reduced by de-branching over a
period of 15 days in March 2001. PTWU was estimated from 15-minute measures of
heat pulse velocity at sixteen positions in the trunk sapwood. Reference crop
evapotranspiration (ETo) was determined from meteorological data collected in a
nearby automatic weather station. Peach Kcb was calculated as the ratio of PTWU to
ETo. The area of shade cast by the tree on the soil surface (Ash) was estimated prior to
each de-branching event at approximately hourly intervals throughout the daytime by
digital photographs of the projected sunlit leaf area and the fraction of PAR intercepted
by the tree. Effective canopy cover (ECC) was taken as Ash at solar noon. Both PTWU
and ECC declined with the reduction in tree size. There was a strong positive linear
relationship between Kcb and ECC (Kcb = 1.5 x ECC). These results suggest that PTWU
in an orchard may be estimated from a simple measure of the shaded ground area (ie.
ECC) and ETo. Implications for irrigation management are discussed.
56
Limitations in Hydraulic Conductance Regulate Water Use and Water Use
Efficiency of different Grapevine Canopy Systems
Bernd R. Gruber and Hans R. Schultz
Institut für Weinbau und Rebenzüchtung
Forschungsanstalt D-653660
Geisenheim, Germany
Abstract
Some grapevine trellising systems such as minimal pruning (MP) show potential
for higher sugar yields per hectare as compared to the commonly used vertical shoot
positioned system (VSP) because of a more rapid canopy development and a higher leaf
area index (LAI). This high LAI may become problematic when water becomes
limiting. Sap flow measurements over several complete growing seasons showed that
water use was higher for individual plants of the MP as compared to the VSP system,
but similar per m2 of soil surface area. Additional measurements of leaf (LWP) and
stem water potential to calculate whole-plant hydraulic conductance (Kh) revealed
similar upper limits of Kh for both canopy systems. The higher flow rates in the MP
vines despite similar Kh could only be sustained through more negative diurnal trends
in LWP at similar soil water potentials. Photosynthetic rates of leaves in their natural
position and located in canopy zones exposed to photosynthetic photon flux density
(PPFD) values close to light saturation were slightly lower in the MP as compared to
comparable leaves in the VSP system, which was probably related to the lower LWP.
However, diurnal photosynthetic rates in canopy zones exposed to sub-saturating PPFD
were similar for both systems. The data suggested that water use efficiency of exposed
leaves of MP vines was improved because of limitations in their hydraulic system. In
addition to possible anatomical differences in the water pathway, diurnal changes in Kh
also correlated with cavitation events in shoots and leaf petioles measured
concomitantly with an ultrasound acoustic emissions detector.
57
The Effect of Irrigation on Fruit Development of Olive Cultivars ‘Frantoio’
and ‘Leccino’
R. Gucci, S. Gentile, M. Serravalle, F.
Tomei.
Dept. Coltivazione Difesa delle Specie
Legnose, University of Pisa,
Pisa 56124, Italy.
H.F. Rapoport
Instituto de Agricultura Sostenible, C.S.I.C.
P.O. Box 4084
14080 Córdoba, Spain.
Abstract
Regulated deficit irrigation (RDI) strategies are becoming widely used in olive
groves. To apply RDI correctly we need to know how water availability in the soil
affects fruit growth and development. A two-year study was conducted on field-grown,
mature trees of two olive cultivars (‘Frantoio’ and ‘Leccino’) in Tuscany (Italy) to
assess the effect of irrigation on fruit growth parameters and cellular processes
determining mesocarp growth. Reference evapotraspiration, calculated by the PenmanFAO equation, was multiplied by a crop coefficient of 0.55 and 0.65 to determine the
amount of irrigation water. The fresh weight, dry weight and volume of fruits and their
tissues were monitored at approximate two-week intervals in both years. At 9 (end of
massive endocarp sclerification), 18 and 20 weeks after full bloom (AFB) fruits were
sampled for anatomical observations and transverse equatorial sections were measured
using an image analysis system. Fruits from irrigated trees showed greater weight,
volume, mesocarp transverse area, and endocarp volume than those from rainfed trees
of both cultivars at 9, 18 and 20 weeks AFB. Irrigation significantly increased the size of
mesocarp cells of cv. Leccino at 9, 18 and 20 weeks AFB, but that of cv. Frantoio only at
20 weeks AFB. The number of cells in transverse equatorial sections of cv. Frantoio was
increased by irrigation at 9 and 18 weeks AFB.
58
Oil Quality of Olive cv. ‘Leccino’ under Irrigated or Rainfed Conditions
R. Gucci
Dept. Coltivazione Difesa delle Specie Legnose, University of Pisa, Italy;
M. Servili, S. Esposto, R. Selvaggini
Dept. Scienze degli Alimenti, University of Perugia, Italy.
Abstract
Despite the increasing use of irrigation in olive groves, there is still a poor
understanding on the effect of irrigation on qualitative parameters of olive oil. A twoyear study was conducted on field-grown olive trees (cv. ‘Leccino’) in Tuscany (Italy) to
assess the effect of irrigation on oil yield and quality. Reference evapotraspiration,
calculated by the Penman-FAO equation, was multiplied by a crop coefficient of 0.55
and 0.65 to determine the amount of irrigation water. Fruits were harvested at the stage
of full pigmentation of the epicarp only (plot 1) and green color (plot 2). Free acidity,
peroxide number, K232, K270 and fatty acid composition were measured using official
methods of analysis, volatile compounds by SPME-GS-MS, and phenolic compounds
were assayed colorimetrically. Irrigation did not affect free acidity, peroxide number
and fatty acid composition of oils. The oleic acid ranged from 74.3 to 77.5% of total
fatty acids in oils from rainfed and irrigated trees, respectively. Irrigation decreased
total phenols and ortho-diphenols of oils from plot 1, but not those from plot 2, and
increased several volatile compounds related to virgin olive oil flavour in both plots.
Irrigation decreased pungency and bitterness and increased fruity apple flavours of oils
from plot 1. Oils from irrigated trees of plot 2 showed greater fruity apple and floral
attributes than those from rainfed trees.
59
Non Destructive Measurement of Water Interception of Plant Canopies by
using Gamma-scanning-technique
Bodo Gutezeit
Institute of Vegetable and Ornamental Crops, Grossbeeren/Erfurt
Theodor-Echtermeyer-Weg 1, D-14979 Grossbeeren, Germany
(e-mail: [email protected])
Keywords: Sprinkler irrigation, radiometric measured plant mass, ratio of interception,
spatial distribution of intercepted water, Spinacea oleracea L.
Abstract
An estimate of water losses caused by canopy interception is required to
calculate soil water balances or to parameterize models of crop water demand.
Moreover plant pathologists are interested in time courses of canopy wetness in
dependence on climatic conditions. The present paper describes a gamma ray
absorption technique combined with a scanning device, that allows to measure nondestructively the quantity and spatial distribution of intercepted water in a crop
canopy. Measurements were made on spinach (Spinacea oleracea L. var. foliosum Hegi
`Boeing´) canopies, treated with different amouts of irrigation water supplied by
sprinklers. The amount of intercepted irrigation water, which adheres to the surfaces of
leaves and stems, was estimated by calculating the difference of radiometric measured
plant mass, before and a few minutes after irrigation. The quantity of intercepted
irrigation water increased during canopy development, i.e. with increasing plant
surfaces. For plant masses from 2.0 to 5.0 kg per m² the ratio of interception increased
from 5% to 11% when 7 mm water was applied and from 1% to 4% when 21 mm water
was supplied, respectively. Further analyses will make it possible to resolve the spatial
distribution of intercepted water on separate canopy layers. The results of this
experiment showed that the gamma-scanning technique was able to measure the
amount of water intercepted by a spinach canopy within the error of smaller than 5%
for fresh plant masses about 0.100 kg per m², while those more than 1.250 kg per m²
with an error smaller than 1%. The benefits of this method, which could be taken
continuously at small time intervals on the same canopies, made it possible to assess the
interception in dependence on irrigation or precipitation on vegetable, agricultural and
ornamental plants.
60
Evapotranspiration of Processing Tomato under Subsurface Drip
Irrigation and Sprinkler/Furrow Irrigation
Blaine Hanson
Dept. of Land, Air and Water Resources
University of California
Davis, CA 95616 USA
Email: [email protected]
FAX: 530-752-5262
Abstract
It has been hypothesized by those involved in re-allocating water in California
that converting from furrow/sprinkler irrigation to subsurface drip irrigation would
reduce evaporation losses from the soil and result in a real water savings. However,
little or no information is available on the potential of subsurface drip irrigation for
reducing evaporation from the soil. Thus, evapotranspiration of processing tomato was
determined for subsurface drip-and furrow/sprinkler-irrigated fields to assess the
potential of subsurface drip irrigation for reducing these evaporation losses. Fields
containing subsurface drip irrigation and furrow/sprinkler irrigation systems were
selected along the west side of the San Joaquin Valley of California. Evapotranspiration
at each site was determined with the Bowen Ratio Energy Balance Method using the
Bowen Ratio system developed by Campbell Scientific, Inc. Measurements made by this
system include air temperature and water vapor pressure at two elevations above the
canopy, net radiation, wind speed and direction, soil temperature, soil heat flux, and soil
water content. In addition, canopy growth was monitored using a digital infrared
camera and appropriate software for calculating canopy coverage from the camera
images and soil moisture tension was monitored using Watermark electrical resistance
blocks. Crop coefficients of processing tomato were calculated for each irrigation
method using reference crop evapotranspiration from a nearby California Irrigation
Management Information System. Results of the first year showed about 69 mm more
evapotranspiration under the furrow irrigation system compared to the drip system.
The higher ET amounts occurred during the initial and rapid growth stages where
relatively small canopy coverage resulted in evaporation from the soil under
furrow/sprinkler irrigation. ET rates during the mid-season growth stage were similar
for both irrigation methods. Canopy growth was similar for both irrigation methods at
these sites. Results of the second year showed more ET under subsurface drip irrigation
compared with furrow/sprinkler irrigation. Similar ET rates occurred for both
irrigation methods during the initial and rapid growth stages because sprinkler
irrigation was used for stand establishment for both irrigation methods and careful
water management used for the furrow system to minimize surface wetting.
61
Economics of Four Irrigation
Viburnum odaratissium
Technologies
for
Container-grown
J.J. Haydu, Mid-Florida REC, 2725 Binion Rd, Apopka, FL 32703
R.C. Beeson, Mid-Florida REC, 2725 Binion Rd, Apopka, FL 32703
J. Caron, Dept. des Sols et de génie agroalimentaire, Université Laval, Ste. Foy, Quebec,
G1K 7P4, CANADA
Abstract
A capillary mat irrigation system was compared to micro-irrigation, a subirrigation tray, and an overhead sprinkler control to assess the economic costs and
returns of each system used in the production of container-grown Viburnum
odaratissium in 3.8 L containers. The economic analysis examined installation costs
associated with setting up each system and all production-related expenses required to
bring plants up to 92% marketability. Water use was monitored and cumulative
consumption for each treatment was converted from total gallons per system to a dollar
figure. For comparative purposes and simplification of analyses, expense data were
converted from physical units to dollar units per container. Yields, revenues and profits
were calculated for one-tenth hectare units and were totaled over six years to show a
cumulative dollar impact. At current market value per unit, irrigation volume was not
a significant factor in the profitability of any system. However plant growth rates
among systems, as influenced by water availability, substantially impacted positive
returns on investments.
62
Selected aspects of Crop Water Relations and Evapotranspiration – What
is Known and what is not Known?
T.C. Hsiao
University of California
Dept. of Land, Air and Water Res.
Davis, CA 95616
USA
Abstract
Considerable progress has been made in the last few decades in our
understanding of many aspects of crop water relations and in the development of
quantitative procedures for the estimation of crop water use. This presentation will
review a few topics selected from the many aspects, describing their recent
developments and what is controversial or not known, and their implications in terms of
crop water relation, water use, and irrigation management. The selected topics are: (a)
Differential sensitivity to water stress between leaf growth and root growth, the
underlying mechanisms, and its importance in crop adaptation to water deficit and in
yield determination. (b) Root/shoot signaling in response to water stress, whether the
signals are chemical or hydraulic in nature, and their likely role in determining benefits
arising from some deficit irrigation practices. (c) Role of stomata in controlling canopy
transpiration, the relation between canopy conductance and stomatal behavior, and the
extent control of transpiration by stomatal or canopy conductance is influenced by
coupling of the canopy with the atmosphere. (d) Photosynthetic water use efficiency in
relation to variations in intercellular CO2 concentration (Ci), the conservative nature of
(Ci), unexplored mechanism that maintains Ci constant, and recent evidence indicating
the importance of changes in Ci with humidity gradient in determining crop
coefficients.
63
The Response of Selected California Native Grass Species to Elevated Salt
Levels Administered by Sprinkler Irrigation
Kimberley Hunter, and Lin Wu
Department of Environmental Horticulture
University of California
Davis, CA 95616, U.S.A.
Abstract
Salt spray by sprinkler irrigation on plant canopies is the major concern in
recycled water irrigation and landscape management. Five grass species including
California melic (Melica californica Vasey), purple needlegrass (Nasella pulchra (A.
Hitchc.) Barkworth), alkali sacaton [Sporobolus airoides (Torrey) Torrey], deergrass
[Muhlenbergia rigens (Benth.) A. Hitchc.], and California hairgrass (Deschampsia
casepitosa (L.) Beauv.) that are commonly used in California landscapes and gardens
were examined for response to salt stress. The plants were grown in washed medium
particle size sand and in 90 cm deep, 16 cm diameter open-ended PVC cylinders in the
greenhouse. The plants were irrigated by sprinkler system with potable water (control),
500 mg L-1 NaCl (slightly above the upper level of salt concentration in most recycled
waters), and 1500 mg L-1 NaCl, (closer to salt spary in the costal environment). After 20
weeks growth, the percent leaf chlorosis were recorded. The plants were harvested, and
the above ground plant dry weight, root dry weight distribution at three soil depths,
root thickness (diameter), and sexual reproductive effort were measured. Salt tolerance
indices were calculated based on shoot or root dry weight. Leaf sap osmolality was
measured and tissue Na+1, Cl-1, Ca+2, and K+1 concentrations were analyzed. Under 500
mg L-1 salt treatment, no salt stress effect was detected in any of the five grass species
for the above parameters. Under 1500 mg L-1 salt treatment, although significant Na+1,
Cl-1, Ca+2, and K+1 uptake were detected in all the five species, but only M. californica
showed significant salt stress symptoms and reduced shoot growth, depressed
osmolality, and reduced root dry weight. The greater percentage of root dry weight
distribution in deeper soil depths was found to be associated with greater root thickness.
In conclusion, all the five grass species tested should be able to adapt to recycled water
irrigation. However, Melica californica should not be recommended in areas exposed to
salt spray where near the ocean or to irrigation water having salt concentrations above
500 mg L-1.
64
Continuous Measurement of Plant and Soil water status by Automated
Sensors for Irrigation Scheduling in Plum
D.S. Intrigliolo, J.R. Castel
Instituto Valenciano de Investigaciones Agrarias,
Dept. Recursos Naturales,
Apartado Oficial 46113, Moncada (Valencia), Spain
Abstract
The usefulness of continuous measurements of soil and plant water status for
automated irrigation scheduling was studied in a drip-irrigation experiment on plum
(Prunus salicina cv Black Gold) where two levels of water restriction were imposed at
different phenological periods (pit hardening to harvest and post-harvest). Soil matric
water potential (ψsoil) was measured with granular matrix sensors (WATERMARK)
and short period fluctuations of trunk diameter (TDF) with linear variable
displacement transducers (LVDT). From TDF measurements, maximum daily
shrinkage (MDS), evolution of maximum trunk diameter (MXTD) and trunk growth
rate (TGR) were calculated. Their performance was compared to discrete
measurements of midday stem water potential (ψstem). Results of Watermark sensors
showed good indication of plant water status during all the season (r2 = 0.56**), but
were highly variable (typical values of CV 35-50%). TDF parameters were better
related to ψstem and less variable in our conditions. During most of the fruit growth
period (Stages II and III), when trunk growth rate was minimum, MDS was higher in
the less irrigated treatments than in the control and well correlated (r2=0.89**) to
ψstem. However, after harvest, when TGR was higher, the correlation decreased
(r2=0.73-0.52**) and so did the slope (between MDS and ψstem) as the season progressed,
suggesting tissue elasticity changes, but then TGR differences between control and
stressed treatments were better related to plant water status. These facts indicate some
of the difficulties in obtaining reference values useful for irrigation scheduling using
TDF measurements.
65
Tensiometric Measurements : A Tool to Analyse Root Growth and to
Schedule Irrigation of Landscape Trees
Carole ISBÉRIE, Cemagref, Irrigation team, Aix-en-Provence, France
Abdelkader BENSAOUD, Irrigation Consulting Office, Le Plessis-Robinson, France
Abstract
In agriculture, there are strategies for scheduling irrigation using tensiometric
sensors. These strategies have been developed over more than 20 years, experimentally
verified, tested and put into agricultural practice. The problem of irrigation in
landscaped areas is unlike that of agriculture: urban soils are often thin layers of
reconstituted soil. Their role as a water reservoir is reduced even more by the fact that
their physical and chemical fertility is altered. Over the past ten years, efforts have been
made to understand how soil water works in anthroposoils in urban environments. The
special case of transplanted plants, such as trees, is accentuated by their insufficient
root absorption capacity: a tree transplanted into an urban environment suffers an
imbalance between its weak root absorption capacity and transpiration, since it loses
nearly 70% of its root system when it is dug up at the nursery. During four years an
experimentation was carried out to follow root growth of walnut trees (Juglans nigra)
with three procedures of irrigation: distance of 0.45 m or of 1.25 m between the
irrigation drain and the trees, and systematic irrigation at regular time intervalls, or
distance of 1.25 m and tensiometric scheduling. Tensiometric measurements appeared
to be a good indicator of root growth. So it could be possible to include tensiometric
monitoring in company consulting files as a contractual element. Even more, when used
as scheduling tools, tensiometric measurements allowed an important saving of
irrigation water. So, they have once again proven to be of great interest.
66
Using Information from Sap Flow Measurements to Improve Soil
Adaptability to Drip Irrigation in Orchards
ISBÉRIE Carole, Cemagref, Irrigation team, Aix-en-Provence, France
CABIBEL Bernard, INRA, SoilScience, Avignon, France
VALANCOGNE Charles, INRA, Bioclimatology, Bordeaux, France
AFONSO DO PAÇO Teresa, ISA, Lisbon, Portugal
Abstract
If the soil cannot store all the water needed for the crop in the wetted drip
irrigation "bulb", one possibility is to irrigate in the daytime, when the crop
evapotranspires the most. In this case the soil does not need to store the whole quantity
of daily crop water requirements, but only the cumulative difference between supplied
and consumed water at each moment. We have studied the example of an irrigation
during 16 hours per day, i.e. 8 l per hour, and a tree evapotranspiring 130 l /day. On the
basis of this exxperiment, it was possible to estimate the maximum and the minimum
amount of water that has to be stored in the soil during an irrigation day: this depends
on the time of beginning of irrigation, and the variation of the sap flow at each time of
the day. In this case, the maximum variation of water content in the zone humidified by
drippers was 105 l, for one tree, during one day, while the minimum was only 25 l. So,
with a good choice of the hour of beginning daily irrigation, some difficulties due to the
soil -for example, too high permeability-, can be avoided. Moreover, the water is then
always at a high availability level for the crop, excepting from 6 to 8 p.m., where the
cumulative balance of the day is negative; but this appears only during about 2 hours,
and when the climatic conditions are less hard, in the evening. This reasoning can be
adapted to many cases, and other examples are given. It can help the farmer to choose
in which order to irrigate his fields, when they have different soils. This method also
allows the limitation of deep percolation under the dripper.
67
Improving a Model for Predicting Peach Tree Evapotranspiration
R. Scott Johnson
UC Kearney Agricultural Center
9240 S. Riverbend Avenue
Parlier, CA 93648
Jim Ayars
Water Management Research Laboratory
USDA/ARS
9611 S. Riverbend Avenue
Parlier, CA 93648
Ted Hsiao
Land, Air & Water Resources
University of California, Davis
One Shields Avenue
Davis, CA 95616
Abstract
A model of young peach tree evapotranspiration (ET) was reported on
previously. It was developed using data from the first two years of growth of “Crimson
Lady” peaches planted in a large weighing lysimeter. Tree transpiration and soil
evaporation were modeled as separate components. The model predicts daily peach tree
ET based on reference crop ET (ETo) and several simple measurements from the
orchard. Since then, two more years of data have been collected and several
improvements to the model have been made. The model can now be used for mature as
well as young trees. Tree transpiration was originally modeled as a function of canopy
size as measured by light interception at solar noon. A vapor pressure deficit function
was added which explains some of the short-term variation observed in the lysimeter
trees. Percent canopy light interception of very small trees can be difficult to estimate
accurately. Therefore, equations were derived from measurements of tree height and
canopy spread, and were verified in the field. To improve the soil evaporation
component of the model, an equation was developed to estimate the percent of the
irrigation wetted area in full sun over the course of the day for different irrigation
systems and planting configurations. The model can now be applied to peach trees of
any age and spacing, and a range of irrigation regimes.
68
Implementation of Partial Rootzone Drying in shiraz winegrapes using
sub-surface irrigation
G. Kelley(1), G.S. Rogers(2), M. Collins(3), G. Cresswell(4), D. Hinton(5), E. W. R.
Barlow(3), S. A. Little(2), and J. P. Conroy(1).
(1) Centre for Horticulture and Plant Science, University of Western Sydney, Locked Bag
1797, Penrith, NSW 1797, Australia.
(2) AHR CropScience, PO Box 552, Sutherland, NSW, 2232, Australia.
(3) Food Production and Horticulture, University of Melbourne, Victoria, 3010
Australia.
(4) Cresswell Horticultural Services 119 Cabbage Tree Rd, Grose Vale, NSW, 2753,
Australia.
(5) BUI Technologies, 344 Annangrove Rd, Rouse Hill, NSW, 2155, Australia.
Abstract
Partial rootzone drying (PRD) was developed in Australia and has permitted
high-quality winegrapes to be grown using less water than required for conventional
production. The PRD technique is usually implemented using alternating drippers in
conventional above-ground drip irrigation. Especially in light textured soils, drippers
may wet only a small volume of soil, and water may be lost below the root zone.
Subsurface irrigation may alleviate these problems. Furthermore, by increasing the
volume of soil exploited by roots, plant nutrition may be improved and requirements
for fertilizer reduced. This study investigates the implementation of PRD using
subsurface capillary irrigation, which offers even greater potential savings in water for
winegrape production over PRD alone. Field experiments have been established at the
University of Western Sydney, Richmond, and on a commercial vineyard at Benalla,
Victoria to compare PRD implemented using both conventional drip irrigation and the
new subsurface capillary irrigation system known as Capillary Root Zone Irrigation
(CRZI). We measured root distribution and growth, soil water content, plant water
relations, plant growth, photosynthesis, plant nutrition and berry yield and quality.
Interpretation of the first two years’ results was complicated by difficult environmental
conditions, but initial results indicate that increased water savings may be possible
using subsurface irrigation to implement PRD. However, more work is required on
managing the soil wetting pattern to minimise plant water stress and it may be more
viable to implement subsurface irrigation when a vineyard is established, rather than
fitting it retrospectively.
69
Water Requirement and Water Use Efficiency of Fresh and Waiting-bed
Strawberry Plants
Kirschbaum, D.S., Larson, K.D., DeJong, T.M.
Department of Pomology, University of California Davis, One Shileds Avenue, Davis, CA
95616.
Correa, M., Borquez, A.M.
INTA Famaillá, Ruta Prov. 301, Km 32. (4132) Famaillá, Tucumán. Argentina
Abstract
Water requirement and water use efficiency (WUE) were determined for
commercial strawberries (Fragaria × ananassa Duch. ‘Chandler’) in Tucumán (INTAFamaillá, Argentina). In 1995, two kinds of plants were compared: fresh (F) and
waiting-bed (WB) plants. Water was applied to partially or fully compensate deficits
(D) in the hydrologic balance (HB=Precipitation-ET Penman), according to the
following schedules (treatments): 1- supply 50% of D 3-times/week, 2- supply 50% of D
5-times/week, 3- supply 50% of D daily, and 4- supply 100% of D. Treatment 4
produced the highest yield (3.3 kg.m-2) due to significantly increased fruit number and
fruit weight, while treatments under water stress (1, 2 and 3) produced between 2.4 and
2.5 kg.m-2. WB plants, compared to F plants, had higher yield (3.2 kg. m-2 versus 2.0
kg. m-2) and higher WUE, expressed in grams of fruit per liter of water received (5.2
g.L-1 versus 3.3 g.L-1). A highly significant interaction ‘WB x treatment 4’ was found in
terms of yield (4 kg.m-2). WUE was not statistically different among treatments and
ranged from 4.0 to 4.5 g.L-1, showing that water stress did not affect WUE. In 1997,
treatment 4 was adopted to irrigate F plants of ‘Chandler’ in other trials, producing 2.1
kg.m-2 and WUE=3.2 g.L-1, which reproduces the results obtained in 1995.
70
Water Use and Stomatal Behavior of Sweetgum (Liquidambar styraciflua)
relative to Reference Evapotranspiration in three Contrasting Regions
Roger Kjelgren, Dept. Plants, Soils, and Biometeorology, Utah State University
Richard Beeson, Dept. Horticulture, University of Florida;
Thayne Montague, Dept. of Plant and Soils Science, Texas Tech University
Abstract
We investigated water use of sweetgum cultivar (Liquidambar styraciflua
‘Moraine’) in three different regions of the US: semi arid (Logan, Utah), semi-humid
(Lubbock, Texas), and humid (Orlando Florida). Three individual field-grown, then
containerized, trees measuring approximately 80 mm in trunk diameter 300 mm above
the root crown were received at each site from a commercial nursery. These trees were
potted in to large containers with organic media. Tree water used was then measured
over the season at each with load cells connected to dataloggers, toploading at Logan
and Lubbock and hanging in Orlando, concurrent with measurement of ASCE
standardized reference evapotranspiration (ETo) from adjacent weather stations.
Trees were watered daily, and allowed to dry by irrigating at half of their well watered
use rate, and midday and morning conductance, as well as predawn water potential,
were measured. Dawn-to-dusk stomatal conductance was measured several times
during the season. At the end of the season total tree leaf area was collected and used to
normalize volumetric water use data to depth units. Preliminary analysis of the data
from Logan and Orlando shows that the depth of water loss ranged from 1-3 mm/day,
which was 30-50% of ETo, the lower values occurring at high ETo rates. Dawn-to-dusk
stomatal conductance exhibited closure in response to vapor pressure deficits of 1.5-2 at
Utah and Florida, levels that occurred by 9 am in Utah but not until noon in Florida.
Consequently, conductance values reached maximum 400 moles m-2 s-1 in Florida at
midday, while maximum values in Utah occurred within two hour of sunrise.
Stomatal conductance during the partially-irrigated dry down in Utah were nearly
unaffected at mid-morning, but afternoon values declined by 80% through the course of
the dry down. These partial results indicate that sweetgum water loss, and to a certain
extent growth, are limited in drier climates due to low-humidity induced stomatal
closure, and the resulting water use fractions relative to ETo may be somewhat lower.
71
Scheduling Automatic Irrigation by Threshold-set Soil Matric Potential
Increases Irrigation Efficiency While Minimizing Plant Stress
Isaac Klein, Institute of Horticulture, ARO, The Volcani Center, Bet Dagan 50250, Israel
Abstract
In the absence of a convenient and reliable plant water stress indicator which
can be used for automatic irrigation, the only rational solution today for scheduling
irrigation is to rely on soil matric potential (ψso) measurements. A modified tensiometer
(CommonSensor, patent pending) has been tested in the last two years for controlling
irrigation in soil-less, and soil planted culture. The CommonSensor logs the data of the
soil matric potential continuously (i.e. every several minutes), schedules the irrigation
automatically at a pre-set potential (0-50 kPa, i.e. –10, -20, -35 kPa), and control depth
of irrigation by closing the irrigation valve, using an appropriate allogarithm of time
(i.e. x1.5, x2.0, x2.5) required for the tension to decline to -5 kPa. The instrument is
battery operated, and logs 32.000 data points which can be readily downloaded, and
instantly parsed and plotted in an Excell spreadsheet. Opening and closing of the
irrigation valve is recorded and marked in the data sheet.
The CommonSensor improved the irrigation efficiency by reducing percolation,
avoiding irrigations under shifting environmental conditions when plant demand
declined temporarily, and by automatically adjusting over longer periods of time the
volume of irrigated water according to plant demand. Positioning of the
CommonSensor (distance and depth) in relation to the water source (dripper or
microsprinkler) needs to be adjusted to the soil mechanical properties to avoid
percolation. Under optimal positioning ψso could be kept close to the pre-set level.
The CommonSensor have been used successfully to schedule automatic
irrigation in potted (10-25 l) cherry, peach and fig plants bearing fruit in a screen house
and in drip irrigated grape and olive outdoors. Load cells connected to 21X Campbell
Scientific microloggers, using potted peach and fig plants, were used to monitor the
performance of the CommonSensor. In soil-less culture the CommonSensor scheduled
automatically the frequency (0-4 times/day), and timing of irrigation during the day,
according to the pre-set tension, the leaf area in relation to the potted volume, and
according to the environmental conditions. Efficient irrigation of grape and olive under
high water consumption in mid summer was at a daily frequency. When demand
declined (autumn-winter) frequency and water volume application was reduced
gradually. Stem water potential (ψst), photosynthesis (Pn), stomatal conductance (s) and
transpiration (E) of daily drip irrigated grape were highly correlated (r2 = 0.8833 –
1.000) in the morning hours to soil water tension (ca. 0 to – 27 kPa), as monitored by the
CommonSensor. At noon, when ψst declined to –10 atm, and after irrigation in the early
afternoon hours, ψso ceased to be correlated to Pn, s and E. Photosynthesis of potted fig
plants maintained between 0 and –10, -20 or –50 kPa declined from morning to the
afternoon hours, and it was inversely related (r2 = -0.9763 to -1.000) to ψso, measured
simultaneously.
72
Soil Water Dynamics in the Root Zone of a Micro-Sprinkler Irrigated
Almond Tree
Kouman S. Koumanov1, Jan W. Hopmans2, and Larry J. Schwankl2
1 Fruit Growing Institute, Plovdiv, Bulgaria
2 Dept of LAWR, University of California, Davis, U.S.A.
Keywords: root water uptake, microsprinkling, water balance, fruit trees.
Abstract
The spatial and temporal pattern of root water uptake in partially wetted soil,
was studied in the root zone of a six-year old micro-sprinkler irrigated almond tree. The
water balance of about one quarter of the root zone’s wetted soil volume (2.0 x 2.0 x
0.9m) was determined by neutron probe and tensiometer measurements. Soil water
content was measured at depths of 15, 30, 45, 60, 75, and 90cm using PVC neutron
probe access tubes, installed in a square grid of 50cm spacing to a depth of 120cm. Soil
water potential gradients at the bottom of the monitored soil volume were estimated by
eight pairs of tensiometers at depths of 82.5 and 97.5cm, installed in a regular pattern
between the access tubes. After linear interpolation of the tensiometer data across the
experimental plot, vertical water fluxes at the 90 cm soil depth were evaluated for all
access tubes locations. Neutron probe and tensiometer readings were taken at time
intervals of 4 to 24 hours. The rate of soil water depletion was calculated and used to
estimate the spatial and temporal distributions of root water uptake. Soil water
dynamics was studied in two stages: 1) during a week of conventional irrigation
management with three irrigation events; and 2) during a period of 16 days without
irrigation, after the monitored soil volume was thoroughly moistened so that soil water
was freely easily available everywhere, initially. The zones of maximum root water
uptake were the same for both stages in periods of high local rates of water application.
Hence, the almond tree appeared capable to redirect its root activity towards regions of
the most favorable water regime with mimimum soil water stress. After water
applications, root water uptake developed initially near the tree trunk, progressing
towards the periphery of the root system, shifting to root zone regions with minimum
soil water stress, thereby changing locations of maximum root water uptake.
73
Potential errors in long term measurment of sap flow using heat dissipation
probes
T. Lakatos
Research and Extension Centre for Fruit Growing
Vadastag 2, H-4244 Újfehértó
Hungary
Abstract
Measuring water consumption of trees seems to be sensitive tool for irrigation
scheduling. Heat dissipation method is one of the most wide-spread technique for the
measurement of sap flow in plant stems. The technique is relatively simple and
inexpensive therefore it is potentially suitable for using in the practice. In this study sap
flow velocity was measured by heat dissipation probes in two apple orchards on M.26
and M.9 rootstocks in five consecutive years at least 3 months per year. The trunk
diameter, foliage area and fruit load of selected trees differed in a wide range (30-90
mm, 3-25 m2, and 0-30 kg, respectively). Critical parameter of the heat dissipation
method is the maximum temperature difference (dTM) between heated and unheated
probes during times of zero flux. Deviation of actual temperature differece from dTM
as a baseline is used to estimate water flux. There were upto 100 % differences in
estimated tree water consumption using weekly, monthly or seasonally dTM to the sap
flow calculations. Daily dTM was related to some environmental and plant factor
(average daily temperature and trunk growth rate, respectively), and varied
significantly in most cases. However, daily sap flow velocity curves were close related to
calculated evapotraspiration curves or to other measures of plant water status (e.g.
trunk shrinkage) independently of the baseline position (weekly, monthly or seasonally
dTM). Heat dissipation probes in long term studies need regular calibration or
correction to the real water use estimation because of the uncertainty of the dTM
calculation.
74
The use of Microlysimeters for the ETM (Maximum Evapotranspireation)
measurement on tomato in greenhouse
M.G. Mameli, A. Sirigu, A. Soddu, F. Chessa, S. Meloni.
C. R. A. S. (Regional Centre for Agricultural Experimentation), viale Trieste 111, 09123
Cagliari, Italy. E-mail: [email protected]
Keywords: cv Camone, salinity, fruit quality, drip irrigation, fioroni.
Abstract
A trial was carried out for two years (2000, 2001 - 2002) in Sardinia (Italy),
where tomato is the most important greenhouse culture. Soil salinity and irrigation
water quality are the main causes of yield decrease on tomato production. However
quality parameters as berrys diameter, consistency and sapidity have improved, in
particular in the the local most important tomato variety (cv Camone).
The goal of the experiment was to verify the use of microlysimeters to measure
the ETM, as semplified in field metodology. ETM level have used in the equation
WR=ETM*Kd to determine the no water stress level (100%). Different level of induced
water stress, obtained with different percentage irrigation volumes reintegration, could
have influenced the yield quantity and quality parameters. The tomato cropping system
adopted was the long-cycle (October-June).
It has been adopted a randomized blocks design, considering the percentage of
irrigation water reintegration as variation source. The irrigation turn of the control
thesis (100%) has been defined when the 40% of AW (available water) have
evapotranspirated. Measurement with preassure chamber (Richards membrane) and
tensiometers datermined the soil water content.
During the first year they have been applied thesis 80%, 60% and 40%, while
the second year the thesis 50%, 25% and two thesis with different turns and lower
volumes has been adopted.
Preliminary results obtained have permitted to enlighten how irrigation
treatment have influenced the fruits yield parameters with significative increasing of its
quality on water stress plants. Irrigation has influenced all the biometric parameters
measured. Microlysimeters have been demontrated a reliable system of ET
measurement, but the level of real ETM was underestimated cause the development of
plants in pots.
75
Nutrition of Apple through Fertigation
Bruno Marangoni
Dipartimento di Colture Arboree,
Via G. Fanin, 46, 40127 Bologna
Italy
Abstract
Under field conditions we have compared the performances of apple trees
subjected to nitrogen (N), phosphorus (P), potassium (K) and magnesium (Mg)
fertilisation (80, 25, 100 and 12 kg/ha, respectively) applied to the soil surface by
granular fertilisers or given through the computer assisted drip irrigation system
(fertigation). The possibility of reducing fertiliser rates (by 50%) when they are applied
by fertigation as well as the need to apply P and K were also assessed. The apple
orchard, located in the Po Valley (Northern Italy), was planted in the winter 1996/1997
with trees of cv. Mondial Gala and cv. Fuji (strain Nagafu 6), both on EMLA 9, on a
fertile loamy soil. The experiment was arranged as a randomised block design with 5
replicates of 10 trees each. Data reported in this short paper refer to the 1999-2001
period. Treatments had only few effects of Fuji, where the highest rates of nutrients
caused excessive shoot growth. In both varieties fertigation (even at reduced rate)
proved to be more effective in providing K for tree uptake. Major effects were recorded
on Gala, where reducing nutrient supply by fertigation significantly reduced leaf N
concentration and shoot growth and slightly depressed fruit yields. Fruit colour in Gala
was lowest when nutrients were supplied to the soil surface in a granular form, it was
improved by fertigation and was maximum when nutrients were by supplied by
fertigation at reduced rate providing that K was included.
76
Long-term Effects of a Combined Deficit Irrigation Treatment on a Peach
Orchard Grown in a Deep Soil
Jordi Marsal, Marc Gelly, Mercè Mata, Amadeu Arbonès, Josep Rufat and Joan Girona.
Area Tecnologia Fruticola, Institut de Recerca i Tecnologies Agroalimentàries (IRTA),
Centre UdL-IRTA, Av. Rovira Roure, 177, E-25198 Lleida, Spain
E-mail: [email protected]
Abstract
During three consecutive years, a combined regulated deficit irrigation (RDISII-P) scheduling has been applied in a mid-maturing clingstone peach orchard located
in a semi-arid zone of northeast of Spain. By combining reductions in irrigation during
stage II of fruit development and postharvest, 30% less water on an annual basis was
applied when compared to a full irrigation requirement treatment (Control).
Comparing the results of this experiment to a precedent experiment carried out on
shallow soils it was observed that during the deficit period, irrigation can be more
restricted in deeper soils than in shallow soils. However, in deep soils the recovery in
tree water status is much delayed after full irrigation was resumed. Seasonal patterns in
fruit volume indicated significant less growth for RDI-SII-P than for Control fruits
during the deficit period (stage II) and the first part of Stage III. However fruit size
differences between irrigation treatments tipically disappeared during the last part of
stage III. At harvest, both tree water potential and fruit hydration ratio were
completely recovered. The effects of the RDI irrigation treatments on total yield were
neglegible and both fruit size and fruit count per tree remained unaffected. Tree size
and canopy intercepted radiation however, diminished progressively in RDI-SII-P trees.
This progressive reduction in tree size might raise some concerns about the
sustainability in the application of a combined RDI scheduling at longer-term than a
three-year period. On the other hand, RDI fruits at harvest had significantly higher
soluble solids than those of control. While water conservation is still the main interest in
Spain for applying RDI schedulings, RDI peaches could have a commercial advantage
provided some aspects of quality were considered for pricing fresh fruit production.
77
Response of Onion to Drip Irrigation
Don May
(Note: all correspondence concerning this paper proposal should be sent to
Blaine Hanson
Dept. of Land, Air and Water Resources (LAWR)
University of California, Davis
Davis, CA 95616 USA
Email: [email protected]
FAX: 530-752-5262
Abstract
The response of processing and fresh-market onion to drip irrigation was
investigated for conditions along the west side of the San Joaquin Valley of California.
Plot design was a latin square arrangement with irrigation amounts as the main
treatment and surface/subsurface drip irrigation as subplots for both processing and
fresh-market onion. Soil type was silt loam. Treatments were replicated five times.
Irrigation amounts were 120%, 105%, 90%, 75%, and 60% of a baseline amount. This
baseline amount was the product of reference crop evapotranspiration and a crop
coefficient obtained from a relationship between crop coefficient and canopy coverage
for furrow irrigation developed by Grattan, S.R., W. Bowers, A. Dong, R.L. Synder, J.
Carroll, and W. George ( New crop coefficients estimate water use of vegetables, row
crops. 1998. California Agriculture 52(1): 16-21). Measurements were crop yield and
soluble solids for processing onion, yield by size categories for fresh-market onion,
applied water, soil moisture content with a neutron moisture meter, canopy coverage
using a digital, infrared camera, plant height, and canopy temperature. A highly
significant linear response of both processing and total fresh-market onion yield to
irrigation amounts occurred for the range of amounts of applied water. This suggests
that the Grattan relationship is inadequate for drip irrigation under these site
conditions. For the fresh-market onion, a linear response of both colossal and jumbo
grades with applied water occurred. No yield response to applied water was found for
the medium grade. No differences were found between subsurface and surface drip
irrigation. However, it was found that onion yield increased with increasing amounts of
applied water, but canopy growth did not increase with applied water for the three
highest irrigation treatments. Maximum canopy coverage decreased with decreasing
applied water, however, maximum canopy coverage of the fresh-market onions was
more sensitive to applied water compared to processing onions. A trend of increasing
canopy temperature with decreasing applied water was found.
78
Fruit Size Monitoring as an Irrigation Scheduling Tool using Internal
Reference
Meron M*., Peres M.**, Rotman N.** and Assor, Z***
*MIGAL Galilee technology Center (corresponding author)
PO Box 831 Kiryat Shmona 11016, Israel, [email protected]
** Galil-Golan Extension Office, Min. of Agriculture, Israel
*** Northern R&D, Kiryat Shmona
Keywords: Phytomonitoring, Drip, Grapefruit, Crop coefficients
Abstract
Fruit growth responds strongly to plant water status, so monitoring fruit size is a
direct mean to achieve desired fruit dimensions by proper irrigation scheduling.
Deduction of irrigation needs from fruit volume changes is difficult because the
necessity to distinct between simultaneous responses to fruit load, heat stress,
atmospheric ET demand and soil water supply. Empirical base lines, simulation models,
and other external references currently lack the ability to do so. Using internal
reference made of differentially irrigated sub samples can provide the interpretation of
fruit growth rates for irrigation scheduling. In a field experiment at the Upper Galilee,
Israel, Grapefruit cv. "Star Ruby" was drip irrigated by hourly calculated, daylight
hours summed PET using crop coefficients derived from fruit growth rates. An
"internal reference" method was employed to distinguish fruit growth rates from
environmental and fruit load factors, by 30% over and 30% under irrigation. PET
coefficients were adjusted according to desired fruit size and the potential response to
change in irrigation, evaluated from the internal reference by an inference algorithm.
Fruit size was continuously monitored with electronic dendrometers and by weekly
manual sampling. Results show that the scheduling method was effective and enabled
fast response to climatic changes. The accuracy of the scheduling is primarily indicated
by the maximum marketable yield and economic return at the leading treatment, lower
yields and smaller fruit at reduced irrigation by 15% and 30%, and no gain in economic
returns at 30% increase in water.
79
Testing water potential in litchi trees as an indicator of water stress and its
effect on flowering intensity and yield
S.K.MITRA and D.Debnath
Department of Fruits and Orchard Management
Faculty of Horticulture
Bidhan Chandra Krishi Viswavidyalaya
Mohanpur 741252, Nadia, West Bengal,
India
Abstract
Low yield of litchi is a major problem worldwide. It is thought to be related to
poor flowering intensity. A dry period before flower differentiation is considered
beneficial to litchi flowering. To obtain a better understanding of the effects of soil
water deficits on flowering and yield of litchi, we studied the effects of water deficits on
water relation, carbon dioxide assimilation, growth and yield of field-grown 22 years
litchi cv.Bombai. We suggested that tree water status should not fall below a leaf water
potential in the morning of –1.3 MPa. This will be equivalent to watering every 10 to 12
days in sandy loam soil. The period of anthesis and early fruit development (fruit fresh
weight of < 1.0g) appears sensitive to drought. Water deficit decreased fresh weight of
flesh (20% lower in total fresh weight per fruit) than fruit from irrigated trees.
80
Establishing Reference values of Trunk Diameter Fluctuation and Stem
Water Potential for irrigation scheduling in the Olive
A. Moriana
E. Fereres
CMA “El Chaparrillo”
Agriculture Research Service
Junta de Castilla-La Mancha
IAS-CSIC and University of Cordoba
C d b S i
Keywords: Fruit load, LVDT, maximum daily shrinkage, Olea europaea, tree age, trunk
growth, water relations.
Abstract
Trunk diameter fluctuations (TDF) and stem water potential (SWP) were
recorded in well-irrigated olive trees with the aim of establishing reference values of
both indicators for irrigation scheduling. The measurements were performed in a
mature (18 years) and a young olive orchard (3 years) during 4 years. Two different
indicators derived from TDF: maximum daily shrinkage (MDS) and trunk growth
velocity (TGV) were evaluated. The annual relationship between MDS and vapor
pressure deficit (VPD) was hystheretic, probably caused by the presence of fruit as no
hystheresis was detected in ‘off’ trees. All data pooled gave an equation of
MDS=0.09+0.19VPD (R2=0.6). When only data until mid-August was used, the fit was
improved (R2=0.72; MDS=-0015+0.24VPD). Young trees had a slightly different
relationship with a steeper slope; MDS=-0.18+0.27VPD (R2=0.79). The relationships
between the SWP values and VPD were not as good as with MDS (R2 around 0.3), and
the regression slope was steeper in ‘on’ than in ‘off’ trees. TGV in the young orchard
had two maxima in the year; the first at mid-Spring (0.2 mm day-1) and the second at
the end of the summer (0.15 mm day-1). In the mature orchard, TGV had a single
maximum value, at the end of summer for ‘off’ trees, and in spring for ‘on’ trees.
81
Effectiveness of Over Tree Irrigation to Control Temperature Stress in sra
63 Clementines
Mulas M1., Fadda A1., Zurru R2. and Chessa G2.
1Dipartimento di Economia e Sistemi Arborei dell’Università di Sassari, Italy
2Consorzio Interprovinciale per la Frutticoltura di Cagliari, Nuoro e Oristano Italy
Abstract
In recent years, an increase in the marketing of Mandarin fruits was observed.
In particular, the production of high quality and seedless Clementines growing in
favourable areas obtains high economic results. This positive trend caused an increase
of cultivation to areas with less favourable climatic conditions, determining a decrease
in quality and quantity of yields. Moreover, the evolution of the irrigation systems from
over tree to under canopy distribution contributed to determine low qualitative
standard of the product. This market problem was especially observed in the
Mediterranean areas where high summer temperatures occur during fruit set. For this
reason a study was conducted to evaluate the effects of over tree irrigation on reducing
extreme climatic injury. The research was conducted in an experimental orchard and
replicated in a commercial orchard. Both sites are located in the South Sardinia (Italy)
where Citrus is frequently affected by heat stress. The effect of irrigation system was
determined comparing physiological behaviour of plants trated with both underground
and over tree irrigation. The physiological behaviour of the plants was evaluated
monitoring leaf chlorophyll content, leaf water potential, net photosynthesis, and leaf
temperature. Air temperature and relative humidity were measured inside the canopy
during the experiment. Results showed that over tree irrigation influenced the
microclimate inside the canopy affecting temperature and relative humidity of the air,
and leaf temperature. Photosynthetic activity showed a significant increased in
consequence of the reduction of leaf temperature.
82
Modifying Cotton Irrigation Management Practices in Response to Varied
Soil Characteristics
D.S. Munk, R. Hutmacher, B. Roberts, S. Wright and J. Wroble
University of California Cooperative Extension
Abstract
California’s San Joaquin Valley produces approximately 300,000 ha of cotton
annually including various cultivars of Pima, Gossypium barbadense, and Upland,
Gossypium hirsutum, cotton. San Joaquin Valley cotton water use estimates range
between 630 and 750 mm with surface irrigation systems dominant in the region that
require 3 to 10 irrigation events seasonally for optimum production. Irrigation
scheduling practices commonly incorporate soil moisture measurement information as
a primary or component means to schedule irrigation timing and volume. Cotton root
development patterns have historically been viewed to be relatively constant within an
individual cultivar only changing in time as the plant canopy develops. As part of a
larger study on water consumption habits of cotton, we monitored several cotton fields
having contrasting soil types and observed root development habit as well as soil water
extraction patterns that varied greatly as soil properties changed. Soils having either
very high or very low clay content were found to have the most limited root systems
with a need for more frequent and controlled irrigation events, while soils having more
moderate clay content expressed greater root development and slower plant stress
accumulation between irrigation events. Optimum irrigation scheduling for the region
is highly soil dependent with greater than a 3-fold difference in event scheduling time
based on field soil properties that influence root development and soil water
availability. These results support the argument that grower fields should be monitored
individually due to the dynamic nature of root growth rather than assuming a soil water
availability volume based on time of year or crop phenologic event. They also point out
the intrinsic benefits of plant-based measurements in determining optimum irrigation
schedules for cotton.
83
Comparative Evaluation of Pima and Upland Cotton Transpiration in the
San Joaquin Valley
D.S. Munk1, R.Snyder1, J. Robb2, R. Hutmacher1, and J. Wroble1
1
University of California Cooperative Extension and 2Westlands Water District
Abstract
The San Joaquin Valley produces upwards of 100,000 ha or 85 to 90 percent of
the U.S. Pima cotton, Gossypium barbadense, crop. This extra-long staple cotton is
prized for it’s high quality though it typically produces lower yields than Upland
cultivars, Gossypium hirsutum, adapted for most cotton producing regions of the world.
The active vegetative growth period of commonly grown Pima cultivars exceeds that of
Upland by 10 to 21 days, while a similar extension of the fruit maturity period has been
observed. We studied the extended vegetative growth periods of Pima cotton in
comparison to Upland cotton and made measurements to determine if this extended
growth period had any influence on seasonal crop water use patterns. During this
three-year study we made plant canopy measurements and used the surface renewal
approach to monitor crop evapotranspiration (ETc) throughout the growing season in
large-scale adjacent grower fields. While similar water management approaches were
employed between fields each year of the study, year-to-year differences in grower
water management practices appear to have influenced annual differences in ETc.
Increases in ETc were observed for Pima cotton both early and again late in the season,
however midseason water use estimates did not differ. The frequency and volume of
irrigation water applied was at least as important to seasonal crop water use, than
seasonal climate variation.
84
Practical Implications in Scheduling Irrigation of Deciduous Trees
Amos Naor
The Golan Research Institute
University of Haifa, Israel
Abstract
There are gaps between the scientific understandings of the factors affecting
irrigation scheduling of deciduous trees and the day-to-day irrigation scheduling of
commercial orchards in practice. Growers are able to account for the day-to-day
variations in evaporative demand by the use of daily potential evapotranspiration (ETp)
of a reference crop. In addition there are sets of crop coefficients – the ratio between the
evapotranspiration of a non-stressed crop and ETp, which reflects the dynamics of the
amount of light intercepted by the canopy and canopy conductance of a specific crop
along the season. Growers should pay attention to uncertainties in the evaluation of the
following site-specific parameters: Irrigation efficiency, which is affected by the
combination of soil type, soil depth, irrigation equipment and irrigation regime; Light
interception by the canopy, which may change with variety, rootstock, training system,
and with sub-optimal soil and climatic conditions; The degree of stress at a certain
phenological stage when experimental data is limited; The effect of crop level on tree
water consumption; The effect of crop load (a measure of the ability of the canopy to
support a certain crop level) on the threshold of water stress. The basic irrigation levels
should be adjusted empirically to account for the above-mentioned uncertainties using
water stress indicators. The sensitivity of a few water stress indicators to changes in
moisture availability and their inherent variability, as well as problems in setting a
threshold in a certain orchard will be discussed. A procedure for the assessment of the
relative water use efficiency between plots within an orchard will be presented. In this
procedure the average fruit size in each plot is plotted against the annual irrigation level
per a unit of yield weight, after the subtraction of the annual irrigation level below
which no commercial yield could be produced.
85
The effect of water stress applied alternately to half of the wetting zone
along the season (PRD) on wine quality, yield and water consumption of
red wine grapes.
*Naor, A., *Zehavi, T. *Gal, Y. and **B. Bravdo
*Golan Research Inst. ** The Hebrew University of Jerusalem, Rehovot POB12
Israel, 76100 [email protected]
Abstract
Three levels of irrigation regimes were applied during three successive years to a
6 year Merlot grafted onto 110R rootstock. The vineyard is located at the Kibbutz
Yiftakh commercial vineyard in the upper Galilee region of Israel at an elevation of
700m on a deep terra rossa soil. The three drip irrigation levels applied by drip
irrigation consisted of 0.15, 0.28, and 0.55 average seasonal class A pan evaporation
coefficient respectively. The seasonal accumulated water applied varied between 120 to
450mm, equivalent to 50, 100 and 200% respectively of the official recommendation for
wine grapes in this region. Each irrigation levels was applied by both one and 2 laterals
per row, the two lateral treatment was applied in a PRD mode, namely alternating the
irrigation between the two sides of the vines every two weeks whereas the one lateral
per row served as a control. The six treatments were applied in a 5 randomized block
design with 10 vines per replicate. The following measurements and analyses were
made: Crop level, pruning weight, crop load, number of clusters, berry number and
weight, Brix, TA, pH, stem water potential, stomatal conductance and CO2 uptake by
gas exchange. Soil water content and potential eas were measured by Neutron
scattering device. Wine was prepared from each replicates by minivunification. Sensory
evaluation by experienced panel as well as volatile GC-MS analyses were conducted.
Results of all measured parameters showed no significant effect of PRD. Significant
effects of the irrigation levels on many parameters were found along the three
experimental years. The results of this study contradict reports of other field
experiments, where proper control treatments were not implemented. A thorough
search of root physiology mechanisms leads to a conclusion that drip irrigation
principles are based on partial root drying and therefore alternating irrigation between
vines sides are not expected to have any advantage under field conditions. The
difference between short time split root container experiments under controlled
conditions and field experiments will be discussed.
86
Measurements of Sap Flow for Apple Trees in Relation to Climatic and
Watering Conditions
Z. Nasr and N. ben Mechlia
Institut National de la Recherche Agronomique de Tunisie
Rue Hedi Karay 2049 Ariana - TUNISIA
Keywords : Golden Delicious, deficit irrigation, Granier Technique, Transpiration, Kcb
Abstract
An experiment was conducted in an apple orchard located near Tunis in order to
determine the daily rates of sap flow of trees. The Golden Delicious cultivar planted on
rows oriented NW/SE at the density of 1250 trees/hectare was used. Measurements
concerned microclimatic factors and sap flow of two trees subjected to different
watering conditions. Hourly data showed certain sensitivity to the existing natural
thermal gradient in the morning. In spite of these difficulties, it was possible to observe
similarities between the daily course of sap flow and solar radiation although sap flow
remained more or less constant when radiation reached a threshold value of about 500
w/m2. However daily values were poorly correlated with radiation, vapor pressure
deficit and temperature. These measurements were used to obtain a quantitative
approximation of the basal crop coefficient Kcb over the entire growing season. Kcb
increased from 0.4 at flowering to reach a plateau 60 days later at cell division fruit
stage. Thereafter it remained constant at 0.75 for more 60 days before decreasing to 0.5
at ripening. For the tree conducted under deficit irrigation, sap flow values decreased
by 35% in comparison to the fully irrigated one. The slow down occurred at the end of
the season when water supply covered respectively 0.46 and 0.81 ETo for the
experimental trees.
87
Stem water status parameters and stem growth in the red pitaya
Hylocereus undatus
Avinoam Nerd and Peter Neumann
Division of Agricultural Engineering, Faculty of Civil and Environmental Engineering
Technion Israel Institute of Technology, Haifa 32000, Israel
Abstract
Hylocereus undatus is a vine cactus from central America that has recently been
established as a fruit crop (pitaya) in many tropical and subtropical countries. The
relationships between stem growth and stem relative water content (RWC) or stem
water potential (ψ) were studied in watered and droughted (irrigation withheld) potted
plants growing in a sandy soil under controlled environment conditions. Soil ψ
decreased from 0 to <-1.5 MPa during the first five days of drought. Growth of new
stems (emerging at the beginning of the study), RWC and ψ of mature stems decreased
from the second week in droughted plants. After 3 weeks RWC and ψ of mature stems
were 64% and –0.76 MPa in droughted plants versus 87% and –0.58 MPa in watered
plants. The drought related changes were less pronounced in young stems, RWC and ψ
were 83% and –0.43 MPa in droughted plants versus 88% and –0.35 MPa in watered
plants. Since ψ in young stems was always more positive than ψ in mature stems and
girdling the phloem at the base of new stems induced rapid decreases in growth we
propose that water is transported from the mature stems to the new stems via the
phloem. Phloem involvement in water supply to growing stems in H. undatus may
increase their resistance to growth inhibition by water stress.
88
Water and Land Productivity under Conventional versus Three
Dimensional (Vertical) Cultivation Technique
M.N.Nimah, K.C. Corbani, and I.Bashour
Faculty of Agricultural and Food Sciences
American University of Beirut, Lebanon
Keywords: Vertical cultivation, Water Productivity, Evapotranspiration, Crop yield, 3-D
technique
Abstract
Agricultural productivity and sustainability are of the most challenging cases
facing the world today with water and land being the limiting factors and increased
food demand being the urge. In order to meet the imposed challenges, a wise use of
these scarce agricultural resources must be considered. The objective of this research is
specially designed to serve the mentioned aim: increasing production by saving space,
water, and environment. To meet the above goal, an experiment was designed to
measure water and land productivity using a 3-D technique. This technique consisted of
vertical columns filled with soil where evaporation was prevented by covering the
column surface. Another treatment was to keep surface exposed and get the
evapotranspiration from the whole pipe. Those two treatments with each containing
different density of plantation/ pipe (1, 2, 3 and 4 plants) were compared with the
conventional way of plantation. Two crops, strawberry and beans were used in this
experiment and results showed a great difference in water and land use using the 3-D
technique.
In the strawberry experiment the highest water productivity was for the double
with a density of three plants/pipe compared to the control and the values were 17.25
kg/m2, and 3.62 kg/m2, respectively. As for the beans the highest water productivity
was for the double pipes with a density of one plant/pipe and the values were 9.93 kg/m2
and 1.09 kg/m2, respectively.
89
Stem water potential as a measure of water stress in north San Joaquin
Valley strawberries
Maxwell Norton, UC Cooperative Extension
2145 Wardrobe, Merced, CA 95340 and
Ken Shackel, UC Davis Pomology Department
Abstract
The pressure chamber was evaluated as a tool to measure plant water stress in
strawberries grown in the north San Joaquin Valley on sand under drip irrigation.
Timing studies showed that opaque, airtight bags only needed to be left on the
compound leaves for about thirty seconds before making reliable readings of mid-day
stem water potential (MDSWP). MDSWP taken over two years suggest that
strawberries grown under these conditions undergo water stress very quickly after
water is withheld. Values for different dates and for different sites were very similar
which suggests that strawberries grown under these conditions respond similarly.
When MDSWP readings were compared to nearby tensiometers set 30 cm deep, the
data suggested that 30 cm was too deep, and that 15 cm would have been more
indicative of root zone moisture levels. The MDSWP data followed closely the baseline
data for deciduous orchards in the region so it also appears that strawberries respond
to vapor pressure deficits (VPD) in a manner similar to other deciduous tree crops in
the region.
90
Post-harvest Irrigation management in an early ripening table grape
cultivar
Nuzzo V., Montanaro G., Dichio B.
Dipartimento di Produzione Vegetale
Universita’ degli Studi della Basilicata
Via N. Sauro, 85 – 85100 Potenza
ITALY
Abstract
This work shows the results of a three years trials on the effects of water
availability on a ‘Superior Seedless’ vineyard during the post-harvest period. The vines
were trained to ‘tendone’ system with a plant density of 800 vines per hectar, covered
with a plastic film to obtain an earlier ripening of the berries.
The vineyard water consumption was calculated using the Hargreaves equation
multiplied by an appropiate crop coefficient. Shoot leaf area evolution has been
determined by means destructive sampling. The following measurements were
performed on each shoot: number of stem leaves and lateral leaves, leaf area of stem
and lateral leaves, stem and lateral length. Further observations have regarded leaf
water potential and soil humidity. At pruning time, the number of shoots per vine, their
length and weight were measured separately on main and laterals axis.
The pre-harvest irrigation scheduling was set giving back each week all the ETc
of the period, while in the post-harvest phase two thesis, a ‘Control’ or ‘Irrigated’ one
and a ‘30% Irrigated’ one, where established. The criteria fixed in pre-harvest were
followed for the control. Concering the ‘30% Irrigated’ thesis it was decided to give
back 30% of the ETc of the period whenever 70% of the available water had been used
up in the first 60 cm of soil.
The results of the present work have pointed out that a moderated water stress
imposed during the in the post-harvest phase produced, in economical terms, about 100
mm of irrigation water saving on farm scale and also a smaller development of the leaf
area on the laterals axis and a greater length of strongly lignified main axis. This is
particularly important for the cultivar under discussion as it is characterized by basal
bud sterility and needs of long cane in order to guarantee high productive levels.
91
Pear water relations under partial rootzone drying
M.G. O'Connell and I. Goodwin
Department of Primary Industries
Private Bag 1, Tatura, Victoria 3616, Australia
Abstract
Partial rootzone drying (PRD) in a microjet irrigated pear orchard on a loam
soil in the Victorian Goulburn Valley, Australia was investigated during the 2002/03
season. The experiment examined the effects of PRD on soil water content, crop water
relation, vegetative growth, yield components and fruit quality. PRD treatments
included 50% (0.5PRD) and 100% (1.0PRD) of estimated crop water requirement
applied to one side of the tree on a 14-day alternating cycle compared to the control
treatment (1.0C), which received 100% of crop water requirement on both sides.
Irrigation was applied daily to replace reference crop evapotranspiration (ETo)
estimated using FAO mid-season crop coefficient for pear with adjustment for effective
canopy cover (ECC). ECC was measured by canopy PAR interception at solar noon
and remained at low levels (<30 %) during the season. ECC did not differ between
treatments. The crop response of the 1.0PRD treatment was similar to the control
(1.0C). The irrigated rootzone of all treatments was well-watered compared to the
drying profiles of the 0.5PRD and 1.0PRD treatments. Reduced fruit growth, decreased
stem water potential and increased leaf temperature under 0.5PRD indicate water
stress. These results indicate that 0.5PRD leads to significant water stress and no
evidence of the ‘PRD stomatal control mechanism’ as reported for grapevines (Dry and
Loveys 1999, Stoll 2000) was detected.
92
Monitoring soil moisture with Echo sensors in a citrus orchard under low
volume irrigation
N.V. O’Connell
University of California
Tulare County Cooperative Extension
4437 S. Laspina St. Ste. B
Tulare, California 93274
USA
R.L. Snyder
University of California
One Shields Avenue
Atmospheric Science
Davis, California 95616
USA
Abstract
A field experiment was established in a 35-year old navel orange orchard near
Lindsay, California to measure crop evapotranspiration with the surface renewal
method. As part of the experiment, dialectric aquameters (Echo probes from Decagon,
Inc.) were installed to monitor changes in soil moisture content during the irrigation
(April-October) and rainfall (October-April) seasons. The trees were planted at a
distance of 5.8 m in the row and 6.1 m between rows for a total of 46 trees per hectare
with the orchard floor maintained weed-free by means of herbicides. The trees were
irrigated using a low volume irrigation system with one mini-sprinkler per tree
delivering 38 liters per hour. The sprinkler rows are positioned on the south side of the
tree row with heads about halfway between the trees and near the drip line. The
sprinkler heads have a 360o pattern and throw water about 2.5 m. Echo soil moisture
sensors were installed vertically at 0 to 0.3 m and 0.3 m to 0.6 m depth at four locations
under the tree canopy near the surface renewal tower. The sensor locations were (1)
within 0.5 m of the sprinkler head, (2) halfway between the sprinkler head and the tree
trunk, (3) near the tree trunk, which is about 2.5 m from the head, (4) in the drip line on
the opposite side of the tree row. The measurements were recorded with a battery
powered data logger. In general, the sensors performed well. Because of the large
variation in water distribution pattern it was difficult to determine the absolute water
usage by the trees. However, because of the water extraction patterns, the sensors could
be used to help time irrigation.
93
Effect of Changes in Substrate Salinity on Stem Elongation
Oki, L.R., Lieth, J.H. and Kim, S.-H
Department of Environmental Horticulture
University of California, One Shields Avenue
Davis, California 95616-8587
email: [email protected]
Abstract
Stem elongation rates of Rosa hybrida L. ‘Kardinal’ stems were determined by
measuring changes in stem tip position using linear displacement position sensors
(LDPS) while plants were exposed to salinized nutrient solutions for 2 or 12 hours.
Greenhouse-grown plants were acclimated for at least 24 hours in a growth chamber
before treatment under constant 25oC and continuous light.
The plants were
automatically irrigated based on substrate moisture tension with half-strength modified
Hoagland’s nutrient solution (NS).
In the two-hour exposure experiment, plants were first irrigated with a
pretreatment application of NS at 1:00 am. The application of a treatment solution of
deionized water (DI), NS, or NS with NaCl to increase the solution electrical
conductivity (EC) by 1, 2, 4, or 8 dS m-1 (+1, +2, +4, and +8, respectively) was followed 2
hours later. A post-treatment irrigation with NS followed after 2 more hours.
The shoot elongation rate (SER) of plants treated with DI increased to 1.25 mm
-1
hr from 0.95 mm hr-1 and returned to the pretreatment rate after the final irrigation.
Treatment with NS, +1, +2, +4 had no effect on growth rate. However, the application
of the +8 treatments caused SERs to decrease from 1.08 to 0.22 mm hr-1. Following the
final leaching irrigation, shoot growth rates of salinized plants returned to or exceeded
pretreatment rates.
In another experiment, the treatment solution was not leached and data was
collected for 12 hours after the treatment. Application of the +2, +4, and +8 solutions
caused immediate reductions in SER. Growth rates then increased and restabilized
after 4 to 6 hours. Stems of the +2 and +4 treated plants recovered to the pretreatment
elongation rates, but +8 treated stems only partially recovered to 78% of the
pretreatment rate.
Changes in stem position of plants grown in a growth chamber were measured
for at least 24 hours under constant light and temperature. During this acclimation
period, the plants were automatically irrigated based on substrate moisture tension to
maintain constant water content. The plants were treated with salinized nutrient
solution for 2 or 12 hours.
94
Effects of Different levels of Water Application in Post-setting and Postveraison on Quality Grapes, Must and Wine on cv. Cabernet Sauvignon
César Acevedo Opazo1, Samuel Ortega-Farías1, Yerko Moreno Simunovic2
Centro de Investigación y Transferencia en Riego y Agroclimatología (CITRA).
Facultad de Ciencias Agrarias. Universidad de Talca. Casilla 747-Talca, Chile.
E-mail: [email protected]; [email protected]
2
Centro tecnológico de la vid y el vino (CTVV). Facultad de Ciencias Agrarias.
Universidad de Talca. Casilla 747-Talca, Chile. E-mail: [email protected]
Keywords: water stress, grape quality, quality must, quality wine, Cabernet sauvignon
Abstract
An experiment was carried out to evaluate the effects of diferent levels of water
application during post setting and post veraison on quality grapes, must and wine on a
vineyard, located in the Pencahue Valley, Maule Region of Chile (35º 22' LS; 71º 47'
LW), during the 2000-01 growing season. The cultivar was a 7 year-old Cabernet
sauvignon drip irrigated and trained to a vertical trellis system. Irrigation treatments
were the application of 40%, 70% and 100% of the vine evapotranspiration (ETvine)
during post setting and post veraison. The results showed that the best quality grapes,
must and wine was obtained by applying the 40% of the ETvine in post setting and 70%
of the ETvine in post veraison. On the contrary, the worst treatment was obtained with
a level of 100% of the ETvine during the whole period, showing a higher titartable
acidity and low total phenolics and anthocyanins on grapes and wine. On the other
hand, we observed that the treatment of 40% ETvine during post setting plus 70%
ETvine in post veraison determined an significant increment in the global quality and
wine sensory attributes.
95
Consumptive Use Calculations for Planning
M.N. Orang and S. Matyac
Calif. Dept. of Water Res. – Div. of Plan. &
Local Assist, Sacramento, CA, USA
R.L. Snyder
Department of Land, Air and Water
Resources, Davis, CA, USA
Abstract
The California Department of Water Resources (DWR) and the University of
California (UC) have developed a user-friendly Excel application program (CUP) to
improve the dissemination of Kc and crop evapotranspiration (ETc) information to
California growers and water purveyors. CUP computes reference evapotranspiration
(ETo) from monthly means of solar radiation, maximum, minimum temperature, dew
point temperature and wind speed using the 24-hour Penman-Monteith equation for
short canopies. The program uses a curve fitting technique to estimate daily ETo and
rainfall from the monthly data. Bare soil evaporation is estimated as a function of ETo
and rainfall frequency. A bare soil Kc value is calculated to estimate the off-season
evapotranspiration and as a baseline for in-season Kc calculations. In addition, CUP
adjusts row crop initial growth Kc values for irrigation frequency and it accounts for
the influence of orchard cover crops on Kc values. In addition, the latest crop
coefficients are provided in a flexible format to permit easy updating. The application
outputs a wide range of tables and charts that are useful for irrigation planning. Design
features of the CUP application will be discussed.
Deficit Irrigation Strategies using Midday Stem Water Potential in
Winegrape
S. O. Ortega-Farias and C. Acevedo
Centro de Investigación y Transferencia en
Riego y Agroclimatoligía (CITRA), Facultad
de Ciencia Agrarias, Universidad de Talca.
Casilla 747-Talca, Chile.
E-mail = [email protected]
1
M. Duarte and Y. Moreno
Centro Tecnológico de la Vid y el Vino
(CTVV), Facultad de Ciencia Agrarias,
Universidad de Talca. Casilla 747-Talca,
Chile.
E-mail = [email protected]
2
Abstract
An experiment was carried out to study deficit irrigation strategies using midday
stem water potential on a vineyard, located in the Pencahue Valley, Maule Region of
Chile (35º 22' LS; 71º 47' LW), during the growing seasons 2001-2002 and 2002-2003.
The cultivar was a 8 year-old Cabernet sauvignon irrigated by drip irrigation and
trained in a simple trellis. The irrigation treatments were the application of 40%, 70%
and 100% of the vine evapotranspiration (ETvine) during post setting and post
veraison. The results showed that the better combination of quality of grape, yield and
vegetative balance was obtained by using values of stem water potential ranging from –
1.0 to –1.3 MPa during post-setting and from –0.75 to –1.1 during post-veraison. In this
case, the water application was 40% and 70 % of the ETvine during post-setting and
post-veraison, respectively.
96
Talca Irrigation Mangement System for Winegrape
S. O. Ortega-Farías , C. Acevedo, A. Acevedo and B. Leyton
Centro de Investigación y Transferencia en Riego y Agroclimatoligía (CITRA)
Facultad de Ciencia Agrarias, Universidad de Talca. Casilla 747-Talca, Chile.
E-mail = [email protected]
Abstract
As a result of increasing pressure on water resources available for irrigation in
Chile, grape-growers have widely adopted drip irrigation as a means to efficiently apply
sometimes very limited quantities, and in some instances moderately irrigation water.
The widespread interest in irrigation management has also been stimulated by a
growing demand for fruit of higher quality, which is cost competitive for the rapidly
expanding Chilean wine export market. Thus, CITRA used the a network of automatic
weather stations in combination with measurements of soil moisture content to provide
farmers with the information required to control the turn-on and turn-off decisions in
irrigation scheduling of commercial vineyards under drip irrigation. The results of the
irrigation service in the Maule Region suggested that is possible to increase overall
water use efficiency from 5 to 9 kg m-3 and enable grape-growers to use deficit
irrigation strategies to increase grape quality.
Evaluation of the FAO Penman-Monteith Method to Estimate Reference
Evapotranspiration in the VII of Chile1.
S. O. Ortega-Farias and Victor Rojas
Centro de Investigación y Transferencia en Riego y Agroclimatología (CITRA)
Depto de Facultad de Ciencia Agrarias, Universidad de Talca.
Casilla 747-Talca, Chile. E-mail = [email protected]
Abstract
A study was carry out in order evaluate the FAO Penman-Montieth (FAO-PM)
model to compute reference evapotranspiration (ETr) over a well irrigated grass
canopy at the Panguilemo Experimental Station (PES), which is located in Talca, Maule
Region of Chile. An automatic weather station and Bowen ratio system were installed
in the central part of the grass canopy to measure climatic variables and energy balance
components. On hourly basis, results indicated that FAO-PM model was able to predict
ETr with a standard error of estimate (SEE) of 0.07 mm h-1 and an absolute error (Ea)
of 8 %. Major disagreements were associated with an overestimation of the net
radiation.
1
Investigación financiada por el proyecto FONDECYT N° 1970309
97
Measurement and Estimate of Peach Orchard Evapotranspiration in
Mediterranean Conditions
T.A. Paço, N. Conceição and M.I. Ferreira
Instituto Superior de Agronomia
Universidade Técnica de Lisboa
Tapada da Ajuda, 1349-017 Lisboa, Portugal
Abstract
Ecosystems of Mediterranean type have particular characteristics that imprint a
distinct behaviour in the use of resources, as it is with water use and crop exploitation.
In this region, orchards have often to be regarded as sparse crops, even if they are
considered, in an economic point of view, as intensive agriculture. The
evapotranspiration of a peach orchard (plantation distance 5x2 m and crop ground
cover 29%) was studied, in central Portugal, during two irrigation seasons. ET was
directly measured with the eddy covariance technique, while simultaneous
measurements of sap flow (heat dissipation Granier method) and of soil evaporation
(microlysimeters) were also performed. The sap flow sensors provided recordings that
were upscaled to the stand level and showed an underestimation for transpiration.
These results, combined with soil evaporation were compared to eddy covariance
measurements and the relationship obtained was used for long term estimates of ET.
This approach allows the use of the continuous records of sap flow to estimate ET, for
the whole season, with a low cost and good reliability. Mean measured
evapotranspiration was about 2 mm/day, mean measured soil evaporation was around
10% of ET and mean measured crop coefficient was close to 0.5, for the considered
periods. Mean measured crop coefficients were lower than crop coefficients obtained
with the FAO approach (Allen et al., 1998) which yielded ET mean estimates over 30%
higher than the measured ET. At the farm level, irrigation efficiency was found to be
lower than expected for a drip irrigation system (from 50 to 70%).
98
Irrigation Water Requirements for some Horticultural Crops Specific to
the Dobrogea Region, Romania
*Cr. Paltineanu
Research Institute for Fruit Growing
0312 Pitesti-Maracineni, Romania
I.F.Mihailescu
Ovidius University,
8700 Constanta, Romania
Keywords: peach and apricot tree, table and wine grapes
Abstract
The actual trend in climate evolution emphasized the aridization risk that was
also observed in Romania, especially in its driest regions, e.g. Dobrogea, where most of
the crops had to be irrigated. This paper revealed the Penman-Monteith (PM) reference
evapotranspiration (ETo) values, estimates of crop coefficients (Kc) using the method
developed by Allen et al. (1998, FAO Irrigation and Drainage Paper 56), optimum crop
evapotranspiration as well as irrigation water requirements (IWRs) of some fruit trees
and grapes for a 38 year period, within 17 locations within the Dobrogea region,
Romania. Kc showed similar monthly values regardless of location, climate, soil and
relief within the region; in addition to crop growth stage PM-ETo was the main climatic
parameter determining a difference in crop evapotranspiration. Estimated Kc values
were compared to real Kc values obtained in field experiments under irrigation
conditions. A strong, highly significant correlation between these two parameters for
shorter periods was obtained, but crop evapotranspiration estimated by this method
was a little lower than real crop evapotranspiration previously reported for crops tested
in this area. This could rather be attributed to the lack of accuracy generated by
inaccurate measurements of deep drainage and runoff in experiments formerly
developed than to the deficiency of Allen’s method. In general, the highest ETo values
were registered in the south-western part while the lowest ones were met in the northwestern part of the territory studied. Similar to Kc, ETc presented minimum values in
spring when water evaporation from soils prevailed and in autumn as well, except for
wheat and barley. Maximum ETc values were recorded again in the south-western part
of the area, and in time in July when crop transpiration became also high and
dominated upon soil evaporation, and also when Kc was almost always higher than 1,
except for trees without an active groundcover and grapes. The highest IWRs in
Dobrogea occurred along its eastern coast, mainly due to the large precipitation deficit
in the area, whereas the lowest values were met within the north-western part of the
region. For the peak months IWRs of the fruit trees and grapes studied here were
interpolated using the kriging method, resulting in relatively homogeneous crop IWRs
areas. This resulted in drawing of relatively homogeneous optimum crop
evapotranspiration and irrigation water requirements areas. This paper brought
information on the spatial ETc and IWRs distribution over the Dobrogea region. At the
same time, the present paper confirmed the method recently developed by Allen et al.
(1998), in estimating Kc for any dry region or watershed in this country. This
achievement could also contribute to a better water management in this semi-arid
region that also had high water consumers.
99
Economic Optimization of Drip/Micro Irrigation Systems for Orange
Crops in Humid Regions
Alejandro Pannunzio and Alejandro Wölfle
Cátedra de Riego y Drenaje - Facultad de Agronomía –
Universidad de Buenos Aires
Ugarteche 3107 4ª -(C1425EVG)
Buenos Aires, Argentina [email protected]
Abstract
The economic profitability of three drip / trickle irrigation methods, were
compared using partial budgeting analysis. The experiment was conducted in an area,
north of Buenos Aires province, with 950 mm average rainfall during the last 16 years,
with a peak of 1362 mm in 1990 and a minimum of 593 mm in 1996. The crop is a
Washington Navel orange (Citrus Sinensis L. Obseck) on sour orange rootstock.
Rainfalls are well distributed during the year, so irrigation is supplementary. The drip,
microjet and minisprinkler irrigation system tested, wet 27, 59 and 110 % of the
shaded area by the crop. Annual ownership costs of irrigation systems were calculated
amortizing the system cost over its estimated useful life of 15 years. Due microirrigation
systems require annual replacement of some components, systems costs were estimated
in two categories, initial cost per ha and annual component cost per ha. Annual incomes
were calculated, by considering the net income to the grower, focusing in the export
prices, due the main scope of this crops are the fresh fruit, European markets. We
classified the production of each treatment, in categories, according with market
requirements, obtaining the gross income for each case. Even though the initial and
maintenance cost of minisprinkler systems, are higher than microjet and drip, the net
economic result, in case studied, is better for microsprinkler, due the higher yields, and
concentration of fruits in the better paid categories.
100
The Water need of Asparagus (Asparagus officinalis L.) determined in a
Lysimeter Station
P.-J. Paschold, B. Artelt
Department of Vegetable Crops,
Forschungsanstalt, 65366 Geisenheim, Germany
E-Mail: [email protected]
Abstract
Asparagus is the largest vegetable crop by area in Germany. About 18,000 ha
were grown in 2002, mostly with irrigation. Therefore, information is needed about the
need of water of the asparagus plants, and about how to reduce the environmental
pollution of the groundwater by nutrients.
A trial was carried out in a weighting lysimeter station to determine the
influence of different amounts of water on the development of asparagus plants. One
year-crowns of Netherlands cultivar Grolim were planted in April 1999 on a sandy soil
in weighting lysimeters. Three irrigation treatments were tested: 1. natural
precipitation without irrigation, 2. irrigation started if water content in the soil was
reduced to 70 %, 3. irrigation started if water content was reduced to 40 % of available
water content. Soil water content was measured with Time-domain reflectometry
(TDR) hourly. The plant development was measured during one vegetation period:
fern-high and stem diameter four times in summer and autumn. At the end of
November the trail was finished with the determination of the whole root biomass and
their distribution in the deep, their dry mass and the content of N, P, K, Mg, Ca. Weight
of all ferns and the number of ferns with stem diameter less than 10 mm increased
significantly by water amounts between 180 and 360 mm. The root biomass increased
significantly, too. The dry mass content and the content of the measured nutrients were
not significantly influenced. The distribution of the nutrients along the roots, measured
each 10 cm, has also not changed.
101
Irrigas - A New Simple Soil Moisture Sensor for Irrigation Scheduling
P.-J. Paschold
Department of Vegetable Crops,
Forschungsanstalt, 65366 Geisenheim,
Germany
E-Mail: [email protected]
A. Mohammed
Jimma University
College of Agriculture
P.o.Box 307.
Jimma, Ethiopia
[email protected]
Abstract
There are many different methods of irrigation scheduling, but often they are
difficult and expensive. The new soil moisture sensor Irrigas developed at Embrapa
Vegetables national research center (Brazil) as an irrigation controlling system has been
put into efficiency test in the Research Institute Geisenheim. Based on the results
obtained from two preliminary observations the new irrigation controlling system is
considered as simple, cheap and effective. Irrigas indicated the need for starting
irrigation between -200 and -300hPa, measured by tensiometer.
Irrigas is an easy method of determining the irrigation day in open fields, even
for farmers who has problems with read and write. The price is relatively cheap, the
device can be a promising irrigation-scheduling tool also for poor and illiterate farmers
in undeveloped countries. For commercial purpose, where crop plants at different
stages of development require different amounts and frequencies of irrigation, the
question of an apparatus with automatic and semi-automatic manoeuvrings is worth
considering.
Tomato plants, which were grown on plots under irrigation scheduled with
Tensiometer or Irrigas, had similar height, leaf, flower and fruit number.
102
Water Use Efficiency and Yield of Mango Trees in Response to Reduced
Irrigation
F.M.G. Vanassche
Department of Soil Science, University of the
North, Sovenga 0727
SOUTH AFRICA
E.W. Pavel
Dept. of Plant Production and Soil Science,
University of Pretoria, Pretoria 0002
South Africa
Abstract
Six-year-old ‘Kent’ mango (Mangifera indica L.) trees were subjected to five
irrigation regimes: control (Co, about 100% of field capacity), two progressively
reduced (PRI-1 and PRI-2, were irrigated up to about 80 and 70%, respectively, of field
capacity), a regulated deficit irrigation treatment (RDI, was irrigated like Co except for
water was withheld/reduced for 2-4 weeks during the last stage of fruit growth), and a
farm control (Co-F, commercial practices). Before flowering irrigation water was
reduced in all treatments for a period of 4-6 weeks. Trees were irrigated using a microjet system. Irrigation was scheduled in the four treatments (Co, PRI-1, PRI-2, and RDI)
according to daily neutron probe measurements, while the farm used tensiometers.
During the season of 2002-2003, water savings in the range of 15-62% were obtained in
the four irrigation treatments compared to the farm control. The five irrigation
treatments were evaluated with respect to yield and water use efficiency.
Evapotranspiration: Measuring and Modeling
Kyaw Tha Paw U
Department of Land, Air and Water Resources.
University of California, Davis
Abstract
Evapotranspiration (ET) is a key component of the hydrological budget. Direct
ET measurements are difficult, except by residual hydrological balance, lysimetry or
micrometeorological methods (which require extensive fetch). Other estimation
methods are actually simple models, such as using reference ET estimates and then
adjusting to actual ET using crop or ecosystem coefficients. Thornthwaite, Penman,
and Penman-Monteith reference ET estimates require meteorological data, and in
addition a crop coefficient. Energy budget residuals based on eddy-covariance, surface
renewal, and scintillometry are some of the more complicated, indirect or inferential
methods. More complicated models range from bulk transfer paradigms to advanced
higher-order closure or Lagrangian descriptions of turbulent exchange. These methods
are discussed, including the advantages and limitations expected for each method.
Recommendations are given on some cutting edge as well as conventional methods.
103
Vegetative growth and salt accumulation of six olive cultivars under salt
stress
S. Perica, M. Brkljača and S. Goreta
Institute for Adriatic Crops
Put Duilova 11, 21000 Split, Croatia
D. Romić and M. Romić
Faculty of Agriculture, Svetošimunska 25
Zagreb, Croatia
Keywords: Salinity, shoot, sodium, Olea europea
Abstract
The olive is one of the most widely cultivated fruit trees in Croatia, particularly
in its Mediterranean part – Dalmatia. An average yield of less than 10 kg/tree is
considered very low and is mostly attributed to summer draught. The coast and
particularly the islands suffer from scarcity of quality water sources. On the other hand
underground to some extent saline water is frequently available, which however has not
been used for irrigation so far. The olive is considered intermediate tolerant to salinity,
and more tolerant than other fruit trees. Therefore, the aim of this project was to screen
the most widespread autochthonous olive cultivars to different levels of salinity. Five
self rooted Croatian autochthonous olive cultivars (Buža, Drobnica, Istarska bjelica,
Lastovka and Oblica) and one Italian (Leccino) were grown in 1:1 quartz sand : perlite
substrate in a greenhouse. The plants were irrigated twice a day with 1/4 Hoagland
solution and subjected to 0, 33, 66 and 100 mM NaCl for seventy days. Some cultivars
started to show the effects of salinity as early as 10 days after the application. After 50
days of salinity exposure, all the cultivars showed reduced shoot extension at high
salinity conditions, best marked at 100 mM NaCl level. At the end of experiment the
shoot growth was reduced most at Buža, Leccino, and Lastovka, where the new shoot
length at 100 mM was 21, 36 and 37% of the growth obtained in control plants,
respectively. Under the same treatment, cv. Oblica had significantly better shoot
extension, 54 % of the control plants growth. Equally, Oblica showed the lowest level of
sodium accumulated in the leaves. Most of the cultivars differed significantly in terms of
the number of nodes and leaves only at the highest NaCl treatment.
104
Evapotranspiration of Bell Pepper in the Tropics as measured by a
Weighing Lysimeter
Reinaldo Pire
Posgrado de Horticultura. Decanato de
Agronomía. Universidad Centroccidental
Lisandro Alvarado. Apartado 400.
Barquisimeto. Venezuela. e-mail:
[email protected]
Rafael J. Rodríguez
Dpto. de Ingeniería Agrícola. Decanato de
Agronomía. Universidad Centroccidental
Lisandro Alvarado. Apartado 400.
Barquisimeto. Venezuela
Abstract
The knowledge of daily crop evapotranspiration may allow the grower to apply
the correct amount of irrigation water. However, in the tropics, the information about
the crop water consumption on a daily basis is scarce. In this experiment, the actual
evapotranspiration during the whole growth cycle of bell pepper (Capsicum annuum
L.) cv. Defiance, was measured. A precision weighing lysimeter (2.4 m2 area, 80 cm
deep, and 5 ton capacity) was installed in a sandy loam soil at the experimental field of
the Universidad Centroccidental L.A. at Barquisimeto, Venezuela (9º50’ N, 500 meters
a.s.l.) and twelve drip irrigated bell pepper plants grown on it. The lysimeter was
surrounded by an area of the same crop and a field of low, natural vegetation. The
results enable the precise estimation of the actual irrigation requirements of the crop,
thus favoring a more efficient water use, especially with irrigation systems, such as drip
or micro sprinkling, that allow frequent adjustments of the water volume applied.
105
Effects of recycled water on soil salinity levels of cool season vegetables
M.D. Cahn
University of California, Cooperative
Extension, Monterey Co.
1432 Abbott St. Salinas, CA 93901
USA
B.E. Platts
Dole Fresh Vegetables Inc.
PO Box 1759
Salinas, CA 93902
USA
R.B. Holden, and M.G. Malanka
Monterey Regional Water Pollution Control Agency
5 Harris Court, Bldg. D, Monterey, CA 93940
USA
Abstract
Agriculture in Monterey County, California is more than a $3 billion per year
industry. Over-pumping of ground water has caused sea water to intrude into wells
located near the coast. In an effort to reduce ground water extraction in the northern
Salinas Valley, the Monterey Regional Water Pollution Control Agency in partnership
with the Monterey County Water Resources Agency began providing recycled water to
4,900 hectares of prime farm land used to grow cool season vegetables in April 1998.
The dominant soil types in this region are clay loam and heavy clay soils, both of which
are susceptible to sodium accumulation and water penetration problems. Recycled
water, blended with well water, is used to irrigate artichokes, broccoli, Brussels sprouts,
celery, cauliflower, lettuce, and strawberries. Because of grower concerns that salts,
particularly Na and Cl, in the recycled water would reduce yield and quality of their
crops a long term study was developed to monitor salinity levels in commercial
vegetable fields. Soil salinity levels were monitored at 4 control and test sites beginning
in the spring of 2000. The control sites received well water and the adjacent test sites
received an approximate 2:1 blend of recycled and well water. Control and test sites
were paired so that they could be compared under the same soil, crop, drainage systems
and farming practices. The soil was sampled three times per year from all sites: spring
(before planting), mid-summer, and late fall. Composites of 4 cores were collected from
the 0 to 90-cm depth at 30-cm intervals. Soil samples were analyzed for pH, electrical
conductivity (ECe), extractable cations (B, Ca, Mg, Na, and K) and extractable anions
(Cl, NO3, and SO4). After 3 years of monitoring, the data showed that using recycled
water for vegetable production increased ECe (saturated paste extract) of the soil
profile from 2.0 to 2.9 dS/m but decreased the sodium adsorption ratio (SAR) from 2.9
to 2.6. The SAR and EC of soil samples from all sites were in a range acceptable for
vegetable production.
106
Fertigation Studies in Hybrid Watermelon in Semiarid Tropical Region of
India
M. Prabhakar and S.S. Hebbar
Division of Vegetable Crops
Indian institute of Horticultural Research
Bangalore 560 089, India
Keywords: Drip irrigation, polyethylene mulch, pan-evaporation, water soluble
fertilizers, fruit yield
Abstract
Water melon [Citrullus lanatus (Thunb.) Matsum. & Nakai] was grown in a drip
fertigation experiment on red sandy loam soil with and without black polyethylene
mulch under semiarid condition of South India. Total seasons recommended fertilizers
of 100 kg/ha each of Nitrogen, Phosphorous and Potassium were fertigated 100 per cent
or 50 per cent in combinations of NK or NPK using traditional fertilizer or water
soluble specialty fertilizers. These were compared with traditional fertilizers applied to
the soil. For fertigation treatments the required quantity and kind of fertilizers
Nutrient were injected weekly into the Drip Irrigation System. Irrigations were
scheduled based on Pan-Evaporation data to apply a volume of water equal to 0.7
times pan-evaporation losses throughout the growing season. Fruit yield with
polyethylene mulch was significantly higher (50.1 tons/ha) than with no mulch (42.8
tons/ha) . Fruit production was further increased by different combination of
fertigations as compared to soil application, with highest yield being observed with
entire quantity of NPK fertilizers supplied through drip irrigation water. Reduction in
fruit yields were noticed when fertilizers were applied in combination of soil and
fertigation mode, however quality parameters such as TSS and rind thickness were not
significantly influenced by any of these treatment combinations.
107
Influence of Fruit Load on the Water Relations of Olive Trees under
Different Growing Conditions
M.H. Prieto
SIDT. Consejería de Agricultura y Medio
Ambiente. Junta de Extremadura. Finca La
Orden. 06187. Guadajira (Badajoz). Spain.
A. Moriana
CMA “El Chaparrillo”Agriculture Research
Service. Junta de Castilla-La Mancha.
Ciudad Real, Spain
E. Fereres
IAS-CSIC and University of Cordoba.
Cordoba, Spain
Keywords: Midday Stem Water Potential, Crop load, Stomatal Conductance, Olea europaea,
water stress.
Abstract
The influence of fruit load on the water relations of olive trees was studied in two
orchards, located in Córdoba and Badajoz, under different growing conditions
including differences in water regime. In both locations, under all the irrigation
treatments, trees with a heavy crop load (“on”) had lower Midday Stem Water
Potential (SWP) than trees without a normal crop (“off”), from fruit set to harvest.
However the difference in stomatal conductance (gl) between “on” and “off” trees was
not as clear and it depended on the phenological stage; in Córdoba, gl was similar in
both treatments until day 240, after which it had higher values for“on” trees. In
Badajoz “on” trees always had higher gl than “off “tress. The stress level and rate of
stress development influenced tree response, mainly the gl; fast and severe water stress
reduce gl to the same low level in “on” and “off” trees. Differences in water status
among trees subjected to different levels of water deficits were more evident in “on”
trees, probably due to their higher conductance and transpiration rates.
108
Water Use Efficiency of Grapevines (Chardonnay) Subjected to Partial
Rootzone Drying and Deficit Irrigation
S. Pudney
South Australian Research and Development
Institute
Plant Research Centre, Waite Research
Precinct
Adelaide, South Australia
M.G. McCarthy
South Australian Research and Development
Institute
Nuriootpa Research Centre
Nuriootpa, South Australia
Abstract
A major constraint to the continued development of the Australian wine grape
industry is the availability of water. If vineyard expansion continues to meet forecast
expectations, the amount of water available for producing wine grapes will become
insufficient. At least part of the shortfall will need to be met through improvements in
vineyard practices. The objective of this study was to determine the most sustainable
irrigation method for Barossa Valley vineyards. The three year trial was conducted on
mature planting of Chardonnay. Five irrigation treatments were established: Full (F),
Full Partial Rootzone Drying (FPRD), Split (S), Deficit (D) and Deficit Partial Rootzone
Drying (DPRD). Soil moisture sensors were installed to calculate the water requirement
of the Full treatments. Deficit treatments automatically received half the amount of
water applied to the Full treatments. Split received the same amount of water as Full,
however the water was applied through two drippers (rather than one). Soil moisture
records and leaf gas exchange measurements confirmed that Partial Rootzone Drying
was implemented where intended. Yield was more closely related to the amount of
water applied than the method of application. Full treatments (F and FPRD) produced
more fruit than Deficit (D and DPRD). The yield from S was not significantly different
from any of the other treatments. Water Use Efficiency (weight of fruit produced per
unit water applied) was highest for Deficit and lowest for the Full irrigation treatments.
The improvement in water use efficiency was due to a reduction in the amount of water
applied, not the implementation of PRD. The results of this study suggest, that in some
vineyards, it may not be necessary to adapt irrigation systems for PRD in order to
achieve large improvements in Water Use Efficiency; the same may be achieved
through closely monitored deficit irrigation.
109
Use of Agrometeorological Data to Calculate Irrigation Requirment for
Potato
K.M. Refaee and Medany, M.A.
The Central Lab. For Agricultural Climate, 6
Alnoor st., DOKKI 12411. P.o.Box 296
IMBABA.Giza.
A.F.Abou-Hadid
Department of Horticulture, Faculty of
Agriculture, Ain-Shams Univ., Hadayek
Shobra 11241, PO.Box 68, Cairo, Egypt.
Abstract
IRRI_CLAC is a software developed by the Central Laboratory for Agricultural
Climate (CLAC) aiming at calculating daily irrigation requirement and irrigation
interval for a given growing season of potato. The software is divided into mean major
screen under it six details screens may be retrieve . The mean Screen includes two
sections; The first section reflects the required input data about varity, plant age, root
depth, potential evapotranspiration (ETo), depletion level, irrigation efficiency,
irrigation system, leaching requirement, and soil type. In addition to six buttons
covering the six required input data, the function of these buttons is to calculate the
required input data based to plant age. The Scand section reflects the output data of
irrigation requirement (m3/f), intervals (day) and duration (hour). The potential
evapotranspiration (ETo) may be calculate using following on of the two sources :Historical data related to the location and the farm area
Last year data related to the nearest weather station
In case of a viability of real data, (ETo) can be calculated using of on the
following four different equation according to the availability of weather parameters
1- Penman monteith
2- Blany-Criddle
3- Pan evaporation
4- Linacre
The program also includes an option to calculate soil field capacity, and
permanent wilting point, and maximum amount of water that could be given to fill the
soil down to a given root depth based on the soil type.
110
Nutrient Solution Uptake, CO2 Assimilation Rate, Growth, and Yield of
Cucumber Plants as affected by Irrigation Control Method in Substrate
Culture
Mi Young Roh
Protected Cultivation Division
National Horticultural Research Institute
Suwon 441-440
Republic of Korea
Yong Beom Lee
Dept. of Environmental Horticulture
The University of Seoul
Seoul 130-743
Republic of Korea
Keywords: Cucumis sativus, solar radiation, drainage rate, perlite, rockwool
Abstract
Cucumber plants (Cucumis sativus L. cv. Eunsung Baekdadagi) were grown in
perlite, rockwool, and the mixture of perlite and rockwool granules to investigate the
effect of irrigation control method on the amount of nutrient solution uptake, net CO2
assimilation rate, growth and yield responses. The frequency of irrigation was
controlled by the integrated solar radiation (ISR) of 10, 20, and 30 cal cm-2 in the first
experiment and by time clock and the ISR of 10, 20, 40, and 60 cal cm-2 in the second
experiment. By increasing the ISR level for irrigation control, in other words, with
decreasing the frequency of irrigation per a day and increasing the amount per each
irrigation, the amount of nutrient solution absorbed by one cucumber plant decreased
and that of nutrient solution drained outside beds increased in all substrates. The
amount of nutrient solution uptake was lowest in perlite and similar between in
rockwool and in the mixture at the same ISR level. At the treatments of 10, 20, and 30
cal cm-2, drainage rates were respectively 28.4, 38.3, and 46.8 % in perlite, 10.3, 23.8,
and 33.1 % in rockwool, and 11.6, 20.4, 24.9 % in the mixture in the first experiment. In
the second experiment, the amount of nutrient solution uptake was highest in the
treatment of 10 cal cm-2 and lowest in that of 60 cal cm-2. It was similar between at the
treatment of time clock and at that of 40 cal cm-2. When the frequency of irrigation was
controlled by 10 to 20 cal cm-2 and 20 to 40 cal cm-2, drainage rates were 25.7 to 30.8 %
in perlite and 23.1 to 31.4 % in the mixture, respectively. High CO2 assimilation rate,
growth and yield of cucumber plants were shown at the treatment of 10 to 20 cal cm-2 in
perlite and that of 20 to 40 cal cm-2 in the mixture.
111
Sap Flow, Trunk Diameter and Plant-water Relations Parameters as Stress
Indicators of Apricot Trees
Ruiz-Sánchez, MªC, Torrecillas, A., Nicolás,
E., Ortuño, A. and Alarcón, J.J.
Dept. Riego y Salinidad, CEBAS-CSIC, P.O.
Box 4195, 30080 Murcia
Spain
MªF, Pérez-Pastor
Dpto. Producción Agraria. ETSIA-UPCT,
Cartagena.Unidad Asociada al CSIC de
Horticultura Sostenible en Zonas Áridas
(UPCT-CEBAS).
Abstract
The aim of this paper was to study continuous and discrete plant-water-relations
parameters in mature apricot trees, in order to analyse the physiological basis of these
plant-based sensors as well to determine the most sensitive indicator of plant water
deficits. The experiment was performed during 1998-2001 in twelve-year-old apricot
trees (Prunus armeniaca L., cv. Búlida), growing under field conditions in Murcia,
Spain (semi-arid climate, with 1500 mm of average annual evaporation and 350 mm of
rainfall) in a clay loam texture soil (128 mm m-1, available soil water content, 1.45 Mg
m-3, bulk density). Trees were submitted to two drip irrigated treatments: a control
treatment irrigated at 100 % of seasonal ETc and a water deficit treatment (WD)
irrigated at 50 % of the control treatment. Diurnal courses of leaf water potentials, leaf
conductance, net photosynthesis, leaf temperature, sap flow and trunk diameter
fluctuations (TDF) were studied throughout one growing season. Deficit treatment
showed stomatal regulation as an adaptive mechanism to drought, which allows plants
to regulate water loss more effectively. Values of leaf temperature were higher in WD
than in control treatment, being, also, a good stress indicator. Net photosynthesis
showed a good correlation with leaf conductance values. Under deficit irrigation
conditions osmotic adjustment was not developed. There was a good correlation of leaf
water potential and gas exchange parameters with evaporative demand of the
atmosphere. Continuous monitoring of trunk diameter estimated as trunk growth rate
provides a sensitive indicator and could be used for automated irrigation scheduling.
The values of sap flow, which were closely related with ETo, were reduced in the deficit
treatment respect to the control trees during all the growing season, although higher
differences were obtained in spring.
112
Effect of Irrigation Water Acidifying on Quality and Quantity of Racemose
Carnation Cutflower CV.. “ARANKA”.
Mehdi Saidi, A. Khalighi. and M.Kaafi
Abstract
This research was studied during 2000-2001 in one of the greenhouses of
khaadem nursery, Varaamin, Iran. In this research the effect of irrigation water
acidifying on the quality and quantity of racemose carnation cutflower var. “
ARANKA” was studied and treatments included two acidity levels of irrigation water (
A1: normal with pH=7.6 and A2: Acidic water with pH= 6 ± 0.1) . At the end of the
experiment, results showed that irrigation water acidification increased number of stem
per plant and square meter, number of closed buds and total number of buds on stem
and flower post harvest vase life, Potassium, Calcium, Magnesium, Boron, Iron and
decreasing on Nitrogen leaf content, significantly. But its effect on the length and
thickness of stem, number of open buds on stem , stem flexibility and Phosphorus leaf
content weren’t significant.
113
Effect of Oxygen in the Root Environment on Yield and Growth
Parameters under Soilless Crop
M.C. Salas, Urrestarazu, M. and F. Ventura
Dpto. Produccion Vegetal, Universidad de Almeria, Spain
[email protected]
Keywords: hydroponics, oxygen deficiency, nutrient solution, root, organic substrate, melon
Abstract
Oxygen deficiency in the root zone may induce a number of plant reactions, such
as wilting, poor growth or even root death. In hydroponic systems with a low substrate
volume, elevated water temperatures during summer may lead to oxygen deficiency due
to reduce oxygen solubility and more rapid use by microorganisms and roots. The
dissolved oxygen in the nutrient solution has a direct influence on root function,
particularly respiration. Oxygen must be present in the water around the roots and its
deficiency will depress root growth and nutrient uptake. With increasing temperature,
the solubility and hence the availability of oxygen in the water will be reduced whereas
the plant’s demand for oxygen will increase. The oxygen content of the solution is
directly influenced by the hydroponic irrigation system and substrate. There are a lot of
ways of increasing oxygen diffusion and is also possible to oxygenate the solution in the
substrate by adding air under pressure. When the volume of the available water in the
substrate is high but the rate of water uptake by the plants is low while the supply of
nutrient solution depends on the water consumption by the crop, the solution in the root
zone cannot be renewed as frequently as desired with detrimental effects on supply of
oxygen to the roots. Although oxygen supply to nutrient solution has a positive effect in
the cultures, its yield not always is assured. Thus, the aim of this study was to evaluate
the feasibility of adding air under pressure to oxygenate the nutrient solution in the
substrate for growing of plants of melon utilising soilless system. The experiment was
carried out under cold greenhouse conditions at South Spain (Almeria) using aerated
and non-aerated pine fiber bags. The shoot and root growth; also water uptake and the
emission of nitrates and phosphates were registered. It was also evaluated the yield and
quality of fruits. As conclusion, the oxygen supply of the nutrient solution by adding
pure oxygen under pressure in substrate contributes to improve growth, an increase in
the ion absorption, and contributing with an increase of yield.
114
Influence of Water Salinity on Growth and Water Relations of Loquat
Plants Grafted on two Rootstocks.
M.J. Sánchez-Blanco, T. Ferrández, and A.
Torrecillas
Dept. of Riego y Salinidad, CEBAS-CSIC
P.O. Box 4195, 30080 Murcia, Spain
E. López Gómez, J. Mataix Beneyto and
M.F. García-Legaz
Dept. of Agroquímica y Medio Ambiente,
UMH, P.O. Box 43, 03300 Orihuela
(Alicante), Spain
Abstract
The purpose of this paper was evaluate the effect of different levels of salinity on
the response of loquat plants grafted on franco and Anger rootstocks to know the
influence of the rootstock on their degree of resistance. Water and growth parameters,
gas exchange and mineral content were used as stress indicators. The experiment was
performed in two-year-old loquat “Algerie” trees (Eriobotrya japonica Lindl.) grafted
on franco and Anger stocks, growing in a glasshouse with partially controlled
conditions. Trees were submitted to five saline treatments for 5 months: 5 (control), 25,
35, 50 and 70 mM NaCl nutrient solutions. At the end of the experiment, the
physiological traits of salt tolerance that differed between both scion-rootstock
combinations were studied. The total dry weight of loquat plants on Anger rootstock
was unaffected by salinity, whereas in those grafted on franco, a significant reduction in
total dry weight was noted, the plants treated with 50mM and 70mM presenting a
substantial degree of defoliation and foliar necrosis. Plants grafted onto Anger showed
lower Na+ contents in leaves than those grafted onto franco, demonstrating that it is
an efficient Na+ excluder. Under low salinity levels the accumulation of Cl- in both
rootstock-scion combinations was similar. The sodium had a more adverse effect than
chloride on the dry weigh, which could be related with the stronger influence on the
photosynthesis level in plants grafted on franco. Lower leaf water potential values at
predawn were observed in plants grafted on franco than those grafted on Anger at
moderate salinity levels. Nevertheless, those differences disappeared at midday as a
result of the effect of the environmental factors. Osmotic adjustment permitted the
maintenance of leaf turgor at predawn and midday in treated plants grafted on Anger,
but did not prevent a decrease in leaf turgor in franco.
115
Field Salinity Tolerance of San Joaquin Valley Pistachios: Determining ET
& Water Stress in Long Term Field Trials
Blake Sanden
Irrigation & Agronomy Farm Advisor, Kern
County, (661) 868-6218;
Louise Ferguson
Extension Pomologist, Department of
Pomology, UCD @ Kearney Agricultural
Center
Steve Grattan
Plant Water Relations Specialist, Department
of Land, Air and Water Resources, UCD
Heraclio C. Reyes
Laboratory Assistant, Department of
Pomology, UCD @ Kearney Agricultural
Center
Abstract
In many areas of Iran pistachios have been grown for decades using saline
irrigation water. Research there and a 1 year sand tank study at the USDA Salinity
Lab in Riverside, California indicate that most pistachio rootstocks can tolerate as
much as 12 dS/m EC in the irrigation water without significant decline in growth and
production. Starting in 1994 five different salinity treatments of 0.5, 2, 4, 6, and 8 dS/m
were applied to 4 different pistachio rootstocks budded to a Kerman scion in a six year
old orchard on the westside of the San Joaquin Valley. Trees are irrigated with one, 55
lph (14.5 gph) micro sprinkler and planted to a 5.2 m by 6.1 m (17 x 20 foot) spacing.
Saline irrigation treatments were formulated to simulate the quality of local drainage
water, with a Na:Ca ratio of 5:1 and B at 10 ppm. After two years, there were no
significant decreases in marketable yield among rootstocks or treatments. In 1997, the 2
dS/m treatment was changed to 12 dS/m and treatments continued @ 0.5, 4, 8 and 12
dS/m. Soil water content depletion (to 1.4 m) between irrigations was determined by
neutron backscatter. The soil moisture volumetric calibration was best fit to a
logarithmic curve in this fine silty clay loam. Due to the large number of trees in the
trial (64) only 1 neutron probe access tube per tree, sited in an identical location relative
to each tree and microsprinkler, was originally used to develop an estimate of
“comparative cumulative seasonal transpiration”. For 1999 and 2000, this comparative
seasonal ET in the salinized trees, was 66, 53 and 46% of the control trees for the 4, 8
and 12 dS/m treatments, respectively. Despite this significant difference in soil water
uptake, all plant-based measurements of leaf water potential, photosynthesis, stomatal
conductance and transpiration showed no significant difference. Visual assessment of
tree vigor likewise showed no difference. Far-reaching roots from the salinized trees are
most likely extracting fresh water from adjacent trees receiving fresh water. In
February 2001, the borders of all plots were trenched and fitted with a 6 mil plastic
barrier to a depth of 1.5 m to eliminate the crossover of shallow roots from saline to
non-saline plots. The number of monitored trees was reduced to 32 with an increase to
4 neutron probe access tubes per tree installed to a depth of 1.8 m. Seasonal ET
estimated by a weighted “zone” approach was 8 to 23% greater than seasonal ET
estimated by the simple average soil moisture depletion for all access tubes on one tree.
116
This method resulted in a 2 year average ET for the control treatment of 1350 mm,
11.7% greater than ET calculated from local weather data and published crop
coefficients. ET of saline treatments was 91, 79 and 65% of the control under this
configuration for the 4, 8 and 12 dS/m treatments, respectively. The coefficient of
variation for individual tree seasonal ET ranged from 32 to 50% (a standard error of
104 to 287 mm), depending on treatment.
Differences in Hydraulic Architecture Account for Near-isohydric and
Anisohydric behaviour of two Field-grown Grapevine Cultivars during
Drought
Hans R. Schultz
Institut für Weinbau und Rebenzüchtung
Forschungsanstalt D-653660 Geisenheim
Germany
Abstract:
A comparative study on stomatal control under water deficit was conducted on
grapevines of the cultivars Grenache, of Mediterranean origin, and Syrah of mesic
origin, both grown near Montpellier, France and Geisenheim, Germany. Seasonal and
diurnal measurements of leaf photosynthesis (A), stomatal conductance (g) and leaf
water potential (LWP) indicated that Syrah exhibited anisohydric stomatal behaviour
with higher maximum g at similar levels of water deficit (expressed as pre-dawn LWP)
as Grenache and daytime LWP which markedly decreased during the day and was
lower for stressed than for watered plants. Grenache exhibited isohydric stomatal
behaviour where LWP did not drop significantly below the minimum LWP of watered
plants. When g was plotted versus leaf specific hydraulic conductance, KL,
incorporating leaf transpiration rate and whole plant water potential gradients,
previous differences between varieties disappeared both on a seasonal and diurnal scale
suggesting that isohydric and anisohydric behaviour was regulated by hydraulic
conductance. Pressure-flow measurements on excised organs from plants not previously
stressed revealed that Grenache had a 2-3 fold larger hydraulic conductance per unit
path length (Kh) and a 4-6 fold larger leaf area specific conductivity (LSC) in leaf
petioles than Syrah. Differences between internodes were only apparent for LSC and
were much smaller. Cavitation detected as ultrasound acoustic emissions on air-dried
shoots showed higher rates for Grenache than Syrah during the early phases of the drydown. It is hypothesised that the differences in water conducting capacity of stems and
especially petioles may be at the origin of the near-isohydric and anisohydric behaviour
of g.
117
Using Water Balance Models for Irrigation Scheduling
S. Sechi, A. Arca and Spano
1Department of Economics and Woody Plant
Ecosystems, University of Sassari, Italy
M. Fiori
2Agrometeorological Service of Sardinia –
SAR, Sassari Italy
P. Duce
3Institute of Biometeorology, National
Research Council of Italy, Sassari, Italy
Abstract
This study was conducted in the framework of COST 718 action, Meteorological
Applications of Agriculture, Working Group 2 Crop Pest & Disease and Plant Model,
Irrigation Models Comparison. The objective of this paper is to evaluate two water
balance models, CROPWAT and IRRFIB, developed by FAO and Hydrometeorological
Institute of Slovenia, in order to provide basic information on irrigation management.
The models were compared with IRRINET, a water balance model developed
specifically for the agricultural areas of Sardinia (Italy). CROPWAT and IRRFIB
models calculate crop water requirements and provide recommendations to improve
irrigation scheduling. In particular, CROPWAT is a practical tool to calculate
reference evapotranspiration, crop water and irrigation requirements, and to design
and manage irrigation schemes. IRRFIB computes the soil water balance and calculates
the available water content in the root zone. The output files can be directly used for
irrigation system design and for the calculations of water volumes for irrigation
management. IRRINET is the main operating instrument of the Agrometeorological
Service of Sardinia for extension activities on irrigation scheduling. It gives irrigation
scheduling from soil water balance using data provided by the users. Meteorological
data from two weather stations located in Sardinia were used to compare the outputs of
the models for two years on maize. The resulting soil water balance and irrigation
scheduling were compared.
118
Physiological Indicators of Plant Water Status as Criteria for Irrigation
Scheduling in Table Grapes cv. Crimson Seedless, Irrigated by Drip.
G. Selles; R. Ferreyra E.;
Instituto Investigaciones Agropecuarias. CRI.
La Platina. Santa Rosa 11.610 Santiago. Chile.
[email protected]
H. Silva R..
Facultad de Ciencias Agronómicas
Universidad de Chile
Santa Rosa 11611, Santiago. Chile
Abstract
Several physiological indicators of plant water status ( stem water potential, ΨS
, leaf water potential ΨL, maximum daily trunk growth, MDG and maximum daily
trunk shrinkage, MDS ), were tested as criteria for irrigation scheduling in table grapes
cv Crimson Seedless irrigated by drip, growing in a depth (2 m) clay loamy soil, at the
Aconcagua Valley, Chile. Four irrigation treatments were applied : T1, 100% of crop
evapotranspiration (ETc), T2, 75% of ETc, T3, 50% of ETc, all over the season, .and
T4, with a variable amount of water (100, 50 and 25 % of ETc) all over the season.
Leaf water potential and stem water potential were measured at midday using a
pressure chamber. Trunk daily growth and shrinkage were measured with electronics
dendrometers . The soil water changes in the soil profile were also measured.
MDG was the most responsible indicator to water stress, showing differences
among irrigation treatments before the others indicators tested (MDS, ΨS .and ΨL).
119
Midday Stem Water Potential for RDI management and Water Stress
Diagnosis in Tree and Vine Crops.
Ken Shackel, Jodee Ellett, Scott Johnson, Allan Fulton, Rick Buchner
Pomology Department, University of California, Davis, CA.
Abstract
Over the past number of years, midday stem water potential (SWP) has become
an increasingly routine method for irrigation management in a number of tree crops
(prune, almond, walnut), and in some vineyards in parts of California and elsewhere.
One key practical advantage of SWP is that it is highly reproducible, typically only one
leaf per plant is required, and plant-to-plant differences are consistent over much of the
season. Consistency in plant-to-plant differences is advantageous because a small group
of plants can be chosen as representative of a large field after an initial period of more
extensive sampling. In prunes, almonds and walnuts a reliable estimate of the SWP
exhibited by a plant experiencing no limitation in soil water availability (field capacity
conditions) can be made for most of the season simply from midday air VPD. This fully
irrigated “baseline” value can be used as a reference that takes local weather conditions
into account. In wine grapes and peaches there appears not to be a stable SWP/VPD
relation, but despite this lack of a good relation in wine grapes, difference is midday
stomatal conductance were well correlated to differences in midday SWP on any given
day. Another advantage of SWP is that the same absolute values appear to be useful as
guidelines for irrigation from year to year. An SWP-based RDI regime that improves
fruit soluble solids content has been proposed and is in common use in prunes, and a
similar approach that improves hull split in almonds is currently being evaluated. In
one almond orchard, a chronic problem of uneven hull splitting in different parts of the
field was diagnosed as related to differences in SWP, and irrigation based on SWP was
used to solve the problem.
120
A Study on Okra / Pea Intercropping – Microclimate Modification and
Yield Advantages
Ramzi K. Sharaiha
Faculty of Agriculture, Univ. of Jordan,
Department of Horticulture & Crop Science
E-mail “[email protected]
Anwar Battikhi
Faculty of Agriculture, Univ. of Jordan,
Department of Land Water & Environment
Abstract
This experiment was conducted at the Faculty of Agriculture Research Station,
University of Mu`tah in Rabbah, South Jordan, during summer growing season 2000.
The objective of this experiment was to study the effect of the following microclimatic
factors: - air and soil temperature, light intensity, soil moisture storage (SMS),
evapotranspiration (ET), and water use efficiency (WUE) on the yields of okra and pea
as they were grown under sole cropping and intercropping systems with four row
arrangements
(1: 1, 1: 2, 2: 1, 2: 2). Okra and pea gave the highest yields when grown in 1: 2
and 2: 1 intercropping row arrangements. The increase of pea yield was 3.51 and 3.32
ton ha¯¹ respectively, while that of okra yield was 6.52 and 5.94 ton ha¯¹ respectively,
over their sole crops. The increase of pea yield could be related to the reduction of air
heat unit (by 45 and 15.3), soil heat unit (by 123 and 133.3), ET (by 45 and 135 mm), in
addition to an increase of WUE (by 0.144 and 0.146 ton/ha/cm) as pea was grown with
okra under 1: 2 and 2: 1 row arrangements, respectively, whereas light intensity and
SMS were not effective on pea yield. On the other hand, the increase of okra yield was
associated with an increase of air heat unit (by 29 and 26), soil heat unit (by 53 and 55.1)
and WUE (by 0.261 and 0.242 ton/ha/cm) under the same row arrangements
respectively. However, the other microclimatic factors were not effective on okra yield.
The land equivalent ratio (LER) values under all intercropping treatments were greater
than one, which gave an indication for the superiority of the intercropping over the sole
cropping.
121
Performance of Landscape Ornamentals Given Irrigation Treatments
Based on Reference Evapotranspiration
D.A. Shaw and D.R. Pittenger
University of California Cooperative Extension
San Diego County
5555 Overland Avenue, Building 4
San Diego, CA 92123 USA
Abstract
The use of reference evapotranspiration (ETo) information for scheduling
irrigations and for determining water allotments for landscapes is being adopted by
water purveyors, agencies, and landscape architects and maintenance personnel. There
is little research-based information relevant to landscape ornamental plant materials.
The objectives of this project were to determine the response of 30 ornamental species
to irrigation treatments relevant to ETo and to further refine estimates of ornamental
plant water needs for acceptable aesthetic appearance. Experimental plots were
established in Encinitas, California, USA, consisting of nine 180m2 blocks allowing
three irrigation treatments replicated three times. Four plants of each of 30 species were
planted into 6m2 experimental units within the drip-irrigated blocks. Irrigation
treatments were initiated in 1996 and consisted of 0.36, 0.24, and 0.12 ETo with
irrigation frequency determined by projected soil moisture deficit of 13mm. During
1997 and 1998, irrigation treatments were adjusted to 0.36, 0.18, and 0.0 ETo. Aesthetic
quality was not affected by irrigation treatment in 14 of the species studied. Three of
these species showed a trend towards better quality with less water. The aesthetic
quality of 14 species was reduced with reduced irrigation amounts. Many of these
species performed well at the 0.36 and 0.18 ETo treatments but suffered at the 0.0 ETo
level. Two ornamental species had to be severely pruned or removed to reduce
competition in the small plot size. The results of the study show that ETo treatments
affect landscape quality for some species and acceptable aesthetic appearance can be
maintained with reduced irrigation.
122
Determination of a Critical Nitrogen Dilution Curve for Rainfed and
Irrigated Burley Tobacco.
M.I. SIFOLA and A. ZARONE
Department of Agricultural Engineering and Agronomy, University of Napoli "Federico II",
Via Università 100, 80055 Portici, Napoli (Italy).
Abstract
The nitrogen (N) concentration in field-grown crops is inversely related to the
rate of plant growth due to dilution effects. Our objective was to determine the critical
N dilution curve for irrigated and non irrigated plants of ‘Burley’ tobacco (Nicotiana
tabacum L.) grown in Campania, Italy, over two growing seasons. Four fertilization
rates (0, 120, 240 and 360 kg N ha-1) were factorially combined in each year. Dry matter
(DM) and Kjeldahl N concentration of leaves and stems were determined by sampling
five times during the growing season starting from the rosette stage (39 and 35 days
after transplanting, DAT, in 1998 and 1999, respectively) through leaf ripeness (67
DAT) in 1998 and commercial harvest (101 DAT) in 1999. The relationship between N
concentration and DM was used to calculate the minimum N concentration which
produced the maximum DM for each growth stage, that is the critical N points (Nct).
Nct varied from 4.2 to 2.2% when DM ranged between 27 and 320 g per plant. The
following critical N dilution curve was obtained using statistical procedures: Nct = 8.459
x –0.218 (R2 = 0.634**, n = 12). The critical N dilution curve was not influenced by the
year of study. Irrigation did not affect either Nct or the critical N dilution curve. The
critical N dilution curve is useful to optimize N fertilization practices for ‘Burley’
tobacco plants under Mediterranean climate conditions.
123
Optimizing Processing Tomatoes Production as a Function of Water
Depths and Nitrogen Rates
W.L.C. Silva, W.A. Marouelli, H.R. Silva and C.L. Moretti
National Vegetable Crop Research Center – Embrapa Vegetables
Caixa Postal 218, CEP 70359-970 Brasilia, DF, Brazil
E-mail: [email protected]
Abstract
Nearly eighty percent of all processing tomato crop in Brazil is grown in the
central part of the country, during the dry season, mostly irrigated by sprinkle systems
especially center pivots. In spite of that, there is neither irrigation nor nitrogen
fertilization management scheme that fully suits the crop needs. Five gross water depths
(564, 456, 349, 242 and 117 mm/growing season) and five nitrogen rates(0, 75, 150, 225
and 300 kg/ha) treatments were combined in a line-source experiment using a sprinkle
irrigation system in order to obtain tomato response functions to the referred factors.
Irrigation management was based on the 40 kPa tension monitored with tensiometers
installed in the strip corresponding to the depth of 456 mm. Total nitrogen was
partitioned into three equal side-dress applications (at transplanting, 21 and 42 days
thereafter). At harvest, variables such as total and marketable yield, percent of rotten
fruit, blossom-end rot, fruit color, soluble solids content, firmness and acidity were
evaluated. There was no significant effect (p>0.05) for both nitrogen rates and their
interaction with water depths. Some variables showed quadratic response as a function
of water depths. Maximum marketable yield was 121.7 ton/ha which was achieved with
a gross depth of water of 447.6 mm.
124
Water Consumption of a Vineyard in Different Slopes.
Silvestre, J.
Estação Vitivinícola Nacional, 2565-191
Dois Portos Portugal
[email protected]
Ferreira, M. I.
2Instituto Superior de Agronomia, UTL,
Tapada da Ajuda, 1349-017 Lisboa, Portugal
[email protected]
Abstract
The influence of topography in water use was studied for a vineyard plot with
increasing slope. Transpiration of Vitis vinifera L, cv. Castelão) was monitored, for a
vegetation period, with the sap flow Granier method. Soil water content and predawn
leaf water potential during the same period were also followed. Three locations facing
the same direction were selected in the plot, where slopes were 3%, 10% and 17%. No
evidence of severe water stress was found during the experiment. However, some
differences were found between slopes after veraison, more pronounced for the two
higher slopes. The seasonal evolution of sap flow rates agreed well with the predawn
evolution. Daily sap flow rates were higher between bloom and veraison and at the
slopes less pronounced. At an annual basis, the transpiration of the vines at the
positions with lower slopes were very similar, while the ones located at the slope more
pronounced showed a reduction greater than 20%, as a result of a smaller vigour.
125
Soil CO2 Flux Measurements in Vineyard Ecosystem
C. Sirca, C. Asunis, D. Spano and A. Arca
Department of Economics and Woody Plant
Ecosystems, University of Sassari, Italy
P. Duce
Institute of Biometeorology, CNR-IBIMET,
Sassari, Italy
Abstract
Many recent studies on climate change indicate the soil as a major source and
sink for atmospheric CO2. Production of CO2 in soil results from the oxidation of soil
organic matter and the respiration of plant roots. Researchers do not agree on a
standard method to measure CO2 fluxes from soil. Knowledge of soil respiration rate
from cultivated ecosystems is important for determining the role of this ecosystems in
the global carbon balance. This paper presents the results obtained from short-term
measurements conducted in two vineyards located in typical Italian areas of cultivation.
Soil respiration rates were measured using soil chambers in an open-system
configuration. Plant-to-plant polyvinylchloride collars (98.5 cm2) were inserted at a
depth of 2 cm into the soil. Fluxes of CO2 were measured approximately every four
hours by sealing the chambers over the collars. Data showed a typical CO2 flux trend
during the day, with a maximum of CO2 released at midday. Bigger differences were
found in relation to spatial location of chambers than time of the day. Moreover, the
results suggest a good relationship between soil CO2 efflux and soil temperature. In
addition, roots distribution and activity can explain the variability of soil respiration
between chambers. The observed variability indicates that correct measurements of soil
CO2 efflux require an adequate number of samples and a good sample distribution.
126
A Simulation Model for ET of Applied Water
R.L. Snyder
University of California, Land, Air and
Water Resources, Davis, Calif. USA
S. Geng
University of California, Agronomy and
Range Science, Davis, Calif. USA
M.N. Orang and J.S. Matyac
California Department of Water Resources,
Division of Planning, Sacramento, Calif.
USA
Abstract
The California Department of Water Resources and the University of California
recently developed a weather generator application program “SIMETAW” to simulate
weather data from climatic records and to estimate reference evapotranspiration (ETo)
and crop evapotranspiration with the simulated data. In addition, simulated daily
rainfall, soil water holding characteristics, effective rooting depths, and ETc are used to
determine effective rainfall and to generate hypothetical irrigation schedules to estimate
the seasonal and annual evapotranspiration of applied water (ETaw), where ETaw is
the net amount of water needed to produce a crop. The actual water requirement is
estimated by dividing by the application efficiency. Weather generators allow one to
investigate how climate change might affect the water demand in California. In this
paper, we will discuss how the simulation model uses monthly input data to generate
daily weather data over variable periods of record and how ETaw is determined.
127
Estimate of Mass and Energy Fluxes over Grapevine using Eddy
Covariance Technique
D. Spano
Department of Economics and Woody Plant
Ecosystems, University of Sassari, Italy
R.L. Snyder
Department of Land, Air and Water
Resources, Davis, CA, USA
P. Duce
Institute of Biometeorology, CNR-IBIMET,
Sassari, Italy
Abstract
The impacts of climate on carbon storage and carbon pools in tree crops and
vine systems are inadequately investigated because of their small sizes in comparison to
the large extent of forest ecosystems and the unrecognized importance of their
ecological role. In the last decade, eddy covariance technique has chosen as a standard
reference for estimating carbon and water vapor exchanges. Eddy covariance is
essentially a direct measurement of the upward and downward fluxes and uses high
frequency measurements of vertical component of the wind speed and scalars. The
objective of this study was the assessment of energy and mass exchanges between
grapevine surface and the atmosphere using eddy covariance technique. The estimates
of energy budget components and carbon and water vapor fluxes were made in two
vineyards located in Tuscany and Sardinia, Italy. An eddy covariance system, which
includes a three-dimensional sonic anemometer and an open-path infrared gas analyzer
was used to monitor half-hourly values of carbon dioxide (Fc), water vapor (λE), and
sensible heat (H) fluxes above the vegetation. Flux data were taken in July and August
of two consecutive years. In addition, net radiation (Rn) and soil heat flux (G) density
data were collected simultaneously to test the eddy covariance measurements by closing
the energy balance. The results of the energy balance closure indicated a good accuracy
of the data set. The analysis of the radiative budget showed daily Rn values of about 14
MJ m-2 and diurnal albedo values of about 0.15. Rn was partitioned between H and λE
in relation to weather conditions. The Fc values ranging between -8 and -10 µmol CO2
m-2s-1 were taken by the vegetation during daytime. The daily net C budget resulted in
about 2.14 g m-2 d-1 showing that the vineyard performed as a carbon sink.
128
Distribution of the Rooting System in Soil Depending on the Irrigation
Methods within the Hilly Region of Pitesti-Maracineni in the Golden
Delicious Apple Cultivar
N. Tanasescu and Cr. Paltineanu
Fruit Research Institute, 0312 Pitesti-Maracineni, Romania
Keywords: MM 106 rootstock, root cross-sectional area, irrigation depth
Abstract
Although the rooting system of fruit trees have a heredity-determined pattern,
the action of some external factors like soil, climate, presence of a shallow hard rock or
groundwater as well as the technological works can induce important changes in the
fruit tree rooting system distribution in soil. The present paper shows the effects of
various irrigation methods on the distribution of roots in the Golden Delicious apple
cultivar grafted on MM 106 rootstock under the specific conditions of the hilly region of
Pitesti-Maracineni, Southern Romania. The mean annual temperature was about 9.6˚ C
and rainfall 650 mm. More than one irrigation methods were used: sprinkler irrigation
(SI), micro-sprinkler irrigation (MI), and drip irrigation (DI), as well as a control, nonirrigated treatment (NI). The experiment was conducted over a period of 7 years. Trees
were planted 3.6 m between rows and 1.5 m spaced on the row. Soil profiles were
excavated down to 1 m depth at mid-distance between the representative trees under
study and various tree root classes were determined on a 1 m2 soil wall area. The results
obtained showed that the irrigation method used in apple orchards induced a specific
tree root distribution in the soil profile and also a specific value of the sum of root crosssectional area. Thus, in the DI treatment about 43% of tree roots were developed within
the 0-20 cm depth and only about 28% were on the 20-40 cm depth. On the contrary,
there was an opposite trend in the case of NI, whereas the other treatments manifested
intermediate values. The sum of cross-sectional area of tree roots did not differ much
between treatments, and had maximum values (13%) within the SI and minimum
values (11%) in NI. There was found a direct, significant correlation between the sum of
cross-sectional area and fruit yield, more intensely for the MI. This study revealed also
from this point of view that the MI and DI were the best methods used under these
natural and technological conditions discussed here.
129
Fruit Yield and Tree Growth versus Crop Evapotranspiration for Various
Irrigation Methods within the Hilly Region of Pitesti-Maracineni in the
Golden Delicious Apple Cultivar
N. Tanasescu and Cr. Paltineanu
Research Institute for Fruit Growing, 0312 Pitesti-Maracineni, Romania
Keywords: MM 106 rootstock, tree trunk cross-sectional area, irrigation depth
Abstract
The present paper investigates the effects of various irrigation methods on fruit
yield and tree growth of the Golden Delicious apple cultivar grafted on MM 106
rootstock under the specific conditions of the hilly region of Pitesti-Maracineni,
Southern Romania. The mean annual temperature was about 9.6˚ C and rainfall 650
mm. More than one irrigation methods were used: sprinkler irrigation (SI), microsprinkler irrigation (MI), and drip irrigation (DI), as well as a control, non-irrigated
treatment (NI). The experiment was conducted over a period of 7 years. Trees were
planted 3.6 m between rows and 1.5 m spaced on the row. Fruit yield and annual
growth in tree trunk cross-sectional area (TTCSA) were measured every year within
each treatment investigated. The experiment design was performed as a split-plot
method with three replicates for each treatment. Crop evapotranspiration was covered
by rainfalls, irrigation application, and soil moisture reserves and was calculated from
field data based on the water balance equation. For the area studied irrigation was
needed especially during the July through September period, but crop
evapotranspiration generally differed among the four irrigation treatments studied. MI
and SI treatments showed the highest fruit yield values that were statistically insured.
Fruit yield correlated positively to both irrigation depth during the entire growing
season and crop evapotranspiration both in individual irrigation treatments and when
all data were considered together. TTCSA was significantly different among the
irrigation method treatments in all years of experiment. It was significantly and
positively correlated to annual irrigation depth. Micro-sprinkler and drip irrigation
induced a more efficient way of water application utilization in the Golden Delicious
apple orchard investigated. This was why these two treatments were the most
recommended to be extended in orchard farming.
130
Use of a Novel, Tensiometer-based Control System to Reduce Irrigation of
cut flower Dianthus caryophyllus ‘Santorini’ whilst maintaining Flower
Yield and Quality
Robyn D. Taylor and Brian W. W. Grout
Postgraduate School, Writtle College, Chelmsford CM1 3RR, UK
Abstract
Production of many cut flowers is shifting toward developing countries and
concerns are being raised about environmental impact, particularly with regard to
water utilisation. Concerns exist over the effects of extraction together with pollution of
waterways by chemical run off and leaching. An effective control and delivery system
for irrigation would allow limited and vulnerable water resources to be managed
effectively to protect the surrounding environment whilst maintaining the high quality
production demanded by valuable export markets. A tensiometer-based irrigation
system monitors soil moisture tension and uses this data to trigger water supply
automatically. Such a system was used to investigate the effect of soil-tension controlled
irrigation on cut flower Dianthus carophyllus ‘Santorini’, used because of its popularity
and economic significance. Five treatments covered a range of moisture tensions from –
15 kPa to -75 kPa, the upper limit of most commercial tensiometers. Harvested flowers
were graded and sized according to EC Regulation 316/68. Irrigation triggered by a
soil moisture tension of -15kPa produced the most long stems (>60cm) but with
inconsistent quality. A triggering tension of –45 kPa produced the most flowers and at
the highest quality, particularly at stems lengths >60 cm. Overall, no decline in flower
quality or median stem length was noted until the soil tension reached –75 kPa before
irrigation.The investigation showed that water resources can be managed with the use
of tensiometers to reduce water input to maintain and, possibly, improve flower yield
and quality.
131
Irrigation Scheduling of Drip-irrigated Vegetable Crops grown in
Greenhouses using Continuous Soil Moisture Monitoring
R.B. Thompson and M. Gallardo
Depto. de Producción Vegetal, Universidad
de Almeria, 04120, Almeria, Spain
Mª.D. Fernández
Cajamar, E.E. Las Palmerillas, Apdo. 250,
04080 Almeria, Spain
Abstract
Approximately 24,000 ha of plastic greenhouses are used for intensive
horticultural production in the coastal region of Almeria, in SE Spain. Eighty percent
of cropping is in soil, the rest in hydroponics. Drip irrigation (above-ground tape) is
used, with one dripper per plant. Irrigation management is mostly based on local
experience, with considerable variations in water use for similar levels of production.
Most irrigation water is obtained from local aquifers with extraction exceeding
replenishment. There is a clear need for improved irrigation management. There is
considerable heterogeneity among greenhouses, and in planting dates. Continuous soil
moisture monitoring (CSMM) enables irrigation to be "tailored" to the characteristics
of individual greenhouses and crops. Procedures were developed to use the
EnviroSCAN (ES) capacitance sensor system for irrigation management in this system.
ES probes consisted of sensors at 15, 25, 35 and 45 cm soil depth. One probe was
located close to the plant and its corresponding dripper, and another was placed in an
"edge of bulb" position. The first probe position enabled assessment of vertical
drainage, infiltration, and plant uptake, and the second probe position enabled
assessment of horizontal water movement and general tendencies in root zone water
content. Irrigation management was based primarily on restricting both vertical and
horizontal drainage. Pepper was grown to compare irrigation management using
CSMM and manual tensiometers (10–30 kPa). The crop was transplanted in 4 July
2000 and grown until 27 November 2000. Commercial fruit production (6.3 and 6.7 kg
m-2) and applied irrigation volumes (296 mm) were very similar using both irrigation
management systems. These data suggested that practical issues and cost would be the
major factors influencing grower choice. The relative advantages of CSMM automatic data collection, continuous data, remote data retrieval, less maintenance etc.
have to be considered against the much higher initial cost.
132
Influence of Irrigation and Fertilization on Performances of Young Apple
Trees
Z. Cmelik
S. Tojnko
Faculty of Agriculture University of Maribor, Faculty of Agriculture University of Zagreb,
10000 Zagreb, Croatia
2000 Maribor, Slovenia
Keywords: Malus x domestica, growth, yield, internal and external fruit quality
Abstract
Investigations of the effect of irrigation with application of ‘Polyfeed’ fertilizer in
comparison with broadcast nitrogen fertilization without irrigation on tree
performances of young apples ‘Golden Delicious’ and ‘Pinova’, grafted on M9 rootstock
was conducted. Two orchard experiments were established, one with ‘Golden Delicious’
during 2nd and 3rd year after planting and the other one with ‘Pinova’ during 2nd
vegetation, grown at a spacing of 3.2 x 0.7 m and trained to slender spindle. The results
showed no significant effect of applied treatments on tree vegetative performances and
internal fruit quality attributes (firmness, soluble solid concentration and starch index)
of both cultivars. However, irrigation improved fruit size. An additional benefit of
irrigation was higher yield per tree. Obtained results indicated positive effects of
irrigation on the tree performances in the high density apple orchard during tree
establishment.
133
Phytomonitoring in Irrigation Scheduling of Horticulture Crops
Y.Ton and M.Kopyt
PhyTech LTD., Yad Mordechai, 79145, Israel
Abstracts
There are two standard techniques for scheduling irrigation of orchards: soil
moisture monitoring and evaluation of evapotranspiration made with the use of a
standard pan or Penman-Monteith model. Limitations of these techniques are well
known. Nowadays, the use of physiological indicators for assessing the dynamics of
plant water status has attracted the attention of many growers and experts. Large-scale
field tests of the phytomonitoring technique and instrumentation were carried out in
1998 – 2002. Several dozen phytomonitoring systems were installed on apple, plum,
grapes, peach, kiwi, mango, citrus, avocado and persimmon plants. Besides common
environmental factors, the trunk, shoot and fruit growth were monitored. Two
indications were used for analysis: diameter maxima daily trend (DMT) and daily
contraction amplitude (DCA). In many cases, the midday stem water potential (WP)
data were also available. The main results were following:
High and quick sensitivity of trunk, shoot and fruit to watering in case of soil
water deficit make them good indicators for irrigation control.
Good correlation between WP, trunk/shoot DCA and vapor pressure deficit
(VPD) was found in well-watered crops.
In case of deficit irrigation and/or dry nighttime air conditions the correlation
was low. The problem was found in method of DCA determination. Commonly, the
DCA is determined as a difference between predawn maximum and daytime minimum.
However, in dry conditions, water reserves in plants are not completely replenished at
night, resulting in depression of predawn maximum. The alternative method comprises
a potential maximum diameter baseline (PMDB) instead of actual predawn maxima.
The recalculation rises the R2 value to 0.8 - 0.9.
The ratio of the modified DCA and VPD (DCA/VPD) was a good indicator of
plant water status both in well-watered and deficit irrigated crops.
The DMT was a good indicator of soil water availability because of its close
relationship to predawn water potential.
Most of tests were carried out on commercial plots. The tests were focused on
two objectives: good yield with less water. Many growers reported about considerable
saving of water and/or higher yields.
134
Irrigation Water Use by California Strawberries
Thomas J. Trout and Jim Gartung
USDA-Agricultural Research Service
San Joaquin Valley Agricultural Sciences Center
9611 S. Riverbend Ave, Parlier, CA 93648
Strawberry is a high value crop in California ($800 million annual value) that is
grown in coastal valleys where water supplies are limited and expensive. Because
strawberries are very high valued and believed to be sensitive to water stress, growers
try to insure water applications are sufficient to not decrease yield or quality. All
strawberries are grown with drip irrigation on raised beds with plastic mulch.
Irrigation application and scheduling is generally based on grower experience, rather
than scientific techniques. As with many horticultural crops, crop coefficients are not
well known. Through field plot studies in which strawberries were grown with varying
levels of water application based on ETo and canopy cover measurements, we
determined that percent canopy cover is a good estimate of a crop coefficient for
strawberries. Yields of fresh market fruit declined with underirrigation, but not as
much as expected. Over-irrigation did not result in yield loss. Measurements on
grower fields indicated some growers overirrigate by as much as 50%.
Drought Resistance: A concept without a measure! Where do we go from
here to understand drought performance of ecosystems to crops?
Mel Tyree
USDA Forest Service, Aiken Forestry Sciences Lab
705 Spear St PO Box 968, Burlington VT 05402
Abstract
Water resource experts predict that mankind is near to utilizing ALL the
world's fresh water resources just to feed and 'water' the growing human population.
So in the future we will have to reach a suitable compromise between water use and
yield in agriculture. The theme of my presentation will be to talk about how we measure
drought performance as an aid to understanding mechanisms of drought resistance.
This is a necessary prelude to understanding how we might maximize water use
efficiency in crops. Understanding the basic biology will make it easier to see the path
we need to follow in agriculture.
135
Estimation of Actual Evapotranspiration over a Greenhouse Tomato Crop
by using the Penman-Monteith Equation*
Hector Valdez and S. O. Ortega-Farias
Centro de Investigación y Transferencia en Riego y Agroclimatoligía (CITRA)
Depto de Facultad de Ciencia Agrarias
Universidad de Talca.
Casilla 747-Talca, Chile
E-mail = [email protected]
Abstract
A study was performed to evaluate Penman-Montieth (FAO-PM) model to
calculate actual evapotranspiration (ETactual) over a greenhouse tomato crop at the
Panguilemo Experimental Station (PES), which is located in Talca, Maule Region of
Chile. In this research an eddy correlation system and an automatic meteorological
station were installed in order to measure ETactual and climatic variables, respectively.
Results indicated that there was a high correlation between measured and estimated
values of ETactual with an overall standard error of estimate (SEE) of 40 W m-2 for
cloudy and cloudless conditions. Major disagreements between measured and
estimated values were observed at the end of the growth period and were associated
with an overestimation of surface resistance.
*Investigación financiada por el proyecto FONDECYT N° 1970309
Effect of Irrigation on Fruit Yield in Cucumis Sativus L.
Vasudevan, N. Selvaraj
Department of Botany
Periyar E.V.R. College (Autonomous)
Tiruchirappalli – 620 023
Tamilnadu, India
S. Kasthuri Rengan and A. Ganapathi
Department of Biotechnology
Bharathidasan University
Tiruchirappalli 620 024, Tamilnadu, India
[email protected], Tel: 04312407086, Fax: 0431-2407045
Astract
In the present study the effect of irrigation on fruit yield of three important
cucumber (Cucumis sativus L.) cultivars like Poinsett 76, Greenlong and Endeavor
were studied. Among the different types of irrigation methods tested, bed field type was
more effective than spillage and drop methods. Two day regular interval of irrigation
was more essential for Greenlong and 3-day interval required for Poinsett 76 and
Endeavor. The effect of gap between plants was also studied in three cultivars. In all the
three cultivars two feet gap was more essential to in order to get higher yield. The fruit
yield was higher in Greenlong when compared to Poinsett 76 and Endeavor.
136
Water and Nitrogen Management in Drip Irrigation Processing Tomato.
Vázquez , N., Pardo, A. and Suso, Mª.L.
Centro de Investigación y Desarrollo Agrario
(C.I.D.A.), NA-134, km 88, 26071 La Rioja.
Spain
Quemada, M.
Departamento de Producción Vegetal:
Fitotecnia. E.T.S. Ingenieros Agrónomos.
Universidad Politécnica. 28040. Madrid.
Spain
Abstract
The objective of this study was to optimise water use and to reduce nitrate
leaching in tomato (Lycopersicon sculentum Mill) cropped with drip irrigation and
plastic mulch. Two field experiments were conducted in Valdegon (La Rioja). Over a
fine clayey soil, in which tomato, cv. Brigade, was cultivated under four different
irrigation strategies: large dose at planting followed by daily irrigation equal to the ETc
during the growth period (T1R1), large dose at planting followed by daily irrigation
equal to the 80% ETc (T1R2), reduced dose and high frequency at planting followed by
high frequency during the growth period (T2R3 if water applied was 100% ETc, and
T2R2 if it was 80% ETc). To evaluate nitrate leached to 1 m. depth, the drainage
volume was multiplied by the nitrate concentration of the soil solution at that depth.
Drainage was calculated by weekly measuring the water content of the soil profile and
applying the water balance equation. The soil solution at 1 m. depth was extracted by
porous ceramic cups and was analysed for nitrate. Drainage and nitrate leaching were
evaluated for two different crop periods: planting and growth. During the growth
period, cumulative drainage accounted for more than 20% of total water applied for
T1R1, near zero for T2R2 and intermediate values for the other treatments. Nitrate
leaching was closely related to water losses. In 2001 most of the nitrate losses occurred
during the planting period and they were spread over both periods in 2002. Increasing
frequency irrigation allowed to reduce water application, maintaining yield and
optimising water and nitrogen use.
137
Soil Evaporation Processes and their Relation with Thermoconductivity for
a better Estimate of Evapotranspiration from Row Crops
F. Ventura and M. Bittelli
Dipartimento di Scienze e Tecnologie
Agroambientali, v. Fanin 44, 40127 Bologna,
ITALY
R.L. Snyder
Department of Land, Air and Water
Resources, 125 Hoagland Hall, Davis, CA
95616-8627, USA
Abstract
Accurate estimates of crop evapotranspiration (ETc), which quantify the total
water used by the crop, are needed to optimize irrigation scheduling for horticultural
crops and to minimize water loss and degradation. Water use assessment is difficult in
vegetable crops because of high soil evaporation during early crop growth. In order to
have a better ETc estimate a specific model for row crops was developed (Ventura et al.,
2001). The model separates plant transpiration from between row evaporation using
only reference evapotranspiration (ETo) as daily input parameter. Soil evaporation is a
two-stage process (Ritchie, 1972; Idso et al., 1974; Stroosnijder, 1987). During stage-1,
the evaporation rate depends only on the energy available to vaporize water.
Eventually, the soil dries to stage-2 and the evaporation rate is limited by soil hydraulic
properties. The hydraulic properties are characterized by a single parameter, called the
β-factor, which is used to determine the end of stage-1 evaporation and the evaporation
rate during stage-2. Currently, difficult experimental measurement (e.g., eddy
covariance or Bowen ratio) is required to determine β for each soil. It would be useful
to establish a functional relationship between the β-factor and one or more soil
characteristics that are easier to evaluate. The β-factor is unrelated to soil texture
(Ventura et al., 2001) or infiltration rate (Boesten and Stroosnijder, 1986; Snyder et al.,
2000). In this paper we will describe simple method to determine the β-factor, based on
soil moisture gravimetric measurements that can be conducted by extension advisors or
farmers. Moreover we believe that the soil evaporation during stage-2 is related to
thermal conductivity of soil, which would limit the transfer of energy from the surface
to the depth in the soil where most of the evaporation is occurring. In order to find
relationships between the β-factor and thermal conductivity during the β-factor
gravimetric measurements we will use soil heat flux plates and thermocouples to
determine the thermal conductivity and the soil heat flux density. This procedure will
provide a new method to determine thermal conductivity (CT) for use in calculating soil
heat flux without the need to measure or estimate soil water content and the verification
of the existence of a relationship between β and CT.
138
Determination of the Momentary Water Uptake Rate and its Oscillations
by Spectral Analysis of Frequent Weight Measurements of a Growing
Container
Rony Wallach
Department of Soil and Water Sci.
Faculty of Agricultural Food and
Environmental Quality Sciences
The Hebrew University of Jerusalem
P.O. Box 12, Rehovot 76100, Israel
Michael Raviv
Agricultural Research Organization
Dept. of Ornamental Horticulture
Newe Ya’ar Research Center
P.O. Box 1021 Ramat Yishay 30095
Israel
Abstract
Root systems of container-grown plants are confined to a limited volume of
medium, characterized by low buffering capacity for water, while potential
transpiration rates may be very high under greenhouse conditions. Coupled with the
low unsaturated hydraulic conductivities of many porous media, water delivery should
closely fit its uptake rate by plants. Optimizing water supply requires basic
understanding of the momentary water uptake rate. Water status is usually determined
by direct and indirect measurements (container weight, sap flow, TDR, water tension
etc.). These measurements are usually repeated very often (seconds, minutes, hours)
and the output contains noises. Water uptake rate is calculated as the derivative of the
measured data, which significantly amplified the noise. The noise can be filtered out by
smoothing. The efficiency of the smoothing methods is measured by its ability to
completely eliminate the noise. The question is what is the importance of this noise,
namely, does the filtered noise is "white" and associated with random measurements
errors or do we filtered out "colored" noise that contain information on the effect of
physiological and environmental processes on water uptake. This question can be
answered using spectral analysis of the measured data. Oscillations at different
frequencies and amplitudes in water uptake rate were obtained when the differences
between the measured and smoothed data (residual) were analyzed by spectral analysis
methods. The relationships between the smoothed water uptake rate and the oscillations
amplitudes and frequencies on one hand and the environmental and physiological
factors on the other hand were identified and examined. The effect of the growing
media properties on these oscillations are provided as well. This presentation includes
data measured in a semi-commercial greenhouse as opposed to other studies that were
conducted in growth chambers in which most variables can be kept stable.
139
Gravel Vertical Mulching, in Drip Irrigated Orchards, as a Means of
Improving Water Use Productivity
Yanni. S. F., M. N. Nimah, I. Bashour, M.R. Darwish
Faculty of Agricultural and Food Sciences
American University of Beirut, Lebanon
Keywords: gravel Mulch, vertical irrigation, evapotranspiration, water productivity
Abstract
Drip irrigation, even though may be considered the most efficient irrigation
method today, still allows relatively high evaporation from the saturated zone that
develops under the emitter. In low infiltration soils, initial lateral water movement can
take a long time, exposing surface water to high evaporation; a vertical gravel tube,
installed in the soil beneath the emitter, will induce vertical water infiltration keeping
the actual water surface deeper in the soil profile. The objective of this research was to
study the effect of gravel vertical mulching (GVM) on root zone water distribution, the
potential for water saving as well as the economic feasibility of utilizing GVM in
orchards.
A field experiment was conducted, at the Agricultural Education and Research
Center (AREC), to meet the stated objective. Two factors were studied; (A) Level of
irrigation studied in three levels (100, 70, and 40%) of actual evapotranspiration and
(B) Gravel in two levels (gravel and no-gravel). The 2 X 3 treatments were randomized
over nine trees in three replicates, and soil moisture content was measured at 1, 7, and
14 days after each of two irrigation events. Measurements were taken at 3 distances and
4 depths from each dripper. The results indicated that the irrigation level has a
significant effect on water storage at deeper soil layers, whereas the gravel is effective in
increasing soil water content at the 20-50cm layer and becomes insignificant at deeper
layers. Over time, as the soil is drying up, the significance of the gravel factor increases.
Specifically, talking about the root zone profile as a whole, the 40%, irrigation level,
plots had significantly higher water content than the 70 and the 100% and the Graveled
plots had higher water content than the Non-Graveled ones.
140