Download PhD Dissertation: EFFECT OF LOW SOIL

WARSAW AGRICULTURAL UNIVERSITY
(SGGW)
SHEK GIBRILL SESAY
EFFECT OF LOW SOIL MOISTURE ON SOME PHYSIOLOGICAL
PARAMETERS IN Amaranthus cruentus and Chenopodium quinoa
This study was carried out in the
Department of Plant Physiology,
under the supervision of dr. hab.
Tadeusz Loboda.
This work is in part fulfilment for
the award of the doctorate degree
in the Dept. of Plant Physiology.
WARSAW 1997
TABLE OF CONTENTS
Dedication
(I)
Acknowledgement
(II)
Chapter
Page numbers
Introduction
1
I.
Literature review
3
II.
Methodology
28
III.
Results
38
IV.
Discussion
66
Bibliography
75
Appendix
144
(I)
This work is dedicated to my late father Alhaji Sheku Sesay who died in 1993,
while I was still researching.
(II)
ACKNOWLEDGEMENT
I wish to thank my supervisor dr. hab.Tadeusz Loboda, for the constructive
criticism, wise counseling and tremendous effort he generally expended in
realizing this work..
I further wish to sincerely thank the entire staff of the Plant Physiology
Department, of the Faculty of Agriculture, with high consideration due the head
Prof. dr. hab. Emil Nalborczyk, for conducting the department in such a way as
to enable this research, dr. Stefan Pietkiewicz, mgr Marzanna Gontarczyk, dr.
Danuta Choluj and mgr Barbara Wawrzonowska.
I am also forever grateful to my friend mgr Bogna Cyprys and her family, she
had been a constant source of consolation. I also wish to thank mgr James
Ofwona for his help in typing the completed work.
I am also appreciative of my daughters’ efforts, Tity Gibrill-Sesay for waiting
patiently during the research and Kadi Gibrill-Sesay, in helping me irrigate the
plants.I also appreciative the efforts of my mother and other relatives who were
devoid of my company and support during the research years.
many thanks to my Sierra Leonean colleagues for mutual support when one was
in need of one.
INTRODUCTION
The ancient crops of Amaranthus cruentus (amaranth) and Chenopodium quinoa (quinoa)
have in the recent past captivated the interest of researchers and the general public at large. As
a result of this they have been referred to as promising “rediscovered” crops. The cultivation
of these crops has far reaching historical background. Tapia (1982) reported that the
cultivation of quinoa in the Andean highlands can be traced to 3000 BC. The high protein
content of quinoa effectively recommended it as a meaningful alternative to the Andeans who
lacked protein source such as meat and dairy products. Digging-up history holds that
amaranth had been under cultivation in places around present-day Colorado, Mexico and
some regions of Tamaulipus already since 4000 BC.
Survival of these crops to this day, after strong impact exerted by Christianity to halt their
propagation is associated with several factors. In the case of amaranth its ornamental value
was first recognized by the very religious groups that earlier decleared its propagation
punishable. Later both crops were able to survive as a result of increasing interest in the
cultivation of the pseudocereals. The increased interest was the result of a whole host of
advantages which range from nutritional to industrial ones.
Currently elevated levels of essential amino acids have been discovered in these
pseudocereals. Lysine is usually found in comparatively higher levels than in conventional
cereal crops like maize, rice and wheat. An admixture of the two types of crops in the human
diet, will lead to a balance of essential amino acids.
From the point of view of pharmacy it is noteworthy that both the inhibitors of LDLcholesterol synthesis and a set of squalene have also been discovered in amaranth.
Considering plant oils, squalene content of amaranth oil is high. About 1/400 of the seed
weight or 5-8% of the seed oil (Lyon and Becker 1987).
Most plants from tropical to temperate zones do undergo some kind of moisture stress at
some stage of their development. Low moisture strain in plants is an effect caused by the
environmental stress of a decrease in the water level necessary for the plant to carry out its
normal metabolism. Plant response can take various forms and the results are equally diverse
including tolerance, susceptibility and prevention (Levitt 1972, 1980).
It is always the endeavour of research to reasonably quantify the responses, with a view of
recommending appropriate agronomic practices and otherwise, necessary in enabling the plant
to cope with the stress. The possible responses are from the sub-cellular level including
change in the conformity of membrane-bound electron carriers or enzymes, implicated in
various metabolic processes, to the whole plant level. Growth analysis, gaseous exchange
measurement, radioactive tracers and nutrient composition analysis have insofar been used to
follow the development of the pseudocereals since germination until final completion of the
life cycle.
This study aims at comparing A. cruentus with C. quinoa in vegetative and generative
crops in both the stressed and the unstressed combinations cultivated under Polish
environmental conditions.
LITERATURE REVIEW
1.1 GEOGRAPHIC DISTRIBUTION OF THE CROPS
Amaranth can grow satisfactorily from sea level to above 3000 m, but only A. caudatus is
known to thrive at altitudes of 3000 m in the Andean region and the Himalayas. Amaranth has
been grown in geographic latitudes around 30O N and even in higher latitudes. As it is not
frost tolerant, its production is limited to summer months in northern latitudes. However the
requirement for a killing frost to facilitate harvest may provide production advantages for
northern latitudes (Johnson et al. 1990). The crop grows best when the daily mean maximum
temperature is at least 21O C. Various accessions have shown optimal germination at
temperatures varying between 16O C and 35O C. The rate of emergence is increased at the
upper end of the range. The growth of the plant ceases at 8O C and the plants are injured
below 4O C. However A. caudatus being native to the Andes and high Himalayas is more
resistant to chilling than A. hypochondriacus and A. cruentus. Weil et al. (1987) suggested
that field emergence may be satisfactory with soil temperature between 18.5 and 24O C.
Carmen (1984) stated that quinoa is currently grown for its grain in the following South
American countries: Argentina (North), Chile (Central and North), Bolivia, Peru, Ecuador and
Colombia. According to Risi and Galwey (1984) quinoa is cultivated from sea level in SouthCentral Chile (40oS) to Southern Colombia (2oN) and from sea level to an altitude of about
3800 m. Indeed it is on the basis of this statement that a germplasm collection containing 294
accessions from this range of environment was screened for photoperiodic neutrality.
Probably some genotypes that are from sea level ecotypes of South-Central Chile may well
exhibit the characteristic of daylength neutrality.
Quinoa is cultivated at high altitudes in the Andes. Gandarillas (1968) described 17 races
based upon morphological characters, while Galwey (1989) and Tapia 1979 proposed four
main types based upon geographic location: the "valley" type, typical from 2000 to 4000 m in
elevation; the "Altiplano" type, typical of highland areas above 4000 m in elevation; the
"Salar" type of 4000 m but adapted to the high pH soils typical of the Atacama region; the
"Sea level" types found in the inner valleys of Bolivia. They also reported that Wilson’s
electrophoretic work has shown the "Sea level" type to be distinctly different from the other
highland quinoas.
1.2 USES
Notwithstanding the fact that amaranth is a pseudocereal it can be used in many ways
similar to our better-known cereals. The following major characteristics have been found
recommending in the uses of amaranth. First it has been found to have a protein level ranging
between 13 and 19%. Equally important is the relatively high lipid content compared with
other cereals (Bressani, 1990). The micro-crystalline starch granules have been found to be
unique. Also squalene and tocotrienol levels have been found to be very high. Amaranth has
also got the ability to be popped and used in a variety of confections and bread.
Regarding industrial applications, these include uses of amaranth biomass for energy and
development of unique applications of grain components. The tiny starch granules (1-3
microns) may be used as a talc replacement, an aerosol carrier for cosmetics or perhaps in
biodegradable plastics (Saunders and Becker 1984). Approximately 7 % of the seed oil
consists of a compound called squalene. This is an important ingredient in skin cosmetics and
Preparation H as well as disc lubricants. Squalene is currently imported from Scandinavia and
the Far East. It is obtained from whale and shark oils. The market for squalene is estimated to
be over 60000 lbs / year (at $26.00 / lb-Lehmann 1990).
The potential impact of amaranth on human health is another area of increasing interest.
Amaranth oils contain over 0.1 % tocotrienols, a class of vitamin E compounds which have
been found to inhibit cholesterol (especially low density lipoprotein-LDL, the "bad"
cholesterol) synthesis in laboratory animals. This content though, seemingly small, may be
greater than that of many of our other common crops (Lehmann 1990). According to
postulates of University of Illinois, tocotrienols are superior in the treatment of high serum
cholesterol levels compared with corn oil placebo. Results of the study have shown that men
and women with high serum cholesterol levels showed 20-31% decline in total serum
cholesterol, and 28% decline in LDL when treated with 200mg of tocotrienols as compared
with corn oil placebo controls (Science News 139:268, 4 / 91). The mechanisms for control of
blood cholesterol via the use of cholesterol inhibitors (eg. tocotrienols) is distinct from the
role of dietary fibres (eg. oat bran), since small quantities of inhibitors in the bloodstream
could have an impact on serum cholesterol.
The species most widely used as vegetables are probably A. cruentus, A. dubius, and A.
tricolor (Makus 1990). Amaranth greens (A. tricolor) contain about 28 % of proteins, 3.5 %
lipids, 7 % fiber and 43 % carbohydrates, and respectable amounts of vitamins A and C
(Makus 1990). In general, cooking or processing has an impact on the quality of green
vegetables. Anti-nutritional compounds such as alkaloids, betacyanins, oxalic acid, and
nitrates can be found in amaranth leafy material but this is also true for other leafy vegetables.
Amaranth is a common vegetable in Africa and parts of Asia, while in the United States the
markets are restricted to regions of the South and immigrant communities in large cities.
Although amaranth grain has been used in traditional foods in several cultures (Laidig
1981), it is not widely known to American consumers. This, however, is changing. Lehmann
et al. (1990) estimated United States production of amaranth to be from 1.3-1.8 million
pounds in 1988, on less than 5000 acres nationwide. There are several entrepreneurial groups
in the US who have worked hard to develop markets and production stream for amaranth. The
Amaranth Institute (Bricelyn, MN), a consortium of US growers, marketers, and researchers
meets ones a year to share information and review latest advancements for the crop. This
network has been important in the development of the crop to date and is likely to be
important in the future.
Amaranth is higher priced than most commodity grains (prices have been 40-50 cents / lb
to growers over the past several years), and so it is often included as an additive to a product
rather than as the major ingredient. Teutonico and Knorr (1985) and Breene (1990) detailed a
range of amaranth products: baking mixes; flours; breakfast cereals; snack foods; backed
goods; canned products; pasta; sprouts; milled popped and extruded products; drinks infant
formula; and animal feeds which are or can be made from amaranth. Several of these have
been moderately successful and entered national markets and can often be found in health
food sections of food outlets.
Lehmann (1990) outlined the factors of government support, price research, dependability
of supply, pest control, and consumer familiarity to be important to the succesful
commercialization of amaranth in the 1990s.
Amaranth is a vigorous, fast growing plant which produces abundant dry matter per unit
time and area. This, in addition to its high protein content makes it a candidate for a forage
crop; the primary role that amaranth could have as a forage is as a late-planted summer forage
for northern climates or for drier areas. It is rather unlikely that amaranth could play the same
role as alfalfa, with its perennial habit and high protein values. Amaranth forage and protein
yield have been shown to be competitive with other summer annuals such as sorghum / sudan
grasses. Amaranth has been known to ensile well, although high moisture content will require
wilting (Stordahl, Unpublished).
Since amaranth is capable of producing floral buds from any leaf axil, it is a plant which is
a candidate for a multiple-use crop, especially for farming systems which utilize animals. In
environments which lack green fodder, but where farmers also require a cash crop or grain
crop, amaranth plants could be cut for forage at an early stage, before significant floral
growth. The daylength response in many lines causes flowering to occur early enough to
produce a grain crop in addition to the forage crop. In some environments, this practice could
aid in reducing plant height for ease of harvest, or lodging resistance.
Quinoa may be used either as a whole grain or ground into a flour. As a whole grain it may
be incorporated into soups or cooked and served in a manner similar to rice. Its main use
being in soups. Quinoa and Chenopodium pallidicaul (canihua) grains have no gluten and so
they cannot be used alone for bread-making. Quinoa flour can be mixed with wheat flour in
the preparation of bread and noodles, the proportion of quinoa flour varying between ten and
forty per cent (Luna De la Fuente 1957). Weber (1978) stated that noodles have been made
using 40 % quinoa flour without adversely affecting the appearance of other characteristics. It
should be noted that quinoa was used in a composite flour blend for Bolivia (Bean 1981; Bean
et al. 1982). Levels of 5 and 10 % quinoa in a wheat flour-quinoa blend caused a decrease in
loaf volume (Bean 1981). Potassium bromate added at 20 or 40mol mol-1 counteracted this
volume decrease and produced bread similar to wheat bread with no dough additives. A
number of quinoa recipes for cookies, chowder, croquettes and casseroles, have recently
become available (Gorad 1986). Flour milled from germinated quinoa has also been used to
reduce the viscosity of starchy foods. Supplementation with germinated quinoa flour may
help to increase the palatability and the effective caloric density of food used for weaning
children (Atwell et al. 1988). Flakes, similar to corn flakes, have also been prepared from
quinoa (Tapia et al. 1979).
Corn grits-quinoa blends have been extruded successfully (Coulter 1989). Quinoa was
blended with corn grits at levels of 10, 20 and 30 % and extruded under various conditions.
The most acceptable products, he continued, were obtained at a 15 % initial moisture content
and a 3:1 compression ratio of the extruder screw. Quinoa addition produced products which
were higher in protein, fiber, ash and some amino acids than 100 % corn grits products. The
products containing quinoa had a greater nitrogen solubility than the products containing only
corn grits. Density, expansion and shear strength were lower for products containing greater
levels of quinoa. Quinoa addition also produced a darker, less yellow product than corn grits
alone.
Quinoa flour has given good results in feeding trials with chickens, pigs and ruminants.
Stacks, chaff, gleanings, and bran are used to feed ruminants. The saponins obtained as a byproduct in the processing of quinoa can be utilized in the preparation of products for
photography, cosmetics (shampoo), and the pharmaceutical industry (synthetic hormones)
(Tapia et al 1979).
1.3 BOTANICAL CHARACTERISTICS
1.3.1 Amaranthus cruentus aspect of the study.
TAXONOMY
This dicotylidonous plant is classified under the Amaranthaceae family and belongs to the
genus Amaranthus (Szafer 1949, Hegi 1959, 1979). The family Amaranthaceae includes other
genera like Achyranthes, Alternauthera and Celosia (Flora Europaea, Anonymous 1964). The
genus Amaranthus is one of 65 genera in the family Amaranthaceae (Thames and Hudson
1966). The plants, in this family extensive, are mostly found in the tropical and sub-tropical
zones of America and Africa (Thames and Hudson 1966; Hegi 1959; 1979; Nowak 1972).
The family Amaranthaceae is a close relative of Chenopodaceae. Thames and Hudson (1966)
particularly pointed out the similarity in the floral structure. They also noted the difference in
the floral colour due to the coloured flowers of members of the Amaranthaceae family. The
colour of the flowers enables insect-pollination. It is not easy to distinguish the two families
in a natural way (Szafer 1919).
Willis (1973) stated that about 60 species make up the genus Amaranthus. However most
of them are weeds. Weber (1990) identified A. spinosis, A. tuberculatus, A. retroflexus and A.
rudis as weedy species. Domanska (1990) identified A. retroflexus as one of the most difficult
to control. It is regarded as occupying third place in the hierarchy, in detrimentality to proper
growth of cultivated crops. However the weedy species have some traits that render them
useful. Brenner (1990) highlighted A. powellii A. bouchonii as weedy species involved in
breeding for controlling shattering of seeds in mature plants.
There are also cultivated species in this family. A. cruentus, the species in the investigation
at hand, has in the recent past proved to be very promising to researchers. This is largely due
to the fact that unlike other species like A. tricolor, this species can be useful both as a
vegetable as well as a grain crop.
Further down in taxonomic grouping, the species under investigation is known as
Montana-3 (MT-3) developed at Montana in the United States and released in March 1988.
The MT-3 grain amaranth is itself a selection from RRC-1041 developed by the New Crops
Department of the Rodale Research Center (RRC) at Kutztown, PA, from a single plant
selection RRC-78S-1015 (Kauffman 1981). The line MT-3 has been registered under the
name Amont (Montana Amaranthus).
MORPHOLOGY
The family Amaranthaceae has got different forms of aerial growth. There are members of
this family that are branched while others are devoid of branches. Other members of the
family are creeping while others are upright in growth. There are also colour differences
noted. The leaves and stems display colours ranging from red to green.
The colour of the seeds also differ among the members. There are white, yellow, brown to
totally black seeds (Amaranth-Information, Annonymous 1989). The grain types have white
seeds while the vegetable types (as well as those used to extract red dye) usually are dark
seeded. Amaranth seeds are very small; 1000-3000 seeds per gram are common. Although
selections have been made over the years for pale seeds (the wild species all have black
seeds), large inflorescence, and more seeds per plant, there has apparently been little selection
for large seed size (NAS 1984).
The plants are mostly monocious but sometimes dioecious. The members of this family are
mostly annuals and seldom perennials. The leaf arrangement is either opposite or alternate.
The leaves can be with or without a leaf stalk. They are noted for lack of leaf bract. The
members have singly occurring inflorescence. The flowers exhibit monoecism or dioecism.
The ovaries are hypogynous and very seldom perigynous. The flowers are usually in a thick
cluster of ear (Hegi 1959, 1979; McGregor 1970; Malean and Rivimey-Cook 1951).
The grain amaranth species belong to the genus Amaranthus and are characterized by
monoecious compound inflorescence and five merous flowers with circumscissile utricles.
The basic units of the inflorescence are little dichasial cymes, usually called glomerules, each
ordinarily consisting of an initial staminate flower and an indefinite number of female
flowers. The glomerules are crowded on a leafless axis to form complex inflorescence,
technically thyres, which are generally called spikes. In all the grain species, each flower is
subtended by a sharp-pointed bract. The perianth consists of five free "tepels" the male
flowers characteristically have five stamens, the female a single circumscissle utricle.
The main axis of the inflorescence is usually branched. The length and number of these
branches and their angle with the main axis determine the shape of the inflorescence. The
cluster of individual flowers develop along this axis in an alternate fashion. The first flower is
terminal on the branch and at its base two branches develop the second and the third flowers.
Each of these flowers in turn is terminal and at its base develop the next two flowers. This
process continues until all the available space is occupied. Development is usually very
symmetrical up to the third or fourth series of flowers. At this time the setting of the first seed
usually shows down growth and upsets the symmetry. Unpollinated clusters may develop an
exceptionally large number of flowers. The monoecious species, exhibit two types of
arrangements of the staminate and pistillate flowers. These types are important because of
their different breeding behaviour. In the first type, the first flower of each flower cluster is a
staminate flower and all the secondary ones are pistillate. There is only one staminate flower,
in each flower cluster of the inflorescence and this abscesses soon shedding pollen. All
species except A. spinosus, belong to this group. In the second type, all the flowers develop
only in the axis of the branches and at the base of the terminal inflorescence, while the
clusters of staminate flowers are born terminally on the main axis and lateral branches. The
species A. spinosus, belongs to this type (cited by Josi and Rana 1991).
A. cruentus L. has leaves with long leaf stalks. They are rhomboid to egg-like in shape,
both ends are drawn to sharp bony tips. The flowers are collected in thick clusters. Leafless
clusters form sedentary lids on the tips of stems, sometimes bottom clusters at the base have
leaves (Amaranth information, Annonymous 1989).
1.3.2 Chenopodium quinoa aspect of study
TAXONOMY
The plant belongs to the Glasswort family, Chenopodiaceae. Wilson (1990) stated that
over 120 species have been found within the genus Chenopodium. Chenopodium quinoa is
not the only chenopod of importance to mankind, a very similar plant huauzontle (C.
berlandieri subsp. nuttalliae), is cultivated in Mexico as a vegetable and for grain, and a lowgrowing species, canihua (C. pallidicaule), is grown for forage and grain on the Altiplano
around lake Titicaca. In the Himalayas, plants classified as C. album are cultivated for grain
(Partap and Kapoor 1984). The adaptability to cold, dry climates, seed processing similarity to
rice and excellent nutritional qualities make quinoa a crop of considerable value to highland
areas around the world which are currently limited as far as crop diversity and nutritional
value are concerned. Development of the other Chenopodium species in the United States
(Wilson 1981), the Himalayas (Partao and Kapoor 1985), Mexico (Risi and Galway 1989) and
Denmark (Renfrew 1973) illustrates a diverse appreciation for this genus. Even the weedy
relatives, C. album and C. berlanderii in the United States and around the world have been
utilized as food during times of starvation.
MORPHOLOGY
The plant is a summer annual leaf-rich herb. It varies in height from 0.7 to 3.0 m and has
an upright stem that may be branched or unbranched. It is stout between 0.5-2.5 cm in
diameter. It may have grooves or simply smooth, oval to spherical. It bears alternate highly
polymorphic leaves. The fruit they produce has a pale yellowish colour with an occasional
tinge of magenta pigment. The grain is conical, cylindrical, or ellipsoidal in shape and it
varies in diameter from 1.8-2.6 mm. The weight of 1000 seeds (TSW) is 3.0 g (KVL O188
variety). The grain is protected by a perianth consisting of loosely adhering cells, which can
easily be removed by washing, a pericarp and two seed coat layers. It is the seed coat that
contains the bitter saponins. A thin episperm covers the curved embryo (Coulter and Lorenz
1990). The flowers are usually monoecious cleistogamous, inflorescence 20-30 cm long.
Cross pollination is between 2-9%, which means inbreeding is predominant.
1.4 GENETICS AND BREEDING
1.4.1 Amaranthus cruentus aspect of study
The majority of plant characters is polygenically inherited with relatively large numbers of
genes exerting greater or lesser effect. In the Amaranthus species the environment modifies
the genes in the expression of most of the characters. Field evaluation screening and study of
the genetic variation for a set of morpho-agronomic attributes showed a wide range of
variation in grain amaranth (cited by Joshi and Rana 1991). Among the characters studied,
thousand seed weight, protein percentage, seed yield, plant height and inflorescence length
had shown high genotypic coefficient of variation, high heritability and high genetic
advancement indicating that these are more important traits for selection or breeding (Joshi
1986).
Genetic variation in landraces was studied by Jain (1985) using qualitative markers,
quantitative traits as well as allozyme variation. The New World collection varied in the
amounts of genetic variation between regions and possibly between species. Most landraces
seem to be highly homozygous and carry a significant amount of variation for quantitative
traits such as plant height, branching, flowering time, head length and harvest index.
Accessions from India rather suprisingly, showed no or little allozyme variation within and
among populations, but seemed to be highly variable from a morphological point of view.
Ten landrace populations from two states of India were evaluated in the greenhouse by
Vaidya (1984) for genetic variation of qualitative characters. The qualitative characters
studied were: seedling colour, leaf margin colour, leaf texture, leaf margin hairiness, leaf
marker and inflorescence colour. These characters segregated in several families of the
populations. Seedling colour difference (red Vs green) was simply inherited while the ‘V’
mark leaf marker was controlled by two epistatic genes.
1.4.2 Chenopodium quinoa aspect of study
Genetic make-up is very important in screening for particular characteristics, selection, or
routine field evaluation. In all these cases the allowance for genetic interaction in the
expression of character traits should be unlimited. Proof of this attribute in C. quinoa is
manifested in results of cytological studies by Crawford (1973) who identified diploid and
tetraploid species. Furthermore hexaploid species of C. album that are smooth-fruited have
been identified by (Cole 1962; Keener 1970; Uotila 1978). The fact that these smooth-fruited
C. album complex appears to be essentially European in origin was expressed (Wahl 1952,
1953; Aellen 1960).
The species of the genus Chenopodium are generally self-compatible and anemophilous.
Flowers are small and often clustered into dense bracteate glomerules. These makes artificial
hybridization, which often involves emasculation and cross-pollination inapplicable. However
male-sterile strains of the alveolate-fruited domesticate of C. quinoa developed by Simmonds
(1971), indicated that anther abortion is a simple recessive characteristic that can be inherited
cytoplasmically. Another hybridization program involved the use of egg parents with no
history of male-sterility in investigations, by Wilson (1980), on photoperiodic response.
A screening study by Risi and Galwey (1988) involving 294 accessions of quinoa
evaluated at Cambridge, England, registered the rich admixture of genetic make-up in the
expression of character traits. These researchers were screening for a break crop for arable
agriculture in temperate latitudes. The ideotype of short, unbranched, early maturing plant
with a compact inflorescence and a high harvest index, large light-coloured seed with a low
saponin content, were postulated for in chilean accessions.
1.5 CHEMICAL COMPOSITION
1.5.1 Amaranthus cruentus aspect of study.
Saunders and Becker (1983) compared results of nutrient composition analysis and other
feeding values of selected leafy vegetables to those of amaranth. The vegetables involved
were Spinach, Basella and Chard. Amaranth’s 36 Kilo calories of energy per 100g of edible
portion was the highest compared with those of the other vegetables. The dry matter,
carbohydrates, protein and ash contents of 13.1, 6.5, 3.5 and 2.6 g/100g respectively of edible
portion of amaranth were also found to be the highest. They also reported the results of
phosphorus, potassium, calcium, chlorophyll, vitamin C and carotene as 67, 411, 267, 150,
105, and 10.1 mg/100g respectively for amaranth. It should be noted that, except for
potassium and carotene, the afore-mentioned values of amaranth were the highest compared
with the other vegetables. It should be further noted that the values of potassium and carotene
although not the highest were however not very disimilar to the highest.
Bressani et al. (1987a) reported the mineral content of four grain amaranth i.e. A. caudatus,
A. hybrydus, A. cruentus and A. hypochondriacus in mg/g dry weight basis (d.w.b). The
values of phosphorus, potassium, calcium, magnesium, sodium, iron, copper, manganese and
zinc they reported as 556, 525, 242, 344, 25, 26, 1.69, 3.4 and 4.2 respectively for A. cruentus.
It should be observed that except for iron, A. cruentus was found to have higher or
comparable values with the other species.
The elevated crude protein level of both vegetable and grain amaranth with respect to the
level considered adequate is among the reasons that amaranth has recently been decleared an
under exploited crop with promising economic value by the National Academy of Sciences in
the United States (NAS, 1975, 1984).
Food Technology of April (1985) reported tabulated results of nutrient elements. The
vegetable amaranth and the grain amaranth had 20.9-33.0% and 13.2-17.6% CP respectively.
These are elevated with respect to the 1.5% N (9.4% CP) level considered adequate in table 8.
As a whole amaranth compares favourably
to other cultivated crops. According to
Amaranth Brochure (1991) the crude protein content of Amaranthus species is about 16% of
DM. This compares favourably to the values of crops like wheat 13.3 %, corn 7.8 %, rice 7.6
% and oat 14.2 % reported by the same publication.
The amino acid composition of amaranth is very complex and often high in essential amino
acids for the normal human diet and forage production (Tayler 1981; Lehman, 1989;
Czamieliwa, 1989; Nalborczyk, 1991).
Recent CIMMYT progress in producing quality protein maize (QPM) suggests that the
protein level of corn can also be modified to produce superior human and animal foods.
However, if one considers that various amaranth/cereal blends may accomplish the same goal,
much more concern is laid on the improvement arguement. For example Morale et al. (1988)
proposed that if toasted amaranth is blended in a 1 : 8 ratio, it could provide most of the
protein and fat needs of young children. According to a Rodale press report RRC 11/87
(1987), it can be deduced that using a mixture of a few grams of amaranth and cereal is
enough to satisfy the FAO/WHO daily recommendation of 2.94g amino acid /100g of grain
for leucine. Leucine is the limiting essential amino acid in amaranth. A similar mixture can be
used to satisfy the recommendation for methionine/cystine reported in the same issue of RRC
11/87. Simply this is a less expensive way to meet nutrient level requirements than trying to
raise the 0.19-0.265g amino acid /100g of corn as suggested by CIMMYT.
According to Saunders and Becker (1983) A. cruentus had the highest value 17.8 %CP
with a cross between A. cruentus and A. hypochondriacus as runner-up with a value of 17.4
%CP, while A. caudatus and A. hypochondriacus had values of 15.8 %CP and15.6 %CP
respectively.
In table 9 Tayler 1981; Lehman 1989; Czamieliwa 1989; Nalborczyk 1991, have shown
that Amaranthus cruentus might compare favourably to A. caudatus and A. hypochondriacus
as it has higher amounts of amino acids including essential exogenous ones like lysine, which
favours the possibility of synthesis of more different types of protein.
The fatty content percentage was reported by these workers as 7.8, 8.0, 8.1 and 6.1, the
crude fibre was reported as being 4.4, 4.1, 3.2 and 5.0, while the ash content was reported as
3.3, 3.0, 3.2 and 3.3 for A. cruentus, the cross between A. cruentus and A. hypochondriacus,
A. caudatus and A. hypochodriacus, respectively.
It is also important to note that the high protein content of amaranth is not at the expense of
the fat content. The following fat content in percentages has been reported : 7.2, 2.1, 4.4, 4.4,
5.1, 2.1, 1.8, 3.4 and 1.9 for amaranth, barley, corn, (dent) millet, oats, rice (with hulls), rye,
sorghum and wheat (hard) respectively (Garcia et al. 1987; National Academy of Science
1969).
1.5.2 Chenopodium quinoa aspect of study.
A breakdown of the nutritional value of C. quinoa is found on table 11. Some of the
micronutrients like Mn and Zn are found to have sub-optimal levels. Zinc, however had
optimal levels in C. quinoa white and C. pallidicaule. Iron and copper also investigated in the
cited study had optimal levels in all four species.
The comparison between mineral nutrient contents showed that in general some
antagonism does exist, between the macronutrients potassium and calcium. Leggett and Egli
(1980) highlighted this antagonism by stating that calcium and magnesium percentages
decrease concomitantly with increased potassium uptake. Apart from calcium that was
deficient in C. quinoa white and C. pallidicaule all the other macronutrients were considered
sufficient in all four species of Chenopodium in Table 10.
The nutritional value of quinoa has been known for a long time to be superior to traditional
cereals and is, in fact, superior to milk solids in feeding trials (White et al 1955). Protein
content ranges from 10 to 18% with a fats content of 4.1 to 8.1%. Starch, ash and crude fibre
average content is 60.1, 4.2 and 3.4%, respectively (De Bruin 1964, Ballon pers. commun.).
Table 10 compares four Chenopodium species.
Considering protein content it is noteworthy that C. quinoa has a few percentage points
higher than that of most cereal species, this is shown on Table 12. The protein has been found
to have a better balanced amino acid composition, having a higher proportion of lysine and
essential sulphur-bearing amino acids such as cystine and methionine. Notwithstanding the
high level of protein and mineral nutrients of quinoa, the presence of saponins is a major
setback in the use of the seeds for nutritional purposes.
Saponins are a class of bitter-tasting glycosides in which the aglycone portion (the
sapogenin) is a steroid alcohol. Saponins are soluble in water characteristically producing a
foam, hence their name (Blackmore and Tootill 1984). It is known that quinoa contains a
number of structurally diverse saponins including the aglycones, oleanolic acid and
hederagenin (Burnouf-Radosevich et al 1985). Mizui et al (1988) have identified six such
saponins from quinoa bran including those containing phytolaccagenic acid.
Quinoa can be classified according to its saponin concentration as either “Sweet” (saponin
free or having less than 0.11% saponin on a fresh weight basis) or “bitter” (containing more
than 0.11% saponins) (Koziol 1990b). Once saponin is removed, protein quality was
unaffected. Amino acid balance was virtually the same regardless of saponin content of the
seed (Burnouf-Radossevich et al, 1983). If C. quinoa is intended for human use, the saponins
must be removed before processing and/or cooking. Junge (1973) has described the use of
alkaline washing or dry scouring for this purpose whilst other workers have used rollermilling (Amaya-Farfan et al 1978) and abrasive dehulling (Reichert et al 1984, 1986b). Price
et al (1987) has described the effectiveness of these three methods of saponin removal by
exploiting the foaming, antifungal and haemolytic properties of saponins. It was also stated by
Galwey et al (1990) that genetic, agronomic and environmental factors as well as processing
can considerably affect saponin contents.
Accessions from Ilave market, Puno, which are fairly early maturing, and would therefore
be attractive sources of genes for low saponin content, have the disadvantage of small,
strongly pigmented seeds. On the other hand low saponin accessions with low saponin content
from the Andean valleys often have large white seeds but are tall and late maturing. The
authors however warned that some of the relationships between attributes are weak.
1.6 PHYSIOLOGY
1.6.1 Amaranthus cruentus aspect of the study.
The two species under investigation, belong to two different photosynthetic pathways. A.
cruentus belongs to the NAD-malic enzyme C4 pathway while C. quinoa belongs to the C3
pathway. The carbon dioxide fixation classified as C4 includes a wide range of plants.
Enlisted are warm-season grasses such as corn, sorghum sudangrass, sugarcane, millets,
bermudagrass and warm-season prairie grasses. Among dicotyledonous species identified in
this carbon fixation pathway are Amaranthus spp., and pigweed. This pathway incorporates
CO2 using phosphoenol pyruvate (PEP) carboxylase. The ATP which is produced in
photophosphorylation is used to convert pyruvate to PEP. The PEP, a three-carbon molecule,
is carboxylated to
three four-carbon acids (oxaloacetate, malate and aspartate). These
compounds are translocated to vascular sheath cells where fixated CO2 , by PEP carboxylase,
is released and further added to RuBP by ribulose bis-phosphate (RuBP) carboxylase/
oxygenase. Where the change to pyruvate, causes a carbon to be released that is further added
to RuBP by ribulose bis-phosphate (RuBP) carboxylase/ oxygenase.
The PEP carboxylase has greater affinity for CO2 than RuBP carboxylase/ oxygenase, so it
can operate more efficiently at low CO2 concentrations. Species with C4 fixation, generally
have higher photosynthetic rates than do C3 species, especially at high light intensities.
Among the reasons identified is the non-significance of photorespiration in C4 species which
is partly due to movement of the 4-carbon acids into the vascular sheath cells, hence elevating
the concentration of CO2. The elevated concentration of this substrate favours the RuBP
carboxylase reaction over the RuBP oxygenase. Equally important in the non-significance of
photorespiration is that loss of CO2 is prevented in the mesophyll by PEP (Goldsworthy
1970).
1.6.2 Chenopodium quinoa aspects of the study.
The C3 species include cool-season cereals and grasses like wheat, oats, barley, rice, rye,
bluegrass, fescue and bromegrass. Among dicots the list includes most temperate species like
C. quinoa, legumes, cotton, sugar beets, flax, tobacco, potatoes etc. The CO2 fixation portion
of the Calvin cycle is catalysed only by RuBP carboxylase. The ATP produced during
photophosphorylation is used to convert ribulose-5-phosphate to RuBP. After CO2 fixation
ATP along with reduced nucleotides from the light process change 3-phosphoglyceric acid (3PGA) to 3-phosphoglyceraldehyde (3-Pgald).
Photoperiodic effects
Eze (1987) observed the effect of five levels of daylight on amaranth and stated that the
total plant fresh weight was greatest in full light (as were both the fresh and dry weight of the
roots). Leaf area was greatest at 50% light, diminishing with increasing shade. The percentage
flowering and number of branches were greatest and senescence was most rapid in full light.
Stem weight ratio varied only slightly between treatments, they concluded that a decrease in
irradiance is accompanied by a decrease in the root weight ratio, whereas the leaf weight ratio
increases. The contents of total carbohydrate, ascorbic acid and chlorophyll a and b per unit
dry weight of leaf tissue and the chlorophyll stability index were higher at higher light
intensities. Protein accumulation was best at 70% light.
Fuller (1949) stated that A. cruentus originating from Nigeria is an obligatory long-day
plant which flowers and yield only when the day is long. While Allard and Garner (1949)
described A. hybridus L. and Amaranthus Sp. Dreer Sunrise as day neutral plants (DNP).
These workers further stated that all other Amaranthus species examined in later studies
behave as obligatory or facultative (short day) SD plants. They also observed that A. caudatus
L. in general is facultative but the variety albiflorus is obligatory. They also stated that A.
retroflexus L. and A. graecizans L. are facultative while A. tricolor L. is obligatory.
Fuller (1949) working with seed material from Bolivia, found out that C. quinoa is an
indeterminate of day neutral species. The day length sensitivity of C. quinoa was also
reported by other authors (Cardenas 1949; Leon 1964; Simmonds 1976). Fuller however
failed to find any studies concerning the photoperiodic requirements of canihua
(Chenopodium pallidicaule, Aellen).
The degree of the sensitivity of C. quinoa to day length can be found in the data of Risi
and Galwey (1991). They studied two varieties of C. quinoa and they showed that Baer
flowered earlier than Blanca de Junin. Baer has the shorter vegetative period when both
varieties are grown in their native areas, and moreover it is possible that Blanca, which
originates from low latitudes, is inhibited from flowering by long days.
The Chilean cultivars are known to perform well in European daylength where the
vegetative period usually reaches 150 days. On the other hand with cultivars from Bolivia one
observed robust vegetative growth and longer vegetative period. Ritter (1985), Risi and
Galwey (1989) explained this phenomenon as nearness of Bolivia to the equator which means
maximum variation in the daylength is several times less than in Europe. In general the crop is
considered as photoperiodically neutral. Substantiation of their claim is manifested in the
origin of the seeds, that is global in setting.
Carmen (1984) investigated acclimatisation of quinoa and canihua (C. pallidicaule, Aellen)
to Finland. The Finish experiment showed that about fifty of the quinoa ecotypes and thirtyfive canihua ecotypes produced mature seeds in Jokioinen, one of the experimental sites. The
total number of ecotypes of quinoa tested was seventy-six while that of canihua was thirtyfive. The Finish experience provides some evidence of the day length neutrality of C. quinoa
as a result of its location. The disparity in the day length within the cause of one year is
enormous compared with locations near the equator.
1.7 PHOTOASSIMILATE DISTRIBUTION
Plants allocate the carbon (C) they fix from the atmosphere to meet the demands associated
with their life: they need energy to grow and maintain their tissues and organs, they need to
reproduce or extend their life in some fashion, and they need reserves for unfavourable
periods.
Fluxes of carbon which are involved in the distribution within (partitioning) and between
(allocation) plant organs change predictably throughout the life of a plant (Dickson and
Isebrands 1993). Chapin et al. (1990) identified four time intervals over which C supply
alternates between surplus and deficits: day to night, good to poor environmental conditions,
summer to winter, and vegetative to reproductive states.
A plant’s ability to accumulate assimilated carbon is a function of its photosynthetic
capacity and pattern of carbon distribution among its parts, both of which appear to be
genetically determined (Gifford et al. 1984).
Allocation of recently fixed carbon involves a number of biochemical pathways and
compartmentation steps. In a mature leaf, most of these processes support the export of
assimilated carbon and its distribution among sinks (Geiger and Bestman 1990).
Balanced allocation of recently fixed carbon between export and reserves supplies carbon
compounds for maintaining both immediate and delayed phloem translocation (Fondy et al.
1989; Servaites et al. 1989a, b), thereby providing a vehicle of communication among regions
of the plants.
In some cases allocation also provides compounds, such as growth regulators or
metabolites, that communicate information related to the presence of the stress. In waterstressed plants, cytokinin or abscisic acid (ABA) may serve this purpose. Allocation can also
serve the purpose of providing the carbon needed for a stress response. For instance, when the
related water content of an exporting leaf falls, carbon may be allocated for synthesis of
osmotic agents in the leaf (Fox and Geiger 1986).
Allocation supports long-term reserves. which in turn supply carbon that can allow a plant
to respond to stress during a given developmental stage, at the begining of the next season’s
growth, or on germination of the next generation of plants. Daily and long-term carbon
reserves enable plants to acclimate to stress by maintaining overall fitness, maintaining
phloem translocation by way of communication and integration, and, especially, by serving as
a buffer in the event of a stress that slows or stops photosynthesis. Allocation also involves
buffer reserves. Carbon stores, located in source organs, along the translocation path, and in
various sinks, serve as buffers by providing a temporary supply of carbon that can be
mobilized whenever the supply of photoassimilated carbon becomes limited. This is to the
extent that these reserves are available for mobilization. They can negate the effects of rapid
decreases in carbon supply. For instance, when export from a leaf is drastically slowed down
by cooling a region of stem or petiole, import is maintained by mobilization of buffer reserves
(Swanson and Geiger 1967; Minchin and Thorpe 1987).
Allocation also draws from reserve carbon. Reserve carbon is needed daily, even, in the
absence of stress, for growth and metabolism. A variety of adaptations enable plants to
maintain a steady carbon supply for distribution during the daily dark period as well as to
supplement the transition hours from day to night and night to day. Allocation of newly fixed
carbon to daily reserves within exporting leaves maintains this supply. Some plants, including
barley (Gordon et al. 1982), spinach (Robinson 1984) and sugar beet (Fondy et al. 1989;
Servaites et al. 1989a) store sucrose throughout much of the day.
In nature this capacity also depends on the plant’s ability to maintain dry matter
accumulation in the face of an ever-present variety of stresses. Most plants fall far short of
their full genetic potential for productivity because of environmental stress. For a variety of
crops under field conditions, even agricultural yields are only 12 to 30% of record yields
(Boyer 1982). The ever-present stress phenomena, which in nature are frequently made-up of
different stresses lead to a search for an understanding of the ways in which allocation
integrates stress responses in different plants. Such an understanding leads to recognition, and
might preserve the genetic diversity needed for acclimation to stress in native plants.
There are two types of acclimation to the variety of stresses in nature. The short term
direct responses involve the stress-induced change in the system input or output to cause a
signal which in turn causes the system to initiate an acclimation response. For instance,
atmospheric humidity and transpiration rates are inputs for the system enabling the plant to
achieve and maintain a balanced water status and avoid desiccation (Schulze 1986). However,
direct responses are unlikely to enable the plant withstand a persistent stress. Acclimation of
plants to the events initiated by stress via responses mediated through altered gene expression
and biochemistry are those that have a meaning in counteracting a persistent stress (Queiroz
1983; Geiger 1986). The changed system output serves as a signal that sets in motion a
mechanism mediated by changes in the system itself. Changes in gene expression through
gene activation, transcription, and translation can lead to new plant responses (Sachs and Ho
1986). New structural or physiological characteristics create an altered system that restores
the original output, even though the stress-induced changes in the output are not reversed. The
successful response creates a plant with changed metabolism, biochemistry, or both, that often
can function well even though the stress persists. Under water stress, for example, initiation of
more extensive root growth can increase water uptake so that turgor is restored despite high
transpiration in the dry air (Meyer and Boyer 1981). In view of this though partitioning plays
a major role within the cells of the organs by determining what portion of the newly
assimilated carbon should be stored as starch or as sucrose in the vacuoles, distribution
between organs by way of allocation has far-reaching aims in enabling the plant to acclimate.
There are anatomical differences which show that the leaf anatomy of the C4 fixation
pathway is called the Kranz anatomy. The structure of the leaf in this anatomy reveals sheath
cells which have chloroplasts with less developed grana than in mesophyll cell chloroplasts.
These chloroplasts are also capable of storing starch unlike those in the mesophyll layer,
because the Calvin cycle is operative in them. The C3 species are lacking in specialized
sheath cells.
Furthermore differences in adaptation occur for species with different CO2 fixation
mechanisms: C3 species are adapted to cool and moist to hot and moist conditions while C4
species are adapted to hot, dry, or moist conditions.
Large differences in water use efficiency (WUE) occur when species are categorized by
CO2 fixation pathway. It is now accepted that the WUE of C4 species is generally higher than
that of C3 species (Downes 1969; Bjorkman 1971; Brown and Simmons 1979). Differences
between C3 and C4 species increase as the temperature rises from 20 to 35oC (Bjorkman
1971).
Therefore response to stress by way of distribution or normal distribution patterns of
photoassimilates have to be investigated constantly. Hence the justification of the research at
hand.
1.8 AGRONOMIC PRACTICES
1.8.1 Amaranthus cruentus aspect of study
Field preparation and sowing
Under Polish conditions most weeds germinate in early spring so it is possible to speed-up
their emergence and then destroy them by frequent harrowing. It is however noteworthy that
heavy equipment that destroy the soil structure or cause extreme drying of the top soil layer
should be avoided. Moisture is one of the most important critical factors during germination
dictating either delayance or uneven emergence. The field must be well levelled and two to
three harrowings are sufficient for sowing of amaranth seed.
Amaranth is generally sown in the first or second week of June, after the first shower.
Johnson (1990) stated that in the US there is often no penalty for late planting (as there is with
corn). In North Dakota, high yields are produced from mid-June plantings. In most temperate
countries sowing is recommended after the last frost in spring. Traditionally the seeds are
broadcasted but better crop stand is achieved if seeding is done in rows. The depth of sowing
should be less than 2 cm, as a result of very small grain size.
A row spacing of 50 cm or 20 cm is usually recommended. The higher row spacing is
frequently used where a lot of weeding is anticipated and where harvesting is done manually.
Where harvesting is mechanically done the lower row spacing is usually recommended. In the
case of the higher row spacing, allowing 20 cm between plants and using the recommended
seed rating of 1.5-2.0 kg/ha will give a good grain yield. The lower row spacing usually
requires less than 20 cm between plants with the crops more even in growth and less
branching, which favours mechanical harvesting. The seed rating of amaranth is based on the
thousand seed weight (TSW) which is about 0.7 g as compared to that of mustard which is
about 5 g (Johnson et al. 1990). The recommended plant rate per square metre is 18-30 (Josi
and Rana 1991).
Fertilizer requirement
Field observations indicate that amaranth grows well on soil containing widely varying
level of soil nutrients. This is also substantiated in Amaranth Information (1988) by stating
that amaranth, while not dictating any prefixed soil requirement for normal growth requires a
good soil well supplied with mineral nutrients. However species like A. tricolor have been
proved to be non-susceptible to saline soils (Magomiedow 1989; Buren, Vavilov 1992) and
also tolerant to high levels of aluminium (Foy and Campbell 1981; Mahus 1988). Anyway,
the level of tolerance has a limit as verified by a modified mass selection program used by
Campbell and Foy (1987) while screening four grain amaranth populations (R101 and R103
A. hypochondriacus, R123 A. cruentus, and R125 A. hybridus) for tolerance to aluminium in
pH 4.8. All four were found intolerant to high levels of aluminium. The same authors also
published results which showed that further breeding is necessary before adequate levels of
aluminium tolerance can be reached. The same workers also stated that tolerance to high
aluminium levels may be inversely or directly related to desirable agronomic traits as well as
inherited independently.
Initial studies carried out in Pennsylvania (Rodale Research Centre) showed that young
grain amaranth grew taller with fertilizer application, but the grain yield did not justify the
fertilizer application. Vegetable amaranth on the other hand, requires high soil fertility
(especially for potasium and nitrogen).
Bressani et al. (1987) stated that A. cruentus ecotypes from U.S.A. and Guatemala, A.
hypochondriacus from U.S.A. and A. caudatus from Peru were treated with 12-24-12 NPK
fertilizer at three levels 0, 30, and 60 or 90 kg. Fertilizer had no significant effect on yield, but
increased the seed protein content in the two lowest yielding ecotypes. The effect on seed fat
content was inconsistent.
Breeders from Mexico and also Weber (1990) recommended the following fertilizer level
N90-100, P 60-70, K 60-70. They recommended that fertilizer application should be split into
two stages: an initial application before sowing and at the stage of maximum intensive
growth. Other workers reported that vegetable and forage varieties are prone to benefit a lot
from nitrogen fertilizers. They however warned that excessive nitrogen can lead to the
accumulation of toxic concentrations in the plant for both man and animals (Senft 1979;
Magomiedow 1987). Oke (1979) and Mustafa (1984) recommended the use of organic
fertilizers.
Water requirement
In order to germinate and establish roots, amaranth seeds require well-moistened
soil, but once seedlings are established, grain amaranth does cope with limited water. It has
been shown to grow well under dry warm conditions. On the other hand vegetable amaranth
requires moisture throughout the growing season. Grain amaranth has been grown in dry areas
receiving as little as 200 mm of annual precipitation, while vegetable amaranth is usually
grown in areas receiving 3000 mm of annual rainfall. Indeed, in West Africa vegetable
amaranth production continues even during the torrential rainy season (Amaranth Information
1988).
Pests and diseases
According to Weber et al. (1990) the most pervasive damaging insect to date
occuring on amaranth seems to be Lygus, sometimes called tarnished plant bug (TPB) and its
economic threshold for damage was found. Wilson (1989) has summarized some insect
feeding studies on amaranth, including tests on the tarnished plant bug Lygus lineolaris
Palisot de Beauvois the fall army worm (Spodoptera frugiperda J. E. Smith), the cabbage
looper (Tri choplusia Ni Hubner), the corn earworm (Heliothis zea Boddie), and the cowpea
aphid (Aphis craccavora Koch.). It should result in breeding for insect resistance and
implementation of integrated pest management. Pesticides have not been certified for use on
amaranth. Yet ironically, given consumer concern over pesticide contamination of foodstuffs,
lack of pesticide certification may encourage introduction of the crop.
The cosmopolitan Lygus lineolarus bug (cabbage looper) has been recorded on
32 host crops. Lygus bug damages amaranth by feeding on the meristematic tissue, developing
floral buds, immature blossoms and developing embryo. The feeding causes localised wilting,
tissue necrosis, abscission of fruits, morphological deformation of fruits and seeds and also
altered vegetative growth. The damage has been caused by piercing the developing plant
organ and sucking out the juices. Other economically important pests are leaf miners, spider
mites and stem weevil which is a major pest of amaranth whose grubs damage foliage and
roots hence causing the plant to wilt. Stem borers (Lixus truncatucus) are also a serious
problem for the early developing crop in Asia and Africa causing lodging in plants. During
rainy seasons leaf rotters also cause considerable damage. Other pests of the crop are
Hypolixus nubilous (Egypt), Rhachi creagra (Costarica), Chrotogonus spp (Pakistan),
Hyphurus spp (India), Geocoris spp (California), Thysanoptera spp(Hawaii), Haplopthrips
longisetosus (India), Diabnotica barberi and Spodoptera exigna. Meloidogyne incognita,
(chitwood) root knot nematodes are serious pests of celosia that also slightly affect
Amaranthus species.
In South Mexico amaranth has also been used as a guard crop. Weedy amaranth
species are planted alongside corn fields because the pests that usually attack corn prefer
amaranth to corn leaving the corn alone (RRC 1983).
Pandy et al. (1985) while studying the leaf surface mycoflora of Amaranthus
paniculatus found minor occurrence of Fusarium oxysporum and Nectria cinnabarina where
as other species among them Alternaria alternata, A. amaranthi, Phoma glomerata, P.
hiburnica, Phyllostica spp (leaf spot), Asperigillus luchunsis and Rhizoctonia species were
commonly isolated. Furthermore soil fungus, damping off, leaf blight, white rust
mycoplasma and virus have been identified as the serious diseases of amaranth in India.
Sealy et al. (1988) screened a total of 126 accessions of species and cultivars of
Amaranthus for resistance against Pythium myriotylum. They recommended that accessions
exhibiting weighted percentage mortality of less than 20% be selected for use in breeding
programs against damping off disease. Bialoskorski et al. (1982) also observed Pythium
aphamidermatum damaging amaranth crop in Brazil. McLean and Roy (1988) reported
Colletotrichum domatium damaging Amaranthus hybridus plant in Mississippi, USA. In India
a casual organism Xanthomonas amaranthicola a bacterial leaf spot disease of amaranth has
been reported (Reddy et al. 1980).
Sharma et al. (1981) and Naseema et al. (1983) reported Aspergillus flavuus, A.
niger and Rhizopus stolonifer as the major storage fungi of amaranth crop in India. According
to Sharma and Chowfla (1987) a mosaic disease caused by a strain of cucumber mosaic virus
occured in Amaranthus caudatus. Sammons and Barnett (1987) reported that tobacco ring
spot virus damaged Amaranthus hybridus in California, USA.
Harvest
In the case of grain amaranth it is recommended that combine harvesting be
differed until there is a killing frost for temperate regions (Putnam 1991). This is to prevent
eventual shattering of harvested grain. In the tropical regions it is advisable to harvest in the
morning when the plants have optimum moisture as a result of elevated night relative
humidity. This is also a measure recommended to prevent shattering of seeds during harvest.
Mechanical harvesting is enhanced by the relative heavier weight of the grain to
the husk (Amaranth Information, 1989). Varadinov et al. (1989) stated that grain amaranth
inflorescence is about 50% of the whole plant. In the case of forage amaranth about 20% is
leaves, 30% is stem, while 45% is inflorescence.
Yield
Czernow and Zemlonoj (1991) stated that it is possible to obtain 100 tons per
hectare of leafy vegetable with a protein content of 5 tons which is even higher than that of
soya.
Maximum grain yield of 1.8 tons per hectare has been reported from
experimental fields of Pensylvania while in California twice as much has been reported. From
the Himalayas where C. hypochondriacus is the main grain amaranth a 3.0 ton per hectare has
been reported (Amaranth Information 1989).
Bressani et al. (1986) reported that out of 14 selections of four Amaranthus
species studied, six yielded over 0.3 kg m-2 and three below 0.1 Kg m-2. Grain size varied
from 1.55 to 2.14 mm and seed weight from 0.46 to 1.18 mg per seed. In the variation of yield
between selections, A. cruentus contributed the least. Plant height at flowering and yield were
not found to be related while some relationship was found between plant height at harvest and
yield. The best yielding cultivar was A. hypochondriacus (A-718) with 4091 kg/ha.
Crop rotation
It has been reported that amaranth does not leave any harmful allelopathic
effects for the next crop (Risi and Galwey 1984). Indeed where a large quantity of cereals is
involved amaranth can replace rye and wheat. In USA the most popular crop rotation is
wheat-amaranth-wheat. It is therefore effectively a break crop. A break crop should be able to
satisfy the important reason of avoiding diseases and pests of a particular crop, while the
change should not be at the expense of the soil structure and its chemical properties.
Amaranth has not been found lacking in these properties.
Amaranth as a weed
Until now there are no chemical means of weed control especially post-emergent
ones on amaranth plantations. This may be partly due to the fact that most preparations are
based on controlling amaranth as a weed. Species like A. viridus, A. spinosis, and A. hybridus
are persistent weeds of cultivated crops (Amaranth Information 1989). Indeed A. retroflexus is
one of the most noxious and popular weeds of cultivated crops. Some breeding programs have
been directed towards extracting and cloning amaranth genes that are resistant to herbicides
like atrazines so that they could be transformed to common crops such as wheat, rice, corn
etc. Weeding on amaranth plantations is usually manual and as a result of this cultivation
suffers a setback.
1.9.2 Chenopodium quinoa aspect of study
Field preparation and sowing
In the development of quinoa as an arable break crop, sowing date, sowing rate
and row spacing are identified as agronomic variables having a high priority for investigation.
The variety Baer, from high latitudes at sea-level in Chile, and the variety Blanca de Junin,
from the inter-Andean valleys of Peru, were sown on the 25th March, 14th April and 7th May
1982 at spacings between rows of 0.8 and 0.4 m and sowing rates within rows of 0.2, 0.4 and
0.6 g /m, at Cambridge, England. These varieties are chosen for their strong contrasting
origins and plant types. In another experiment sown on 15 March 1984, Blanca de Junin was
replaced by another valley type, Amarilla de Marangani, somewhat better adapted for
cultivation in England. Between-row spacings of 0.4 and 0.2 m, and sowing rates of 15, 20
and 30 kg seed / ha were used. Weed competition was more intense after later sowings,
causing the plots sown in May to be abandoned. At the higher sowing rates, plants were
shorter, a higher proportion were stunted, branching was reduced and maturity was earlier.
These effects were more marked in the valley varieties, particularly Blanca de Junin.
Increases in within-row density caused greater increases in competition effects than
corresponding reductions in row width, except for the effect on the proportion of branched
plants. The highest grain yield, 6.96 t / ha, was obtained with Baer sown in March in rows 0.2
m apart at 20 kg seed / ha. However, Amarilla de Marangani produced a higher yield at 30 kg
seed / ha than at 20 kg seed / ha, which is surprising since valley varieties are normally sown
with low target population densities or in intercrop, and Amarilla de Marangani was, in other
respects, less tolerant to competition than Baer.
Seed rates vary between United States recommendations and those of South
America. Current United States recommendations are 8 million / ha for row cropping and 20
million / ha for broadcast cultural practices. Quinoa should be sown in a row distance of 2426 cm in the middle of May (Danish conditions). The plant density should be 130-150 plants /
m2. The recommended sowing depth is 1-2cm. In general the sowing period is between the
beginning of April to May 31st (Haaber 1987).
Fertilizer requirement
Carmen (1984) postulated that the main agronomic advantages of quinoa are its
ability to grow at high elevations under semi-arid conditions and marginal soils. Haaber
(1987) stated that quinoa prefers sandy soils, and can be grown on clay soils but a reduction in
green yield and subsequently dry matter may be expected as a consequence. He continued
that in general the crop has adaptability for establishment and that compact, acidic and
indigent nutritive conditions are unfavourable for proper crop propagation. Haaber (1987)
also stated that a basal dressing of phosphorous and potassium equivalent to 65 kg P2O5 / ha
and 65 kg K2O / ha respectively is recommended with 60 kg N / ha as a basic nitrogen
fertilizer. He also recommended the use of 120-180 kg N / ha four weeks after emergence.
Ritter (1985) has stated that quinoa is a plant with a high demand for nitrogen compared to
other plants. He cited the German experience where a fertilizer application of 250 kg K2O /
ha and 150 kg P2O5 / ha resulted in 170 dt / ha of DM and 700 dt / ha fresh weight.
Water requirement
Irrigation may have a significant effect on the yield of quinoa. Tapia (1984)
indicated an average of 550 mm of available moisture as optimum. In the loamy soils typical
of the valley quinoa types, 700 mm may be required while types which grow in the saltflats of
Southern Bolivia require only 350 mm. In Colorado, Flynn (1990) found maximum yields of
1439 kg / ha were obtained on sandy-loam soils with 208 mm of water (rainfall and irrigation)
with available water levels of 128, 208, 307 and 375 mm being tested. Haaber (1987) stated
that warm weather, sunshine and suitable moisture in soil produce the optimum dry matter
yield. Heavy drought and cold severly affect the yield.
Pests and diseases
Insects are a major concern in South America and have received increasing
attention in the United States. In South America, Romero (1980) has pointed out two
important pests of quinoa: Scrobipalpula sp. which destroys buds, inflorescence, immature
and mature grain; and "leaf miner" (Liriomyza sp.) which destroys leaves and occasionally
stacks of quinoa. In Colorado, Cranshaw et al (1990) found on quinoa some insects
commonly associated with sugar beet and lambsquaters (C. album L). Seedling damage was
caused by Malanotrichus coagulatus Ulher and Atomoscelis modestus Van Duzee and the
seed bug, Nysius raphanus Howard. Foliar pests involve two leaf miners, Pegomyia
hyoscyami Panzer and Monoxia nr. Pallida Blake. Also found were leaf feeding insects such
as leaf curling aphid Hayhursita atriplitis (L.) and various Lepidoptera, such as Spodoptera
exiqua Hubner. A foot, or root feeding aphid, Pemphgus populivenae Fitch, caused late
season damage. Seed damage was due to Lygus spp.
Haaber (1987) stated that green and black flies Myzus persicae and Aphis fabae
respectively have been identified as pest. Dawney mildew (Peronospora farinosa) has not
been implicated as a disease attacking quinoa meant for vegetable use.
Quinoa as a weed
Weed control has a major impact on quinoa yield. It is largely manual for now,
as in the subsistence agricultural systems of the Andes. This is so because a form C. album
known in Britain as fat hen and lamb’s quarters in North America is distributed world-wide as
an annual weed on arable land. The dividing line between a weed and a crop is often thin: the
seeds of C. album were used as food by the former inhabitants of Russia, Denmark, Greece
and northern Italy (Renfrew 1973). However where mechanization or chemical control is
envisaged row width should be enlarged. In Colorado, grassy weed control alone increased
yields from 640 kg / ha to 1822 kg / ha (Johnson 1990). In England, Metamazide, Propachlor,
Linuron, Propyzamide and aloxium sodium did not significantly reduce plant stands of two
quinoa cultivars (Galwey and Risi 1984). In Colorado preliminary herbicide studies of preemergent herbicides with Dual, Furloe, Sutan and Antor showed good crop safety and control
of grasses and many broad-leaf weeds (Westra 1988).
Harvest
Harvesting for forage should be done nine weeks after emergence. When the dry
matter and protein content are at maximum (Haaber 1987). Where the crop is meant for grain
purposes, the optimum time for harvest is the stage of complete maturity of grains. In the
Andes where the crop originates mechanical harvesting was unknown. However, in many
temperate or mechanical environments where the crop is gaining increasing ground,
mechanical harvesting is very much preferred. Growth attributes like reduction in plant height
and early maturity did not play any role in the cultivation of quinoa as a subsistence crop.
Presently screening and breeding research programs frequently include these attributes as they
are proving increasingly essential if quinoa is to enter into urban and international markets
(Risi and Galwey 1991). Carmen (1984) also stated the possibility of mechanical harvesting
of plants.
Yield
To obtain high yields of a good quality animal feed from quinoa, the crop should
be harvested nine weeks after emergence under northern conditions. Protein content and dry
matter yield (DMY) would then be as follows: In the case of 180 kg N ha-1 fertilizer
application, DMY is 11.4 t /ha while protein is 16.2%. If fertilizer application is 240 kg N ha1 DMY is 10.7 t/ha and protein is 18.3% (Harber 1987). Indeed the response to nitrogen
fertilization has been observed in both South America and Colorado (Gandarillas 1982).
With regards to grain yield, Weber (1978) stated that it varies according to
growing conditions - from as low as 450 kg / ha to as high as 2000. The average yield is about
800 to 1000 kg/ha on the Altiplano. A record yield of about 5000 kg/ha has been reported
under ideal conditions near Lake Titicaca, using cultivar Sajama developed in Bolivia.
Crop rotation
Weber (1978) stated that highland farmers often cultivate quinoa in rotation with
other crops because they believe it can prevent diseases among other crops. Quinoa itself is a
prey principally to mildew and leaf spot, though its most serious enemies are birds. According
to an experiment in Equador (unpublished), it is risky to grow quinoa continuosly. The risk is
the formation of two nematodes and one of them can attack potatoe (Solanum tuberosum).
Therefore a good rotation is necessary as a precaution.
On the other hand, Risi and Galwey (1984) stated that one of the varieties
investigated for use as a break crop namely Amarilla de Marangani, produced a higher yield
at 30 kg seed / ha than at 20 kg seed / ha, which is rather surprising since valley varieties are
normally sown with low target population densities or in intercrop. Although the implications
of this result have got to be carefully analysed before conclusion, it can however be intuitively
stated that there is proof of adaptability of the variety to temperate climate. Also it can be
stated that there is a basis for further research as to its adaptability as a brake crop like rape.
Indeed the results of the Cambridge experience suggested that C. quinoa is a good contender
as a break crop like rape.
2 METHODOLOGY
2.1 GROWTH CONDITIONS
2.1.1 POT EXPERIMENTS
These experiments were set up with a view of investigating differences in
gaseous exchange and harvest index (HI) due to fluctuations in the water table. Furthermore
they were also meant to reveal actual differences in growth and yield between species and
combinations. Plot experiments show water tables with diurnal, seasonal and climatic
changes. The investigator has very little or nothing to do with regards to influencing the water
table by way of water table fluctuations. The non-irrigated combinations in the two years field
experiments (1992 and 1993), in particular, were independent of the investigator. On the other
hand, the water table in the pot experiments was investigator descretional. The experiments
were conducted with pots filled with 11.46 kg of a mixture of soil and sand 2:1 V/V. The soil
moisture in the pot experiments had two levels. At high soil moisture level, 7.6% of the
weight of the soil was moisture, 80% of the total pore space was filled with the moisture
while the lower case had 5.6% of the weight of the soil, as moisture and 40% of the total pore
space was filled with moisture. The moisture levels of 80% and 40% corresponds with soil
moisture levels at field capacity and temporary wilting point respectively.
Fertilizer application was carried out on these pot experiments. Specific
description concerning its application is explained under each experiment.
1992 INFRA RED GAS ANALYZER EXPT. (INFRALIT IV).
Two species Amaranthus cruentus and Chenopodium quinoa a Danish select
were grown in pots prepared as mentioned above. The plants were transplanted into test tubes
at the seedling stage. The roots were completely dipped in water. The plants were left in this
state overnight to allow for a new equilibrium in its general metabolism in the new
environment be fixed before measurements were started.
1992 EXPERIMENT
The seeds for this experiment were sown on the 14-02-92 and a lapse of 31 days
was allowed for the plants to establish before they were transplanted into pots. There were 28
pots in all. Fourteen pots were assigned to each of the two species to cover two moisture
levels. Each level had 7 pots. One level had soil moisture at field capacity (80%), while the
other was at temporary wilting point (40%).
Field capacity is the water level of a soil system when all gravitational water has
drained (Brady 1984). The percentage of the water in the soil was 7.6 that of the dry weight of
the soil. The dry weight of the soil was 6 kg. The weight of the water in the pores was
therefore 0.46 kg. The total weight was the sum of the weights of the dry soil, the water in the
soil pores, the sand and stones plus the empty pot. If as earlier-mentioned the dry soil weighed
6 kg, the water in the pores weighed 0.46 kg the sand, stones and the empty pot together
weighed 5 kg. The total weight was therefore 11.46 kg. The pF of soil was 2.4 which
approximated 250 hPa.
The second level of soil moisture was intended to subject the plants to temporary
wilting. This level of soil moisture was kept constant throughout the experiment as in the field
capacity combination. At temporary wilting point the water level in the soil pores was 5.6% of
the weight of the soil in the pot. The water weighed 0.3 kg of water when 100% of soil
weighed 6 kg. The total weight of the pot 11.3 kg was the sum of the dry weight of the soil,
the water in the soil pores, the sand, stones and empty pot. The pF was 3.0 and this was
appoximately 1000 hPa.
Fertilizer application, (table 13), was carried out on both species. In the case of
A. cruentus, there were three applications while there were two with respect to C. quinoa. The
first application before sowing was similar in both species, while the second differ in
composition with respect to species. There was a third fertilizer application for A. cruentus.
Two types of fertilizers were applied to each pot. There were those containing
macroelements and those containing microelements. However in some applications there were
no compounds containing microelements.
Combinations were differentiated out during the three leaf stage. Before then the
plants in the pots were receiving the same treatment by way of addition of water.
1994 EXPERIMENT
The date of sowing was 20-05-94 and that of emergence was 22-05-94. The
seedlings were transplanted on the 03-06-94. Combinations were separated out on the 05-0694. The one day experiment was carried out during the flowering stage of growth on the 20th
July 1994.
This pot experiment had similar fertilizer application, soil structure and
composition as already mentioned for the 1992 experiment. The only difference in fertilizer
application was that A. cruentus had no third application. The second fertilizer application
took place on 08-07-94. Also the combinations which were based on soil moisture level were
different. The experiment had two combinations for each species. Each combination had three
pots. One of the combinations had constant moisture. The said moisture level was 7.6% the
weight of the soil in the pot (80% of the pores were filled with moisture). The weight of the
pot was maintained at 11.46 kg throughout the experiment. The other combination had an
initial soil moisture level and weight of pot as the earlier-mentioned combination but no
further addition of water was effected throughout the experiment.
2.1.2 PLOT EXPERIMENTS
The two years plot experiment involved in the growth analysis were set up
against the same background, by way of species and combinations. There were two species,
namely A. cruentus and C. quinoa a Danish select. There were two levels of soil moisture for
each of the species. There was the combination that was exclusively rain-fed while the other
level involved additional periodic irrigation, of about 4 mm per day excluding rainy days,
with a view of preventing the harzards of temporary wilting. The species, quinoa, was
Peruvian by origin from which a breeding line KLV 0188 was developed. The line is noted
for, among others, beneficial characteristics for agronomic and mechanical propagation. The
short vegetative period, the large contribution of the assimilatory surface area, lots of seeds,
and the high protein content reaching 21% were among the noted characteristics. Each of the
two species, in turn, had two combinations. One of the combinations was exclusively rain-fed
while the other was irrigated from time to time, with a view of preventing the hazards of
temporary wilting.
The experimental plots for the two years plot experiments were located on the
site assigned to the Department of Plant Physiology of the Warsaw Agricultural University in
Rakowiecka street. The crops were planted on a soil that comes under IIIB-IVA Bonification
classes. Soil analysis done in the Department of Physiochemical Analysis of SGGW, in 1992
before sowing showed that N, P, Mg, Ca, K, Fe, Zn, Mn and Cu, had 1000, 860, 1380, 1825,
2650, 1069, 107, 116 and 12.9. Before the initial experiment in 1992 white mustard was
growing on the plot as a break crop. The break crop was ploughed-in in winter. In spring the
plot was aerated by harrowing.
Fertilizer was applied to all combinations. In the case of A. cruentus 100 kg/ha of
nitrogen (urea) was applied. Initially 1/2 was applied before sowing, while the other 1/2 was
applied during the stage of stem elongation. An application of 70 kg/ha of P in the form of
Tri-superphosphate and 70 kg/ha of K (potassium salt) 60% was made before sowing.
In the case of quinoa 150 kg/ha nitrogen (urea) was applied. Two thirds was
applied before sowing, while 1/3 was applied during the stem elongation stage. An application
of 150 kg/ha of phosphorus P (Tri-superphosphate) and 150 kg/ha of potassium K (potassium
salt) was made before sowing.
Each combination of the two species had four replications. The replications were
carefully arranged so as to remove soil property differencies. The seed beds were 4 x 1.5m in
dimension. Weeding on the seedbeds was manually done while harrowing between rows
effectively suppressed weeds. In late June the crops were sprayed with Decis, against aphids.
Sowing was done in rows on the 18th of May in the case of A. cruentus in both
cropping seasons. These dates correspond to the time when the spring chilling effect had
passed away under Polish climatic conditions. The distance between rows was 30cm. The
rows were laid across the breath of the shallow seed beds. Depth of sowing was 1cm. The
seeds emerged a few days after sowing. In the case of the 1993 experiment a day or two was
enough for the emergence, while four days were observed in 1992 for C. quinoa seeds.
Moisture difference between the two years was considerable as there was more precipitation
in 1993.
In the experiment of 1992 first thinning was done on the 02-06 -92, with respect
to C. quinoa, (17 DAE). The second thinning on this same crop was done on the 09-07-92 (34
DAE). The first thinning on A. cruentus was done on the 14-06-92 (21 DAE), while the date
for the second thinning coincided with that of C. quinoa on the 09-07-92, (47 DAE).
With regards to the experiment in 1993, the first thinning on C. quinoa was done
on the 04-06-93, that is (14 DAE). The thinning on A. cruentus was done on the12-06-93, that
is 22 DAE on the 21- 05-93. The second thinning in both crops was done on the 19-06-93, (29
DAE).
In 1992, there were eight aimed destructive harvests for A. cruentus done 28, 38,
49, 59, 70 79, 91, 99 DAE. With regards to C. quinoa there were seven such harvests carried
out 38, 52, 61, 69, 81, 89, 102 days after emergence.
In 1993, there were ten aimed destructive harvests for A. cruentus carried out
22, 32, 42, 52, 62, 72, 82, 92, 102, 112 DAE while there were nine such harvests in the case
of C. quinoa carried out 22, 32, 42, 52, 62, 72, 82, 92, 102 DAE.
2.1.3 METEOROLOGICAL PARAMETERS.
The total rainfall and daily mean temperature in 1992 are displayed as figure 38
while those of 1993 are displayed as figure 39 and the calculated Sielianinow’s hydrothermal
index (1930) for the two consecutive years is displayed as figures 40.
K=
P
01
. t
Where P - Total precipitation (in mm)
Where K - is the index of dryness
t - is the mean monthly air temperature in 0 C
When K is below 1, the climatic condition is described as dry. This condition
will lead to plants losing more water through transpiration than it is receiving from
precipitation. When K is below 0.5 the condition is described as intensive dryness.
2.2 GAS EXCHANGE MEASUREMENTS
2.2.1 POT EXPERIMENTS
1992 INFRA RED GAS ANALYZER EXPT. (INFRALYT IV).
PHOTOSYNTHESIS AND RESPIRATION
All the measurements of gaseous exchange were done using the Infra Red Gas
Analyzer Infralyt IV, Jankalor, Germany. Three measurements involving three plants were
carried out. The system included a cooler to facilitate chilling temperatures. The
measurements were taken between 9 am and 1 pm . Avoidance of carrying out the
measurements after 1 pm was deliberate as in winter, when the experiment was carried out,
photosynthesis was observed to be tremendously reduced after 1 pm notwithstanding added
artificial irradiance or other optimum conditions.
Seven temperature levels 10, 15, 20, 25, 30, 35 and 40 degrees centigrade were
arbitrarily chosen for the taking of measurements. The temperature levels were meant to
simulate Polish conditions. The assimilatory surface area was measured with the use of the Li1000 planimeter equipment manufactured by Lambda instrument Corporation of Nebraska,
USA. The time taken by the assimilatory surface of enclosed seedlings in the air-tight gas
cylinder to reduce the CO2 concentration from 350 to 250 ppm was noted by a stop watch.
The time, in seconds, was then slotted into equations to calculate the rate of photosynthesis.
Dry matter of the samples was secured by oven drying at 1050 C for 1/2 h and then for 24 h at
0
75 C.
Relative photosynthesis and relative respiration were deduced by dividing a
given value by the highest one within the data at a particular temperature and the quotient
2
1
expressed as a percentage. True photosynthesis expressed in mg of CO dm- h- (1 mg of
2
2
1
CO2 dm- h- = 0.6313  mol-1 CO2 m-2 s-1) was the sum of photosynthesis and respiration at a
given temperature. The ratio of photosynthesis to respiration (P/R) was the ensuing quotient
when photosynthesis was divided by respiration.
In a bid to provide satisfactory irradiance two mercury lamps were used. One on
each side of the chamber. Each lamp had a wattage of 250 and provided an average irradiance
of 500 mol m-2 s-2 inside the chamber.
The time taken for the concentration of CO2 in the Infra Red Gas Analyzer
system, containing a sample of plant, to rise from 250-350 ppm was equally noted for the
various temperatures (10-400 C). The time was then slotted again into the same series of
deductions mentioned above, under photosynthesis, in obtaining the time in hours it takes for
a given assimilatory surface area in dm2 of plant material to respire the given mass in mg of
CO2. The glass cylinder itself was covered with a dark piece of cloth to allienate irradiance
and hence promote respiration.
1992 EXPERIMENT
Gas exchange measurements were started a few days after combinations had
been separated. The measurements were spread throughout until maturity of plants.
Below is the time schedule of some of the measurements.
04 - 03 - 92
06 - 03 - 92
15 - 04 - 92
02 - 05 - 92
12 - 05 - 92
The data were analysed with the use of Analysis of Variance (ANOVA) to test
actual differences due to species and combinations in gas exchange, its parameters and other
attributes. Furthermore regression analysis was carried out to test the strength of the
relationship between gas exchange parameters. The pot experiments were harvested on the
29-05-92.
1994 EXPERIMENT
The first weight of pot when respiration rather than photosynthesis was recorded
was the main objective of the combination. Gas exchange measurements were started at 11 30
am and were carried out every thirty minutes. The measurements were stopped at 1: 30 pm.
The data were analysed with Analysis of variance (ANOVA) to find the
significant differences between species and combinations in gas exchange and other
parameters. Among them were the internal concentration of CO2 (Ci ) and stomatal
conductance (Cs).
2.2.2 PLOT EXPERIMENTS (1992 and 1993)
There were two plot experiments one in 1992 and another in 1993. These
experiments involved periodic destructive harvests of the two species A. cruentus and C.
quinoa a Danish select. A day before or after every aimed destructive harvest gas exchange
measurements were made. The experiment lasted throughout the cropping season. Gas
exchange parameters were measured using Li-Cor 6200 infra red gas analyzer.
In 1992 gas exchange measurements were carried out on the following dates:
12 - 07 - 92
23 - 08 - 92
24 - 07 - 92
30 - 08 - 92
03 - 08 - 92
14 - 08 - 92
In the following year (1993) gas exchange measurements were carried out on the
following dates:
01 - 07 - 93
06 - 08 - 93
11 - 07 - 93
12 - 08 - 93
22 - 07 - 93
2.3 MINERAL RELATIONS
With regards to the mineral aspect samples were drawn from two destructive
harvests. One of them was at maximum leaf area index (LAI) while the other was at the end
harvest. Coincidentally there were instances when the maximum LAI occured in the end
harvest.
Macro and micronutrient analysis was carried out on the branches, leaves, seeds
and stems. The organs were first grounded. Two grams of sample in two replications was
heated in the oven to a temperature of 4500C for three days. The ash was dissolved in a 20%
5ml of HCl. The solution was later transfered to a 25ml volume flask and then the contents
were made up to the level of the meniscus with redistilled water. The contents were diluted
ten or hundred times before determination, depending on the element. Determination of Ca, P,
Mg, K, Na, Fe, Zn, Cu, and Mn was made by the Atomic Absorption Photospectrometer
(AAS) instrument. Nitrogen was determined by the kjeldahl method and 0.5g of subsample
was used for the determination. The reading from the instrument was then multiplied by the
factor 6.25 to calculate crude protein (%CP).
The means were then compared for differences due to species, combinations and
cropping season.
2.4 PHOTOASSIMILATE DISTRIBUTION EXPERIMENT (1993)
The pot experiment was set up with a view of testing eventual differences
between both studied species and combinations, in the partitioning of photoassimilates. There
were two combinations for each species just as already described under section 2.1.1. The
fertilization of the plants was also similar to that already stated under the afore-mentioned
section.
Labelling of the plants with
14
CO2 was done during the early flowering stage.
The whole pot was placed in a temperature controlled chamber connected with IRGA in a
closed system. The chamber was illuminated by placement under direct sunshine to provide
satisfactory irradiance. After the steady state was achieved (on the basis of time needed for
100 umol m-2 s-1 of CO2 absorption in the range 350-250 mol mol-1 ) the plants were
exposed to 4  Ci of 14CO2 which had been injected by a syringe into the system. Radioactive
CO2 was generated by addition of sulphuric acid to labelled sodium bicarbonate in the
following reaction:
NaH 14CO3
14
CO2
+ H2SO4
NaH 12CO3
 Na2 SO4 +
+ 2H2O
12
CO2
The remaining 14CO2 was fixed by KOH.
Immediately after exposure the first harvest was done. The second harvest was
done two weeks after labelling. The harvested plants were randomly sampled from pots.
There were three pots for both soil moisture combinations in each species making a total of 12
pots in the experiment. Three plants were drawn from each combination at each harvest. This
amounted to a total of twelve plants for each harvest.
Each harvested plant was separated as leaves which were divided into top, mid
and bottom, the inflorescence, stems, petioles, branches and fallen leaves. Dry weights of
specific organs were recorded and then the plant material was grounded into a fine powder.
Two subsamples weighing between 0.5-1.0g, were taken for oxidizing in the Packard sample
oxidizer 300. Radioactivity was measured by the Beckman liquid scintilation counter LS
8000.
The counts per minute (cpm) from the Beckman were first transformed into
disintegrations per minute (dpm) by interpolating from a standard curve. The standard curve
had efficiencies on the Y-axis while the H# or sample channel ratios (SCR) occupied the Xaxis. The H# and the SCR were automatically supplied by the program in the LSC developed
for counting the radioactivity.
The curve was drawn by calculating the efficiencies of quenched and
unquenched factory radioactive samples in factory-sealed vials. The calculation required
observed values (cpm) and expected values (dpm). The expected values were supplied by the
manufacturers.
The radioactivity of each organ was derived by establishing a relationship
between the radioactivity of the subsample and the weights of the subsample and that of the
organ itself. The specific radioactivity was derived by dividing the radioactivity of organ or
subsample by the weight of organ or subsample. The total radioactivity was the sum of the
radioactivities of the contributing organs.
2.5 GROWTH ANALYSIS (1992 and 1993)
The classical methods of growth analysis were used to follow the growth and dry
matter (DM) accumulation of the two species in their two combinations during the cropping
seasons involved (1992 and 1993).
INDICES OF GROWTH
Periodic aimed destructive harvests were carried out. Each time five plants were
harvested from each replication. Forty plants were harvested from each combination. An
equal number of forty plants were also havested from each species at each destructive harvest.
This made a total of eighty plants at each aimed destructive harvest. The aerial parts of the
plant were involved in the analysis. Therefore the plants were cut at the base of the stem. The
roots were excluded. Ideally, all living tissue of the crops growing in the sampled area should
be measured, but the difficulty of sampling roots often excludes their use in some crop growth
rate (CGR) studies.
The plants were later separated into Leaves, stems, branches, petioles,
inflorescence and seeds. For one plant of each combination of every species total assimilatory
surface area was measured separately. The measurements were made with the use of
photoplanimeter 3000A, (Lambda Instruments Corporation, Nebraska, USA). The surface
area of the stem was calculated as 1/3 the product of the circumference and the length. The
total surface area of each organ of the five plants in each combination was calculated by
establishing a relationship with the earlier-measured single plant surface area. The dry matter
(DM) of each organ was determined separately and then that of the whole plant was
calculated as the cumulative DM of the organs.
Other indices like Crop Growth Rate (CGR) and Leaf Area Index (LAI) were
calculated using the basic attributes such as assimilatory surface area, ground surface area
covered by the assimilatory surface area and sometimes a combination of the said attributes
and other indices calculated by the IBM program earlier-mentioned.
The indices used in the growth analysis were divided into two groups. One of the
groups consists of indices dealing with single plants while the other group consists of indices
dealing with canopies.
SINGLE PLANTS
1) RGR (Relative Growth Rate). This is the change in biomass (dW) per unit of
existing biomass.
log W2 - log W1 1 dW
=
W dt
t 2  t1
RGR =
2) ULR (Unit Leaf Rate). The index is otherwise called NAR (net assimilation
rate). It is the change in biomass (dW) per unit time (dt) not less than a 24-hour day, per unit
of any measurable attribute of the assimilatory surface (assimilatory surface area, chlorophyll
etc.).
ULR =
2 / W 2  W1 /
1dW
=
/ A1  A2 / x / t 2  t 1 /
A dt
This equation is employed on the
assumption
that alpha assumes values from 1.5-2.5.
3) LWR (Leaf Weight Ratio). This is the contribution of the assimilatory surface
area (WL) in the total dry matter (W).
WL
Where W is the biomass of the whole plant.
W
LWR =
1
/LWR1 + LWR2/ Where the LWR1 and LWR2 are the values of two
2
successive measurements.
LWR =
4) SLA (Specific Leaf Area). The index relates the area of the assimilatory
surface area (A) to its biomass (WL ).
SLA 
A
Where WL is the biomass of the leaves.
WL
1
/ SLA1 + SLA2/ Where SLA1 and SLA2 are the values of the index for
2
SLA =
successive harvests.
5) LAR (Leaf Area Ratio). The index relates the assimilatory surface area (A) to
the biomass of whole plant (W).
LAR = SLA + LWR =
WL
A
+
After cancellation of common terms
WL
W
LAR becomes:
LAR =
A
W
LAR =
1
/LAR1 + LAR2/ Where LAR1 and LAR2 are the values of
2
the index for successive harvests.
Relative Growth Rate (RGR, R), Unit Leaf Rate, (ULR) Leaf Area Ratio (LAR),
Leaf Weight Ratio (LWR), Specific Leaf Area (SLA), used in following the growth and
development of single plants and clones were calculated using computer program “Jantar”
developed by Tarlowski (1992).
CANOPY
1) CGR (Crop Growth Rate). The change in the canopy biomass (dWc) per unit
time not less than a 24-hour day, per unit ground surface area covered by crop (P).
CGR =
1
1
d Wc
Wc2 - Wc1
x
=
x
Where Wc1 and Wc2 are the
t 2  t1
P
P
dt
values of the attribute for successive harvests.
2) LAI (Leaf Area Index). This is the ratio of the assimilatory surface area of a
canopy to the surface area of the ground (P) covered by that canopy.
LAI =
Ac
P
LAI =
1
/LAI1 + LAI2/ Where LAI1 and LAI2 are the values of the 2 index for
2
successive harvests.
3) ULRc (Unit Leaf Rate). This is the specific productivity (Net Assimilatory
Rate) of a canopy. It is the change in biomass of a canopy (dWc) per unit time, not less than a
day, per unit of the surface area of all the assimilatory organs in the canopy (Ac) (Pietkiewicz
1985; 1985a).
ULRc =
1
d Wc
x
AC
dt
4) LAD (Leaf Area Duration). This is the index that denotes the time the crop
had assimilatory surface. Which very often seems to be more important than LAI. It is
calculated as the summation of the LAI over the period the crop has been carrying the
assimilatory surface.
Indices like Crop Growth Rate (CGR) and Leaf Area Index (LAI) were
calculated using the basic attributes such as assimilatory surface area, ground surface area
covered by the assimilatory surface area and sometimes a combination of the said attributes
and other indices calculated by the IBM program earlier-mentioned.
STATISTICAL CALCULATIONS
Statistical operations were employed on the measurable attributes such as mass
and area of plant material. There were measures of central tendency such as the arithmetic
mean. To find the significant differences ANOVA method as well as variance and standard
deviation were employed too.
3 RESULTS
3.1 GAS EXCHANGE EXPERIMENTS
3.1.1 INFRA RED GAS ANALYZER EXPERIMENT, INFRALYT 4
In (fig. 1 (I)) quinoa had the higher photosynthetic value at 10o C and the same result was also
observed at 15o C and 20oC when quinoa had its maximum photosynthesis. It was also
observed that the gradient of amaranth was all the time rising steadily.
The photosynthesis of quinoa dropped steeply after the 20o C maximum, while that of
amaranth was rising. The photosynthesis rate of amaranth reached its maximum level at 35o C
after that it started to fall with a steep gradient. The recorded fall at 40o C of amaranth initial
while it was the least for quinoa.
The respiration of quinoa (fig. 1 (II)) was higher at 10o C than that of amaranth. It rose with a
steady gradient reaching a peak at 25o C, before it started falling. The respiration of amaranth
on the other hand rose from 10o C to 20o C with a somewhat small gradient. Above 20o C that
it started to rise steeply until 30o C. After that it started to rise with a small gradient. A fall in
respiration was not recorded for amaranth. The fall in respiration of quinoa between 25o C and
40o C was with a small gradient relative to the rise observed between 10o C and 25o C.
In (fig. 2 (I)) the ratio of photosynthesis to respiration is clearly higher for
amaranth than quinoa at the initial temperature of 10o C. The ratio increased through 15o C to
20o C which was the climax. It fell steeply at 25o C and continued falling till 35o C with a
small gradient. It again fell steeply at 40o C. The ratio of quinoa rose steeply from 10o C to
25o C. It then levelled off between 25o C and 30o C, before it started falling through 35o C to
40o C with a small gradient relative to the one it rose. The ratio of photosynthesis of quinoa
had lower values than that of amaranth throughout. In (fig.2 (II)) the true photosynthesis of
quinoa was initially higher than that of amaranth. The curve rose steeply to a maximum at 20 o
C, before it started falling. It fell right through to 40o C. The true photosynthesis of amaranth
rose steadily until 35o C. Then it fell to 40o C with a steep gradient. It was observed that the
true photosynthesis of quinoa was higher than that of amaranth up to 25 o C. It was after that
temperature an inversion of that progression was observed.
The relative photosynthesis and relative respiration for both amaranth and quinoa
are shown on (fig. 3).
3.1.2 POT EXPERIMENT (1992)
The means of photosynthesis ranged 9.46-30.35 and 8.5-23.7, 4.47-6.68 and 5.38-9.05 mol
m-2 s-1 for A. cruentus in the low and high soil moisture levels and for C. quinoa a Danish
select in the low and high soil moisture combinations respectively. The original data are not
shown here. The internal concentration of CO2 varied from 49.26-245.67 and 31.4-233.07,
141.73-179.2 and 155.70-232.8 mol mol-1 in the same combinational order as in
photosynthesis. Transpiration ranged from 1.2-9.3 and 1.1-5.9, 0.77-1.23 and 1.13-3.4 mmol
H2O m-2 S-1, in the same respective order as in photosynthesis. Irradiance ranged from 420.571218.33 and 194.9-1249.3, 227.17-303.4 and 206.07-797.87 mol m-2 s-1 in the same order as
in photosynthesis. The stomatal conductance (Cs) was 0.15-0.91 and 0.12-0.89, 0.09-0.16 and
0.13-0.92 cm s-1. The water use efficiency ranged from 3.55-9.0 and 3.00-9.82, 5.00-6.00 and
5.00-8.00 mol CO2 mmol H2 O-1 in the same order assigned to photosynthesis.
The effect of soil moisture on the DM of the plant organs of this experiment are displayed as
(fig. 4) while that on the length and DM of the whole plant are displayed as (fig. 5A and 5B)
respectively. The denotation DM in figure 4 means dry matter while HSM and LSM in the
legends of (fig. 4 and 5) mean high and low soil moisture combinations respectively.
The effect of soil moisture on the DM of organs (fig. 4) showed that high soil moisture
combination of amaranth had the heavier weight almost 4.5g of leaves while the low soil
moisture combination had about less than 4g. The leaves of the high soil moisture
combination of quinoa were also heavier than those of the low soil moisture combination. The
leaves of amaranth were heavier than those of quinoa.
The stems of the high soil moisture level of amaranth (fig. 4) were heavier than those of the
low level combination. In quinoa the difference between the two combinations was greater.
The high soil moisture combination had the higher value.
The seeds of the high soil moisture of amaranth had heavier seeds than the low soil moisture
combination. In quinoa the difference was again observed to be greater and the higher case
moisture level clearly led. The amaranth seed values were higher than those of quinoa. The
higher moisture level of amaranth led in the weight of roots. The same was observed in the
case of quinoa. The difference was also observed to be wider for quinoa between the two soil
moisture levels. Between species revealed that quinoa had the higher value.
The high soil moisture level of amaranth (fig. 5 (A)) had the longer lengths of plants than the
lower moisture case. The same was observed for quinoa although the difference was almost
indiscernible. When the two species were compared quinoa had the longer lengths of plants.
At the whole plant level (fig. 5 (B)), the high moisture case of amaranth outweighed the lower
moisture one. The same was observed in quinoa. Comparison between species showed that
amaranth outweighed quinoa.
3.1.3 POT EXPERIMENT (1994)
Photosynthesis ranged from 27.1-32.4, 14.6-30.5, 11.2-29.52 and 1.21-29.3 umol m-2 s-1 for
A. cruentus for the constant and variable soil moisture combinations and for C. quinoa
constant and variable soil moisture combinations respectively. The internal CO2 concentration
ranged from 64.5-83.7, 54-78, 161.5-202.13 and 160.1-198 mol mol-1 in the same respective
order as mentioned above for photosynthesis. Transpiration ranged from 3.4-5.1, 2.51-4.61,
4.2-8.8 and 1.0-8.7 mmol H2O m-2 s-1 in the same respective order as in photosynthesis. The
stomatal conductance varied from 0.45-0.61, 0.21-0.54, 0.34-0.81 and 0.08-0.82 cm s-1 in the
same respective order as in photosynthesis. The water use efficiency (WUE) varied from 5.41
9.6, 5.6-9.9, 1.8-3.3 and -1.1 to 3.4 umol CO2 mmol H2O- in the respective order assigned to
photosynthesis.
The results of photosynthesis for the variable and constant moisture for A.
cruentus and C. quinoa in 1994 are displayed as (fig. 6).
3.1.4 FIELD (PLOT) EXPERIMENT (1992)
Photosynthesis ranged from 23.86-57.98 and 18.77-43.35, 15.42-45.34 and 13.96-36.76 umol
m-2 s-1 for A. cruentus irrigated and non-irrigated combinations, C. quinoa irrigated and nonirrigated combinations respectively. The internal concentration of CO2 ranged from 16.8180.70 and 31.58-192.77, 161.4-225.43 and 145.23-279.4 mol mol-1 in the same respective
order as in photosynthesis. The transpiration ranged from 2.6-9.1 and 2.37-9.2, 4.2-13.7 and
3.6-11.3 mmol m-2 s-1 in the respective order mentioned above for photosynthesis. Irradiance
varies from 884.3-1636 and 914.3-1466, 881.8-1469.67 and 529.47-1221 umol m-2s-1 in the
same respective order above for photosynthesis. The stomatal conductance ranged from 0.561.99, 0.27-2.35, 0.49-2.39 and 0.38-2.48 cm s-1 in the same order as in photosynthesis. The
water use efficiency (WUE) ranged from 4.2-15.4, 4.2-9.0, 2.1-7.5 and 2.2-4.9 umol CO2 per
mmol H2O, in the order earlier-mentioned in photosynthesis.
3.1.5.FIELD EXPERIMENT (1993)
Photosynthesis ranged from 33.07-37.38 and 21.48-40.03, 25.05-46.35 and 15.51-44.04 umol
m-2 s-1 for A. cruentus irrigated and non-irrigated combinations, C. quinoa irrigated and nonirrigated combinations respectively. The original data are not shown here. The internal CO2
concentration ranged 120.39-191.11, 101.21-180.6, 94.53-268.19 and 103.13-257.48 ppm in
the same combinational order assigned to photosynthesis above. Transpiration ranged from
2.3-3.4 and 1.4-4.8, 2.2-15.2 and 2.3-9.7 mmol H2O m-2 s-1 in the respective order earliermentioned. Irradiance ranged from 1007.54-1752.66 and 1123.5-1535.89, 1176.25-1643.25
and 831.73-1659.22 umol m-2 s-1 in the respective order assigned to photosynthesis. The
stomatal conductance ranged from 0.52-1.36 and 0.34-1.66, 0.49-3.75 and 0.54-2.69 cm s-1 in
the respective combinational order assigned to photosynthesis. The water use efficiency
(WUE) ranged from 9.7-16.3 and 6.1-9.5, 3.0-11.4 and 3.5-10.9 umol CO2 per mmol H2O in
the respective order assigned to photosynthesis.
3.1.6 HISTOGRAMS
The influence of soil moisture on photosynthesis of amaranth and quinoa is presented as
(fig.35). In (fig. 35 (I)), the irrigated amaranth had a mean of 35 umol m-2 s-1 in 1992. It was
35.3 umol m-2 s-1 in 1993 while the grand mean derived by taking the average of the two
means was also 35.2 umol m-2 s-1. In the irrigated quinoa (fig.35 (I)), the observation was
markedly different from that of amaranth. In 1992 the mean photosynthesis was about 27.6
umol m-2 s-1 while it was 32.6 in 1993 and the grand mean was 30.1.
In (fig. 35 (II)) the non-irrigated value of amaranth in 1992 was 28.4 umol m-2 s1
while it was 30.9 in 1993 and the grand mean was 29.2 umol m-2 s-1. Quinoa had a value of
25.2 umol m-2 s-1 in 1992 while that in 1993 was 28.5 and the grand mean was 26.9 umol m-2
s-1 The influence of soil moisture, cropping season and species on the Water Use Effiency
(WUE) was displayed as fig. 36. In (fig.36 (I)) the mean for amaranth in 1993 was higher than
in 1992 The same was observed between cropping seasons for quinoa. The value of amaranth
was higher than quinoa in both years. In (fig. 36 (II)) the same was observed between
cropping seasons and species as in (fig. 36 (I)).
The influence of soil moisture treatment, cropping season and species on yield
per plant are displayed as (fig.37). In (fig. 37 (I)) the yield per plant was higher in 1992 than
in 1993 for amaranth while the the opposite was observed for quinoa. In 1992 the value of
amaranth was higher than quinoa while that of quinoa was higher than amaranth in 1993.
In (fig.37 (II)) the amaranth value was higher in 1992 than in 1993, while in quinoa not much
difference was observed between cropping seasons. In 1992 the value for amaranth was
double that of quinoa. In 1993 amaranth was also higher in value but the difference was not
much.
In (fig 35 (I)) the mean of amaranth was calculated from 32.52, 51.36,24.04, 22.41 and 34.65
umol m-2 s-1 taken on the 12th July, 24 July, 03 August, 14 August and 23 August 1992. The
mean for quinoa was from the values 21.88, 44.79, 23.58, 24.39 and 19.91 umol m-2 s-1 also
taken on dates corresponding to those of amaranth in 1992.
In (fig. 35 (I)), 1993, amaranth values were 32.52, 51.36, 24.04, 22. 41 and 34.65 taken on the
12 July, 24 July, 03 August, 14 August and 23 August. The mean for quinoa in (fig. 35 (I))
was calculated from the values 22.46, 44.79, 23.58, 23.11 and 15.67, taken on dates
corresponding to those of amaranth in 1993.
In (fig. 35 (II)), 1992, the amaranth mean was derived from 22.27, 44.16,23.17, 18.76 and
29.63 taken on dates earlier-mentioned for the irrigated amaranth in (fig. 35 (I)). The mean for
quinoa was from the values 17.96, 26.85, 18.78, 22.59 and 14.23 umol m-2 s-1 taken on dates
earlier-mentioned for quinoa in 1992.
In (fig. 35 (II)), the amaranth mean in 1993 had original values of 22.27, 23.17, 18.76 and
29.53 while they were 17.95,26.84, 19.85, 60.81, 21.83 and 14.22 for quinoa during
corresponding measurement dates already mentioned under (fig. 35 (I)).
A comparative histogram presentation between the two years field experiments, 1992 and
1993, are displayed for photosynthesis, water use efficiency and final yield as (fig. 35, 36 and
37) respectively. Analysis of variance of the three attributes between species, soil moisture
and cropping seasons is presented as table 4.
3.2 PHOTOASSIMILATE DISTRIBUTION
During the first harvest analysis of variance (ANOVA) revealed significant differences in the
total radioactivity between species in the top leaves and highly significant differences in the
mid and bottom leaves, flowers and branches of the low soil moisture combination (fig. 6 and
7). Amaranth had higher value than quinoa in all the organs except the flowers and branches.
The high soil moisture combination of the same harvest also revealed highly significant
differences between species in the top, mid and bottom leaves while significant differences
were found in the flowers and petioles. Amaranth had the higher value with respect to the top,
mid and bottom leaves as well as the petioles, while quinoa had the higher value in the
flowers. Non-significant differences were found between species in the stems.
Between soil moisture comparison within species in the first harvest revealed significant
differences in the flowers, stems and petioles as well as the bottom leaves in amaranth. The
high soil moisture combination had the higher values in all the organs except the bottom
leaves. Highly significant differences were found in the top and bottom leaves as well as the
branches in quinoa, while significant differences were found in the stems and petioles. The
high soil moisture combination had the higher values in the branches, stems and bottom
leaves while the low soil moisture combination had the higher value in the top leaves and the
petioles. The remaining organs in quinoa revealed non-significant differences in this form of
comparison.
During the second harvest significant differences were found between species in the top and
middle leaves, while highly significant differences were found in the flowers, stems, petioles
and branches of the low soil moisture combination. Except for the branches amaranth
compared favourably to quinoa in the rest of the organs. In the high soil moisture
combination, comparison between species of the second harvest revealed highly significant
differences in the top, mid and bottom leaves as well as the branches. Amaranth compared
favourably to quinoa in all the organs except in the branches. The flowers and the stems
revealed non-significant differences. Between soil moisture combination in the second
harvest revealed significant differences in all the organs of amaranth except the top leaves and
the flowers. The high soil moisture level had the higher values in all the organs. In quinoa
significant differences were found in the branches, petioles, fallen leaves, top and mid leaves
while highly significant differences were found in the bottom leaves, flowers and stems. The
high soil moisture compared favourably to the low soil moisture in the flowers, stems,
branches and fallen leaves while the low soil moisture combination had the higher values in
the remaining organs. The interaction of the species and soil moisture was found to be highly
significant in the flowers.
The comparison based on harvest revealed significant differences in the top and bottom
leaves, as well as flowers, while mid leaves were highly significant and stems were significant
in the high soil moisture combination of amaranth. Non-significant differences were found in
the petioles. In the cases investigated the second harvest had higher values in the flowers and
the stems, while the first harvest had higher values in the rest of the organs. The top and
bottom leaves, stems, petioles and branches revealed significant differences in the high soil
moisture combination of quinoa while the mid leaves and flowers were found to be highly
significant. The second harvest had the higher values in the top leaves, flowers and stems,
while the first harvest had the higher values in the other organs.
In the low moisture combination between harvests comparison in amaranth revealed
significant differences in the top, mid and bottom leaves as well as flowers and stems while
branches showed high significance. In the top, mid and bottom leaves as well as the branches
the first harvest had the higher values while the second harvest had the higher values in the
flowers and stems. Non-significant differences were found in the petioles. In quinoa
significant differences were recorded in the top, mid and bottom leaves, as well as the
flowers, stems and petioles. The fallen leaves showed a high level of radioactivity while the
branches revealed non-significant differences. In the bottom leaves and the stems the second
harvest had the higher values while in the rest of the organs the first harvest had the higher
values.
3.3 GROWTH ANALYSIS
ASSIMILATORY SURFACE INCREMENT AND BIOMASS
ACCUMULATION
The results of the basic attributes of assimilatory surface increment and biomass accumulation
for 1992 and 1993 cropping seasons showed that leaf area development (fig. 7 and 8)
preceded DM increase. The above-mentioned observation, of leaf area preceding biomass
accumulation, holds in both species for the two years experiments. This was also the case
throughout the stages of development. Chenopodium quinoa was more robust in growth. It
was higher in value of attributes for both the treatments (combinations) and during both
cropping seasons than A. cruentus. Between combinations within species revealed marked
differencies in the value of attributes. The irrigated combination had higher values most of the
time.
ASSIMILATORY SURFACE INCREMENT
In 1992 the ASI curves for both the irrigated and non-irrigated combinations of A. cruentus
(fig. 7(I)) rose steeply between the harvests at 28 and 38 DAE. The differences between the
two curves was very small. Between 38 and 49 DAE the curves were still rising but the
irrigated had higher values. The period between 49 and 59 DAE also revealed rising ASI and
the irrigated still had the higher values. The plants may have benefited from the improved
moisture condition around the 10th of July about 49 DAE. The period between 59 days and 70
DAE revealed a steep rise in the index of the irrigated while that of the non-irrigated was
nearly stable. The irrigated combination may have benefited from the irrigation while the nonirrigated might have been hit by the continued low moisture level. The period between 70 and
79 DAE however revealed a fall in both curves because of the continued low moisture.
Between 79 and 91 DAE both indices rose probably due to the improved moisture. The
irrigated reached its maximum 91 DAE. The period between 91 and 99 DAE therefore
revealed a fall in the index of the irrigated. During the same period the non-irrigated benefited
from the improved moisture condition to increase its assimilatory apparatus. This was shown
by a steep rise in the index.
In 1992 the assimilatory surface curves of the irrigated and non-irrigated combinations of C.
quinoa (fig. 7(II)) rose steeply between 38 and 52 DAE. The plants might have benefited from
the optimum moisture condition around the 10th of July. Between 52 and 61 DAE the curve
of the irrigated combination fell, while that of the non-irrigated was somewhat stable. This
was probably due to the depreciating moisture condition. During the period between 61 and
69 DAE both curves fell steeply. This was also coincidental with depreciating moisture
condition. The period between 69 and 81 DAE revealed a steep rise in the index of the
irrigated while that of the non-irrigated fell. The fall was however markedly lower than the
one recorded during the previous period. During the period between 69 and 81 DAE a rise
was recorded in the Silianinow hydrothermal index (fig. 40). The improved moisture
condition may have been reflected by the indices during that period. The curve of the irrigated
having reached its maximum at the end of the previous period fell steeply, between 81 and 89
DAE. A fall was also recorded in the non-irrigated but the gradient was also lesser than that of
the previous period. The situation might have reflected the improved soil moisture towards
the end of the cropping season. The period between 89 and 102 DAE revealed a further steep
fall in the index of the irrigated while that of the non-irrigated somewhat rose slightly.
In the beginning of 1993 the assimilatory apparatus in both the irrigated and non-irrigated
combinations of A. cruentus (fig. 8(I)) increased between 22 and 42 DAE. The gradients of
the curves were however small. The irrigated had the higher values. The period between 42
and 52 DAE revealed a steep rise in the indices of both combinations. The moisture was
optimum all the time. The rise in the indices continued between 52 and 92 DAE days in the
irrigated combination. The curve having reached its maximum 92 DAE, fell between 92 and
112 DAE, even though the moisture condition was optimum. The non-irrigated curve on the
other hand was rising all the time even when the irrigated fell between 92 and 112 DAE. The
non-irrigated might have benefited from the improved moisture conditions towards the end of
the cropping season. The difference in the values of the indices between the irrigated and the
non-irrigated was increasing rapidly. Between 62 and 92 days when the moisture conditions
were sub-optimal, as indicated by the hydrothermal index, wider differences were revealed
between the irrigated and non-irrigated combinations. During this period the irrigated was
probably benefiting from the provided water to keep most of its leaves intact while the nonirrigated had to shed some of its assimilatory apparatus to minimize transpiration losses.
The irrigated and non-irrigated assimilatory surface increment curves of C. quinoa during the
1993 cropping season, were overlapping during the period between 22 and 32 DAE. The
moisture was optimum by then and there was little difference between the irrigated and the
non-irrigated. The next period between 32 and 42 DAE revealed a divergence of the curves
with the irrigated having the higher value 42 DAE. After the local maximum the irrigated
dropped suddenly to a local minimum 52 DAE. By then the non-irrigated rose. This may be
due to the elevated moisture during this period. The non-irrigated which was frequently
subjected to temporary wilting may have tremendously benefited from the elevated moisture
while the irrigated, which had little or no low moisture effects, negatively reacted. The period
between 52 and 62 DAE revealed a steep rise in the index of the irrigated. The moisture was
falling by then. The level may have been optimum for the irrigated combination. At the same
time the curve of the non-irrigated also rose. During the period between 62 and 92 DAE both
curves were rising. The depreciating moisture during the period 72 and 82 DAE did not cause
a fall in the curves of both combinations. This may have been due to the fact that the plants
were able to use the large assimilatory apparatus earlier-acquired to add more to its
assimilatory surface. Both curves fell steeply between 92 and 102 DAE .
DYNAMICS OF BIOMASS ACCUMULATION
The dynamics of biomass accumulation results are displayed as (fig. 9 and 10). In 1992, (fig.
9), the curves differ in both species and combinations. Amaranthus cruentus was sown two
weeks before C. quinoa. The dynamics of biomass accumulation was however more
pronounced in C. quinoa than in A. cruentus. The climatic conditions in 1992 after A.
cruentus were sown on the 18th of May 1992 was such that several rainless days followed. It
was not condusive for robustness in growth. Chenopodium quinoa was sown on the 2nd of
June 1992. It had a good start with respect to moisture conditions. The hydrothermal index
was greater than unity before sowing. The necessary conditions of optimum soil moisture for
germination were assured.
The Amaranthus cruentus aspect of the dynamics observation showed that until 91 DAE, the
two combinations were increasing all the time. The irrigated curve dropped down after 91
DAE and continued dropping right on to 99 DAE. On the other hand the non-irrigated curve
continued to rise. During the 1992 cropping season the two combinations of C. quinoa were
following a similar trend up to 59 DAE, the non-irrigated fell while the gradient of the
irrigated curve which had started reducing in the previous period continued until 70 DAE.
After that the two curves swiftly continued to rise until the 91DAE when ontogeny caught up
with the irrigated combination. The non-irrigated combination on the other hand was rising all
the time.
In 1993, (fig. 10), the course of A. cruentus dynamics curve was similar in both combinations,
in that the curves were rising all the time. The same situation was observed in C. quinoa. In
both crops, the non-irrigated combination had lower values throughout the cropping season
though the difference was more marked in quinoa.
RGR
The relative growth rate curve (RGR), henceforth refering to whole plant, in A. cruentus (fig.
11(I)) initially fell. The situation could be attributed to the low precipitation that preceded the
second harvest 38 DAE. Only once did the hydrothermal index was above unity. The curve
rose with a somewhat minimal gradient from 49 DAE to 59 DAE. The situation might be due
to two reasons. One reason might be the second fertilizer application about 58 DAE. The
fertilizer application was accompanied by weeding and second thinning which led to aeration
of the soil and improvement in the soil structure. It might also be due to the brief
improvement in moisture condition before the 3rd harvest as manifested by the increased
hydrothermal index. After 59 days after emergence the RGR curve fell again. Among other
things the low moisture level as manifested by the hydrothermal index which was below 0.5
might have been a prominent reason. Equally important was the appearance of inflorescence
during the 70 days after emergence. These generative organs are stronger acceptors of
photoassimilates than branches. The branches also manifested a reduction in their contribution
to RGR. A situation that made things worse as branches are supposed to be assurances against
stressful situations. The stagnation of the curve, between 70 and 79 DAE respectively, may be
due to the improved moisture condition as indicated by the hydrothermal index. The relative
lack of importance of the contribution of branches to RGR was manifested between 70 and 79
DAE. Notwithstanding the reduction of the contribution of the branches, the RGR was steady.
The index rose again after 79 DAE. The rise may be attributed to improved weather condition
manifested by the hydrothermal index which rose and almost reached the 6th grade. The
temperature also reduced after increasing around 94 DAE. The contribution of all the organs
except the petioles to RGR was remarkable. After 91 DAE harvest ontogenetic drift caught up
with the index.
The situation in the non-irrigated combination of A. cruentus (fig. 11(II)) was somewhat
different. The idex fell down to 0.04 while in the irrigated combination it was above 0.1 a
situation that reflected the stressing moisture condition as manifested by the hydrothermal
index which for most of the time was less than unity before 49 DAE. It is not surprising that
the intensity of the stress on RGR was such that the branches which are generally considered
assurances against stressful conditions started appearing during this harvest, while branches
did not appear in the irrigated combination until 59 days after emergence. It should be noted
that the percentage contribution of the branches in A. cruentus, in general, is small unlike C.
quinoa as shown in (fig. 12 and 14). The contribution of the branches to RGR slightly
increased 79 days after emergence to almost 0.3. In the case of the irrigated combination the
appearance and development of the generative organs during the period between 70 and 79
DAE coincided with leveling in RGR curve and also marked reduction of the contribution of
the branches was observed. During this same period in the non-irrigated combination an
increase in the index was the case. This increase coincided with an increase in the
contribution of the branches notwithstanding the appearance and development of the
generative organs. This fact may lend credence to the further fact that the contribution of the
branches was very important in RGR for the non-irrigated combination. The irrigated
combination was in a better position to avoid the hazards of temporary wilting while the nonirrigated combination was constantly subjected to it.
The index fell during 91 DAE. The appearance of the seeds and the reduction in the
contribution of the inflorescence might have been implicated in the phenomenon. The
branches on the other hand took advantage of the improved weather condition to add to its
enormous biomass realized 79 DAE. The rainfall reached its maximum value of about 78mm
around this harvest. The beneficial effects of the improved moisture condition 91 DAE were
manifested 99 DAE. The contribution of the maturing seeds, the leaves and the stems to the
increased RGR rather made trivial the reduction in the contribution of the branches,
inflorescence, and petioles. This situation was very much opposite to the irrigated
combination when the contribution of all the organs reduced and in turn resulted in the fall of
the index.
The index for the irrigated combination of C. quinoa in 1992 fell 61DAE, (fig. 12(I)). The
precipitation was low at the time of the harvest. It also coincided with the formation of
inflorescence which are stronger acceptors. They developed at a faster rate right on to 69
DAE at the expense of RGR which reached a local minimum. The index however rose again
to a local maximum 81 DAE as a result of the improving moisture condition. After that
harvest ontogeny dictated in the decrease of all the organs.
The 1992 RGR for the non-irrigated combination of C. quinoa (fig. 12(II)) dropped from 0.1
in the second harvest. The appearance of the inflorescences and the poor moisture condition
might have caused the decrease in the index. The decrease continued and reached its lowest
value 69 DAE. The index again started to rise with the improvement in moisture condition
around 81 DAE. The contribution of all the organs to RGR except the inflorescence increased.
After the fifth harvest the index was somewhat stable thanks to the improved rainfall
condition. It should be added that the index underwent little variation in its course.
In 1993 the RGR curve (fig. 13(I)) of the irrigated combination of A. cruentus started by
falling. The situation might not be unconnected with low precipitation around 11DAE. After
42 DAE the curve rose again probably due to improved rainfall condition as manifested by a
high hydrothermal index for the better part of late June preceding the harvest on the 12th of
July, 52 DAE.
The harvest on the 22 of July, 62 DAE reavealed a fall in the RGR. The contribution of all the
organs to RGR fell. The next harvest 72 DAE revealed a rise in RGR. This may be due to
optimum moisture condition. Even the appearance of stronger acceptors as the inflorescences
did not cause a reduction in RGR. The next harvest 82 DAE revealed a fall in the index. This
phenomenon might not be unconnected with the continued depreciation of the moisture
condition. The harvest on the 21st August 92 DAE revealed RGR reaching a local maximum.
This may be attributed to improved moisture condition. After that harvest ontogenetic drift
caused the fall of the index. The harvests at 102 and the last at 112 DAE all recorded a fall in
RGR.
The non-irrigated combination of A. cruentus (fig. 13(II)) rose after the second harvest 32
DAE apparently taking advantage of the condusive moisture condition. After 32 DAE the
index was still rising infact reaching its maximum value 52 DAE. Indeed the hydrothermal
index reached the maximum value of over 2.8 around 52 DAE after that the index started to
fall. The fall recorded 62 DAE might be due to the depreciative moisture condition as
manifested by the falling hydrothermal index before the harvest. The contribution of the
branches to RGR during the 6th harvest, 92 DAE, was two folds. First, the branches were
about 38% of the total DM of plant (fig.23 (II)). Futhermore the fresh assimilatory surface of
branches provided improvement in net assimilation which in turn improved biomass
accumulation. The contribution of the branches to the RGR 72 DAE outweighed the effect of
the depreciating moisture condition which was clearly shown by the hydrothermal index. The
said contribution of the branches also made trivial the negative effect of the appearance of the
inflorescences which is usually reflected on RGR. Anyway the harvest at 82 DAE revealed
the negative effect that the continued depreciating moisture condition had on RGR. Indeed the
contribution of all the organs was affected. The 8th harvest, 92 DAE, revealed improvement
in RGR, which reflected the improving moisture condition. Indeed the index reached a local
maximum after that ontogenetic drift caught up with the index.
The RGR for the irrigated combination of C. quinoa in 1993 figure 14(I) started by falling. It
was all the time falling. Even the condusive conditions of growth and development existing
during the 4th harvest, 52 DAE, did not stop the index from falling. Improved moisture
conditions are sometimes accompanied by an improvement in RGR. Probably the appearance
of inflorences coupled with depriciating moisture conditions caused the reduction in RGR 72
and 82 DAE. In the 8th harvest, 92 DAE, when ontogentic drift had already caught up with
the index not even the gain manifested by the contribution of the leaves coupled with
improved moisture conditions remedied the downfall of the index.
In 1993 the RGR for the non-irrigated combination of C. quinoa (fig. 14(II))
initially rose after the 2nd harvest 32 DAE. This may be due to the contribution of the leaves.
The moisture condition was also favourable. The crops utilized the condusive moisture
condition in further raising the index 42 DAE. In the 4th harvest, 52 DAE, utilization of the
increased rainfall resource was also manifested through the rise in RGR. The 5th harvest, 62
DAE, revealed a reduction in the index which might have been a reflection of the depreciating
moisture condition. The 6th and 7th harvests, 72 and 82 DAE respectively revealed a
continued fall in the index as verification of the depreciating moisture condition. The 8th
harvest, 92 DAE, revealed a local maximum probably reflecting the improvement in moisture,
before the setting of ontogenetic drift during the 9th harvest, 102 DAE.
ULR
The 1992 ULR for the irrigated combination of A. cruentus initially fell (fig. 15(I)) between
the 2nd and the 3rd harvests 38 and 49 DAE. The non-irrigated combination also followed the
same trend. This may be due to the difficulty of crop establisment as a result of moisture
stress earlier-mentioned in section 2.3 of the methodology. Only once around 12 DAE, did the
hydrothermal index reached unity. The curves for the two combinations rose between 49 and
59 DAE. The two curves merged 59 DAE. The reason for the rise in the curve when the
moisture condition around the harvest 49 and 59 DAE was depreciating might be associated
with robustness in growth and development after the second fertilizer application 55 DAE.
The continued moisture stress beyond 59 DAE out-weighed earlier positive effects of the
fertilizer application and so the curve fell steeply in both combinations with the irrigated
reaching a local minimum value 70 DAE which was lower than the minimun of the nonirrigated combination. The curve for the irrigated combination did not change 79 DAE, while
that for the non-irrigated rose to a local maximum. It is possible that 79 DAE witnessed the
threshold to improvement in the moisture regime. Indeed the next harvest revealed a
tremendous rise in the curve of the irrigated combination which reached its maximum before
the onset of ontogenetic drift. The non-irrigated combination however fell slightly 91 DAE
but rose steeply again 99 DAE, obviously taking advantage of the improved moisture regime
around 101.
The rise in the index of the non-irrigated combination 99 DAE was significant. In most crops
ontogeny might have caught up with the index. A. cruentus has the specific characteristic of
possessing lots of green leaves during the late vegetative season. The said leaves are usually
as efficient in assimilation as those during earlier stages of development.
The ULR in the irrigated combination of C. quinoa in 1992, (fig. 15(II)) fell between 52 to 61
DAE. The rise of the curve by the non-irrigated combination during the same period was also
somewhat not clearly defined, with a gradient that is minimal. The situation might have
reflected the low moisture regime during the period between the last decade of July, around
70 DAE and the end of the first decade of August, after 79 DAE. Indeed to substantiate the
claim that waterlessness was a major factor in the poor showing of the index, both curves
dropped during the period 61 and 69 DAE. During that period the hydrothermal index was
below 0.5, signifying too little water for growth and developmental processes. After that, the
period between 69 and 81 DAE revealed increases in both curves. The significance of the rise
was in the steepness. The non-irrigated combination was rising from its lowest point. The rise
coincided with the time in which the moisture regime started to improve during the second
decade of August , around 80 DAE. During the period between 81 and 89 DAE the curve of
the irrigated fell while that of the non-irrigated rose. The same trend continued during the
period between 89 and 102 DAE. A plausible reason for the trend might be that 81 DAE the
curve of the irrigated combination attained its highest level after which ontogeny caught up
with it. It is possible that by that time the non-irrigated combination was benifiting from the
high moisture level during the last decade of August, around 95 DAE and the first decade of
september to optimize its growth and developmental processes, which were not fully realized
during earlier stages of growth because of moisture stress experienced in 1992.
In 1993 the curve of the irrigated combination of A. cruentus fell (fig. 16(I)) during the period
between 32 and 42 DAE. By then the curve of the non-irrigated combination was rising,
reaching a local maximum 52 DAE. During the period 42 to 52 DAE the curve of the irrigated
combination also rose. The improved moisture condition during the period between the 1st
and 2nd decades of July, around 50 DAE might have in turn caused the improvement in ULR.
Between 52 and 62 DAE the curve again fell. The moisture regime during the second decade
corresponding to the period when the curves fell, was depreciating it is therefore plausible to
suggest a cause and effect relationship. The curves again rose after 62 DAE. It is possible that
the appearance of the generative organ, the inflorescence, may have put a high premium on
the index. Indeed the curves reached their peaks 72 DAE. However, probably because of
continious depreciation of the moisture regime, the curves fell between 72 to 82 DAE. When
the moisture regime again improved during the period between 82 and 92 DAE, the curves
again rose steeply. While the curve for the irrigated combination continued rising during the
next period between 92 and 102 DAE, ontogeny caught up with the non-irrigated
combination. Ontogenetic drift caught up with the irrigated combination after the harvest on
the 21st August, 102 DAE.
In 1993 the ULR for the irrigated combination of C. quinoa (fig. 16(II)) was initially stable
during the period between 32 and 42 DAE. The curve for the non-irrigated combination rose
during the same period. The plants might have benefited from the conducive moisture
condition prevalent at the time. The next period between 42 and 52 DAE revealed a rise in the
curve for the irrigated combination and a further rise in the curve for the non-irrigated
combination infact reaching its maximum 52 DAE. The non-irrigated unlike the irrigated
combination tremendously benefited from the favorable moisture regime prevalent during this
period. The ULR of the irrigated combination might have depreciated due to having an
enormous non-assimilatory fraction, which put a heavy load on the assimilatory fraction.
During the period between 52 and 62 DAE ULR of irrigated plants was increasing while that
of the non-irrigated ones was falling. The period between 62 and 72 DAE revealed a rise in
the index for both combinations. This may be due to the appearance of the inflorescences,
which usually put a high premium on the ULR. The next period between 72 and 82 DAE
revealed arise in both combinations. During the period between 82 and 92 DAE the curve of
the irrigated combination fell steeply suggesting the on-set of ontogeny. The non-irrigated
combination on the other hand rose to a local maximum 92 DAE before the on-set of
ontogeny. It may have benefited from the favourable moisture condition. Despite the
favorable moisture condition during the period between 92 and 102 DAE the non-irrigated
combination dropped while the irrigated combination rose. In both cases ontogeny was the
most plausible reason.
LWR
In 1992 the LWR curves (fig. 17(I)) for the irrigated and non-irrigated combinations of A.
cruentus were similar in their course. They were inversely proportional to time. They were
subjected to ontogeny. The values of the non-irrigated combination were higher at 49, 59, 91
and 99 DAE. The curves for the irrigated and non-irrigated combinations of C. quinoa in 1992
(fig 17(II)) also showed the same ontogenetic tendency as in the case of A. cruentus. The
main difference was that in the case of C. quinoa the non-irrigated combination had higher
values throughout.
In 1993 LWR (fig. 18) was also not very dissimilar in its course in both species and
combinations to that in 1992. First, like in 1992 the index was subjected to ontogenetic drift in
both combinations and species. Secondly the non-irrigated combination was higher in values
during most harvests in both species. It is possible that the greater contribution of the nonassimilatory organs, like the stems, in the irrigated treatment might be due to preparation for
carrying the relatively heavier assimilatory and generative organs. It should not go without
observation that even when the irrigated had higher values like in the case of C. quinoa in
1992, this situation was only temporary and was later inverted. This may suggest that the
addition of biomass to the non-assimilatory organs, like the stem, might have been necessary
in preparation for the heavy assimilatory and generative organs which they had to carry.
In the case of A. cruentus a C4 species, the range of the values of LWR was somewhat similar
in both combinations and years, fetching between 0.1 and 0.75. In C. quinoa, a C3 species
characterized by its relatively heavier dependence on water, the situation was markedly
different. The LWR was markedly dissimilar between the two years which may be due to
tremendous differences in moisture condition. The index fetched values between 0.03 and
0.27 in 1992 while in 1993 the range was between 0 and 0.65. In 1993 the relatively favorable
moisture condition might have been benefited from by both combinations in realizing higher
values of the index.
SLA
In 1992 SLA for the irrigated combination A. cruentus initially fell, (fig 19(I)), reaching its
minimum, 70 days after emergence before it started to rise again. The non-irrigated
combination on the other hand initially rose reaching a local maximum 49 days after
emergence before falling gently to a minimum 91 days after emergence. The curves of both
combinations did not vary widely during the course of the cropping season. This observation
is normal. The fact that the curve of the non-irrigated combination was for most times higher
in value may not be unconnected with the further fact that irrigation promoted higher biomass
accumulation. In 1992 the SLA of C. quinoa, (fig. 19(II)) did not vary much in both
combinations. The lowest values for the irrigated and the non-irrigated combinations were in
the 4th harvest 69 DAE. This might have reflected the waterlessness that had being
prevailing. The fact that the index for the irrigated combination was higher 61, 69 and 81
DAE may be due to the appearance of many new leaves that were thinner due to constant
irrigation.
The SLA indices for the irrigated and non-irrigated combinations of A. cruentus in 1993,
figure 20(I), initially dropped steeply. Beyond 42 DAE they did not vary much right through
to the end of the cropping season. The moisture regime was comparatively better than in
1992. This might be the reason why an inversion of the 1992 situation, with the irrigated
having higher values for most of the time, was the case. The sufficiency in rainfall was
somewhat benefited from by both combinations by way of biomass accumulation. The
additional irrigation might have caused the higher assimilatory surface area values in the
irrigated combination. The higher quotients (SLA) were then justified in accordance with the
formula in section 2.3 of chapter two.
In the two combinations of C. quinoa in 1993, (fig. 20(II)), the SLA curves were rising all the
time. The obvious variation in the course of the index during the cropping season might be
attributed to the favourable moisture condition in 1993. The irrigated combination had higher
values for the better part of the cropping season. This might be attributed to the increase in
assimilatory surface area due to the improved moisture condition.
LAR
The courses of the leaf area ratio (LAR), which is the product of the SLA and LWR, for the
two years of field experiment 1992 and 1993, are displayed as (fig 33 and 34) respectively. In
(fig. 33 (I) and (II)) both curves fell implying an inverse relationship with time. In general the
non irrigated had the higher values.
In (fig. 34 (I)) the relationship also implies indirect variation between DAE and LAR,
between 72 and 112 DAE the irrigated treatment had the higher values. In (fig. 34 (II))
inverse variation was also shown but the non-irrigated had higher values.
Percentage contribution of organs
In 1992 and 1993 the contribution of the leaves to the dry matter (DM) was initially very high
in both the irrigated and the non-irrigated combinations of A. cruentus, (fig. 21 and 23)
respectively. The contribution of the non-assimilatory organs was relatively smaller. The
assimilatory apparatus systematically decreased as the cropping season proceeded while the
other non-assimilatory organs, like the inflorescence and seeds, which were produced during
late development increased their contribution. The stems, generally, displayed a monomodal
type of curve. Initially its contribution was small it later increased its contribution towards the
middle of the cropping season. This may be in preparation of having to carry a heavy load of
both assimilatory and generative organs. Its contribution however declined towards the end of
the cropping season when the generative organs increased.
In C. quinoa, two distinct patterns of percentage contribution of organs to DM based on
cropping season were observed. In 1992, (fig. 22), which was drier the contribution of the
leaves, petioles and the branches as assimilatory organs was relatively smaller than the
contribution of the stems. In 1993, (fig. 24), the situation was a reversal of the 1992
observation. In both patterns, systematic decrease of the percentage contribution of the
assimilatory apparatus with an increase in the percentage contribution of the generative
organs was observed. The stems revealed the same progress as in A. cruentus. The observed
decreased percentage contribution of the assimilatory surface in C. quinoa in 1992 may be
due to the strategy of evading excessive transpiration losses. The reduced percentage
contribution may have been at the benefit of the roots. Usually when a resource is limited, in
the case of 1992 it was moisture, the organ that is charged with the function of supplying that
resource will increase its development and growth relative to the others, inorder to meet the
needs of the plant in that resource.
Crop Growth Rate (CGR)
The CGR for the irrigated combination of A. cruentus during the 1992 cropping season (fig
25(I)) rose from the second harvest 38 DAE. During the same period the non-irrigated
combination curve was stable. The succeeding period between 49 and 59 DAE revealed a
steep rise in both curves. This may not be unconnected with the improved moisture condition.
Both curves reached local maxima 59 days after emergence with the irrigated combination
having the higher value. The period between 59 and 70 DAE revealed a steep fall in the
curves. This period corresponded with depreciating moisture condition. Indeed the nonirrigated combination reached its minimum at the end of this period. The next period between
70 and 79 DAE revealed stability in the curve of the irrigated combination while the nonirrigated curve made a somewhat slight upward rise. There was a slight improvement in the
moisture but this was not benefited from immidiately probably due to the fact that
inflorescence appeared 70 DAE. The appearance of these non-assimilatory stronger acceptors
during this period might have led to the retardation in growth of the other organs that are
primary producers like the leaves, branches and petioles. During the period 79 and 91, the
index of the irrigated combination again rose steeply while that of the non-irrigated was
stable. The irrigated combination obviously led in benefiting from the improved moisture
condition which reached a maximum at the end of this period. The non-irrigated combination
might have had the added problem of coping with seed development. This might have caused
the delay in its response to the improved moisture during this period. Indeed the seeds
appeared 91 DAE. The development of the seeds which are non-photosynthesizing might
have led to lateness in response to the improved moisture by other assimilatory organs in the
non-irrigated combination. In the irrigated combination the situation was different due to
mentainance of stability through constant irrigation. The irrigated combination having reached
its maximum 91 DAE fell steeply to as low as -32 g g-1 day-1 during the last harvest 99 DAE.
It was during this same period that the non-irrigated combination then benefited from the
improved moisture. This was shown by the steep rise of its curve to a maximum.
The CGR for the irrigated combination of C. quinoa in 1992 (fig. 25(II)) declined during the
period between 52 and 61 DAE while the non-irrigated rose with a somewhat small gradient.
The situation might be a reflection of the depreciating moisture condition. To substantiate this
claim both curves declined during the period 61 and 69 DAE with the non-irrigated reaching
its minimum. Furthermore the development of inflorescence in the buds might have added to
the low moisture effect during this period. Indeed the inflorescence appeared 61 DAE. The
following period between 69 and 81 DAE revealed a rise in the index in both combinations.
This may be due to the fact that the improving moisture condition led in turn to an increase in
the contribution of the assimilatory apparatus. This fact was manifested by the increased
contribution of the leaves branches and petioles to RGR. During the period 81 and 89 DAE
the curve of the irrigated combination fell while that of the non-irrigated combination rose
with a small gradient. The non-irrigated combination may have benefited from the improved
moisture. The irrigated on the other hand may have benefited from irrigation and reached its
maximum 81 DAE. Until the time when strong winds blew down the plants 102 DAE. By
then CGR in the irrigated combination was still falling while it was still rising in the nonirrigated combination.
In 1993 the CGR in the irrigated combination of A. cruentus (fig. 26(I)) during the period
between 32 and 42 DAE somewhat rose with an almost indiscernible gradient. The gradient of
the curve of the non-irrigated combination was also small. During the period between 42 and
52 DAE, both curves rose. The contribution of the assimilatory apparatus in the form of the
leaves and petioles increased as manifested by the RGR curve. The successive period between
52 and 62 DAE revealed stability in both curves. This situation may have been caused by the
decrease in the contribution of the assimilatory apparatus as indicated by the RGR curves (fig.
13). Indeed the period between 62 and 72 DAE revealed a rise in both CGR and the
contribution of the assimilatory apparatus as indicated by RGR. The irrigated combination
had the higher value in CGR, infact reaching a local maximum at the end of this period. This
period also recorded a hydrothermal index, on the average, of about 0.6. The significance of
this fact to the growth characteristics lies in the further fact that the reduction of the moisture
relative to the previous period may have led to field capacity moisture around the root zone.
The generative organ, the inflorescence, also appeared at the end of this period.
Notwithstanding the appearance of these strong non-assimilatory organ CGR rose in both
combinations. This may have indicated that soil moisture was optimum. However with
decreasing moisture level during the period between 72 and 82 DAE, CGR dropped. The
contribution of the assimilatory apparatus also dropped, suggesting that it might have caused
the drop in CGR.
The next period, 82 to 92 DAE, revealed a rise in the index in both combinations with the
non-irrigated having the higher value. The situation may have reflected the improving
moisture condition. The higher value manifested by the non-irrigated combination may be
more clearly understood from the point of view of the increasing contribution of the branches.
It should be noted that in the non-irrigated combination notwithstanding the fall in the
contribution of the leaves to RGR, the index still rose. This might have been due to the fact
that the branches played a leading role in the assimilatory apparatus. The following period
between 92 to 102 DAE, the index of the irrigated combination rose while that of the nonirrigated fell steeply. The development of the seeds may have caused the drop in the index in
the non-irrigated combination, while the irrigated benefited from the subsidized irrigation to
increase its RGR. Indeed the seeds appeared at the end of this period. The period between 102
and 112 DAE revealed a fall in the index of the irrigated while that of the non-irrigated
combination rose. The irrigated curve fell probably because the index had reached its
maximum while the non-irrigated combination benefited from the improved moisture
condition.
The CGR of the irrigated combination of C. quinoa during the 1993 cropping season (fig.
26(II)) rose initially during the period within 32 and 42 DAE. The same was recorded for the
non-irrigated combination. The irrigated combination had higher values. The same upward
trend was recorded for the period between 42 and 52 DAE. During the period 52 and 62 DAE,
CGR of the irrigated combination rose while that of the non-irrigated combination fell with a
somewhat small gradient. The next period between 62 and 72 days after emergence revealed a
further steep rise in the index of the irrigated combination while that of the non-irrigated rose
with a small gradient. The successive period between 72 and 82 DAE revealed a further rise
in the index of the irrigated combination while the index of the non-irrigated fell slightly. This
may be due to low moisture level as indicated by the falling hydrothermal index. The
development of the seeds which indeed appeared at the end of this period may have
compounded the low moisture problem in the non-irrigated combination while the irrigated
was late to respond due to irrigation. The period between 82 and 92 DAE revealed a fall in the
index of the irrigated combination. The situation might be due to the on-set of ontogeny. The
contribution of the assimilatory apparatus was of little importance as the organs involved were
probably too old to be efficient enough. This claim was substantiated by the ULR curve which
dropped steeply. The CGR curve for the non-irrigated treatment rose during this period
probably due to beneficial effects of the improved moisture condition. At the end of this
period ontogeny also caused a drop in the index.
Unit Leaf Rate of canopy (ULRc)
The ULRc of the irrigated combination of A. cruentus in 1992, (fig. 27(I)), fell during the
period between 38 and 49 days after emergence. The same progress was recorded for the nonirrigated combination. Although both curves fell to local minima that of the irrigated
combination was higher in value at the end of the period under review. The fall in both curves
was a reflection of the low moisture condition initially encountered at the beginning of the
cropping season. The period between 49 and 59 DAE revealed a rise in the indices of both
combinations. The crops may have had a belated response to the improved moisture
condition. However with increasing depreciation in moisture, both curves fell again between
59 and 70 DAE, with the irrigated having the least value at the end of the period. The
successive period between 70 and 79 DAE revealed a rise in the curve of the non-irrigated
while that of the irrigated was stable. Due to improved moisture condition during the period
79 and 91 DAE, the ULRc of the irrigated combination rose markedly. The non-irrigated
combination however failed to show an early start in benefiting from the improved moisture
condition. The ULRc of the irrigated combination having reached its maximum at the end of
the period, started falling while the non-irrigated started to rise. The non-irrigated might have
shown signs of a belated response to the improved moisture condition.
The ULRc of the irrigated combination of C. quinoa in 1992, (fig. 27(II)) started by falling
during the period 52 and 61 DAE while that of the non-irrigated rose with a somewhat small
gradient. Indeed the next phase between 61 and 69 DAE clearly showed the negative effects
of the low moisture level at the beginning of the cropping season. Both curves fell with the
non-irrigated reaching its minimum value at the end of the period. During the next period
between 69 and 81 DAE the indices of both combinations rose steeply. This may have been
due to the improved moisture condition. The next period between 81 and 89 DAE the curve of
the irrigated fell steeply after reaching a maximum, at the same time that of the non-irrigated
rose. The irrigated combination may have reached its maturity while the non-irrigated
benefited from the improved moisture condition.
The ULRc of Amaranth in 1993 followed the same pattern independent of soil moisture
treatment. The maximum value attained at 72 DAE was about 12 for the non-irrigated, while
that of the irrigated was about 10 g g-1 day-1. The only significant difference between both
treatments was after 82 DAE. The values for the irrigated plants displayed diverse time
course, reaching 2 at the end of the experiment, while in the non-irrigated treatment it was
more than 6.
ULRc of the irrigated quinoa started at 8 g g-1 day-1 32 DAE and stabilized between 62 and 82
DAE and it reached a maximum of 9,42 DAE. Non-irrigated plants of quinoa sharply
increased their ULRc during 32 and 52 DAE. They reached maximum of about 10,5 g g-1 day1
52 DAE, but steeply decreased to about 4 82 DAE, probably following an abundance of
rainfall (see Selyaninov index). Nevertheless the subsequent drop of ULRc in the treatment
resulted in values of the index below 2 g g-1 day-1.
Leaf Area Index (LAI)
The LAI of A. cruentus of both the irrigated and non-irrigated combinations in 1992, (fig
29(I)) was rising between 38 and 70 DAE. Later probably due to senescence and abscission of
older leaves which were replaced by smaller and younger leaves due to reduced moisture
level the curve dropped slightly between 70 and 79 DAE for the non-irrigated combination
and was stable for the irrigated combination. The curve again rose in the irrigated
combination between 79 and 91 DAE at the same time the curve of the non-irrigated
combination remained stable. Later between 91 and 99 DAE both curves rose with the nonirrigated having the steeper gradient. It may have followed in benefiting from the improved
moisture condition. The irrigated combination curve already started to rise during the earlier
period between 79 and 91 DAE. The fact that LAI rose between 91 and 99 DAE was
significant in the sense that the tendency of A. cruentus to keep green leaves even when most
of the seeds are matured and ready for harvest was exhibited.
The LAI for C. quinoa in both the irrigated and non-irrigated combinations in 1992 (fig.
29(II)) initially rose between 52 and 61 DAE. Both combinations had maximum values 61
DAE. The continued depreciation of the moisture condition caused a fall in the indices
between 61 and 69 DAE. The unfavourable moisture led to further decrease in the index of
the non-irrigated while the irrigated rose between 69 and 81 DAE. The differences between
combinations may be due to the fact that the irrigated was receiving additional moisture.
Between 81 and 89 DAE the same trend as in the previous period continued although the nonirrigated somewhat had a gradient that was smaller than that of the previous period. Indeed
the period between 89 and 102 DAE almost failed to reveal any fall in the index of the nonirrigated, probably due to the fact that the plants responded to the improvement in moisture.
The irrigated on the other hand fell probably due to ontogeny.
In 1993 the index of the irrigated combination of A. cruentus, (fig. 30(I)) rose right through to
its maximum value 102 DAE before it fell due to ontogeny. The index of the non-irrigated
also rose though with lesser values relative to those of the irrigated. The index of the non-
irrigated might have shown that the plants benefited from the improved moisture at the end of
the cropping season. Proof of this was in the fact that even when the index of the irrigated fell
that of the non-irrigated rose between 102 and 112 DAE. The curve of LAI (fig. 30(II)) of the
irrigated combination of C. quinoa rose right through to the last harvest 102 DAE. The nonirrigated combination also followed the same trend, though with lesser values, right through to
the 8th harvest 92 DAE. After that harvest the index fell slightly 102 DAE.
It should be noted that the LAI of both combinations and species during most harvests was
increasing. Except for the 1992 C. quinoa, (fig. 29(II)), most combinations had values greater
than five which falls within the expected norms for temperate crops.In (Fig. 31 and 32) the
leaf area duration (LAD) for the two combinations and species during the two cropping
seasons 1992 and 1993 respectively are displayed. Chenopodium quinoa had higher values in
both combinations than A. cruentus in 1993 but lesser in both combinations in 1992. This
observation probably underlines the importance of water to C3 carboxylation pathway plants.
Indeed in 1993 the moisture conditions were better than in 1992 hence the better showing in
the index for C. quinoa, a C3 pathway plant, in 1993 than in 1992.
Harvest Index (HI)
The means of A. cruentus in both combinations in the 1992 plot experiment were 0.19 and
0.36 for the irrigated and non-irrigated combinations respectively. While they were 0.16 and
0.19 in 1993 in the same order as in 1992. The means for C. quinoa were 0.19 and 0.16 in
1992 for the irrigated and non-irrigated combinations respectively. While they were 0.16 and
0.19 in 1993 in the same order as in 1992. It is timely for ease of comparison to include the HI
results for the pot experiment in 1992. The A. cruentus means were 0.46 and 0.48 for the high
and low soil moisture levels respectively while they were 0.57 and 0.48 for C. quinoa in the
same respective order as for amaranth.
Analysis of variance (ANOVA) revealed highly significant differences between species,
combinations and their interaction in the HI of the 1992 and 1993 plot experiments. In 1992
A. cruentus had the higher value of 0.29 while C. quinoa had 0.19 with LSD equal 0.01. The
non-irrigated combination had the higher value of 0.29 while the irrigated had 0.19 with LSD
equal 0.01. In 1993 the 0.18 mean of A. cruentus compared favourably to the 0.13 value of C.
quinoa with LSD equal 0.01. It should be noted that with respect to 1993 the 0.18 value of the
irrigated combination compared favourably to the 0.13 value of the non-irrigated
combination. The least significant difference (LSD) was 0.01. This was contrasting to the
1992 results. Comparison between cropping seasons revealed significant differences. The 0.23
mean of 1992 compared favourably to the 0.16 value of 1993 with LSD equal to 0.06.
Comparison between plot and potted experiments in 1992 were based on the two moisture
levels. The results of the high moisture level combination of the pot experiment were
compared with the irrigated combination of the plot experiment. Highly significant
differences were found between species while significant differences were found between
experiments (plot x pot) and the interaction of the two factors. The mean of A. cruentus was
0.18 while that of C. quinoa 0.52. The plot experiment had a mean of 0.33 and that of the pot
0.38. The least significant difference (LSD) was 0.04 in both cases.
Analysis of variance (ANOVA) was also carried out between the low moisture combination
of the pot experiment and the non-irrigated combination of the plot experiment in 1992. It
revealed highly significant differences between species, experiments (plot versus pot) and
their interaction. The mean of A. cruentus was 0.49 while it was 0.29 for C. quinoa. The mean
of the plotted experiment was 0.29 while that of the potted was 0.49. The LSD in both cases
was 0.01.
It should not pass without observation that specific differences depend on the moisture level.
When the high moisture level combination was compared with the irrigated combination the
mean of C. quinoa (C3 plant) compared favourably to the mean of A. cruentus (C4 plant). On
the other hand, when the low moisture combination of the pot experiment was compared with
the non-irrigated combination A. cruentus compared favourably to C. quinoa. This further
underlines the relatively higher water use efficiency (WUE) of A. cruentus (C4). The
differences in the level of significance between the experiments and their interactions is also
worthy of notice.
MINERAL RELATION
CRUDE PROTEIN (CP)
In 1992 comparison between species for the irrigated treatment of the first harvest (tables 14
and 15), revealed that amaranth had the higher value for branches while quinoa compared
favourably in the leaves and seeds. Between species comparison, for the non-irrigated
treatments, revealed that quinoa had the higher values for all the organs.
The second harvest revealed that the irrigated quinoa had the higher value of leaves but
amaranth was observed to have higher ones for the branches and seeds. The non-irrigated
treatment of the second harvest revealed that quinoa compared favourably in the case of the
leaves, seeds and stems while amaranth had the higher values for branches.
Between soil moisture treatments comparison, (table 14) in 1992 for the first harvest revealed
that the non-irrigated had the higher value for % CP while the second harvest revealed that
they compared favourably in the branches leaves and stems.
In (table 15) between soil moisture treatments comparison showed higher %CP values of the
branches and seeds for the non-irrigated in the first harvest. The second harvest showed that
the irrigated had the higher values of % CP for branches while the non-irrigated had the
higher values for the rest of the other organs.
In 1993 between species comparison for the first harvest of the irrigated treatment revealed
that the leaves and stems of quinoa had more % CP while the seeds of amaranth had the
higher values. Comparison for the non-irrigated treatment of the first harvest showed that
amaranth had the higher value for the seeds only while quinoa had the higher values for the
rest of the other organs.
In the second harvest of the irrigated treatment in 1993, quinoa showed higher % CP values
than the branches, leaves and stems. In the second harvest of the non-irrigated treatment
quinoa had higher values in all but the seeds.
In (table 16) comparison between soil moisture treatments in the first harvest revealed that the
irrigated had the higher % CP in the branches. The same was observed in the second harvest.
In (table 17) comparison between soil moisture treatments in the first harvest showed that the
leaves and branches of the non-irrigated had a slightly higher % CP value. The second harvest
also showed slightly higher % CP alnes for branches, leaves and stems.
Ca
In 1992 comparing the species in the first harvest for the irrigated treatment revealed that
quinoa had the higher values for the leaves and stems while the non-irrigated showed higher
Ca values of amaranth for all the organs investigated except seeds.
Companing the irrigated treatments in the second harvest between species revealed that
amaranth had higher values in all but the seeds while in the non-irrigated it had higher values
in all the organs.
In table I4 comparison between moisture treatments in the first harvest showed slightly higher
values of Ca in the leaves of the non-irrigated treatment. Comparison in the second harvest
also showed a slightly higher value of Ca for the irrigated treatment.
In (table 15) between soil moisture comparison showed that the non-irrigated had higher
values in all but the branches during the first harvest, while the second harvest revealed higher
values for the branches and leaves of the non-irrigated but the seeds of the irrigated had the
higher value.
In 1993 between species comparison in the first harvest for the irrigated treatment showed
higher Ca values in all the organs of amaranth relative to quinoa. Comparison in the nonirrigated revealed the same result as in the irrigated.
During the same year, 1993, between species comparison in the irrigated of the second havest
revealed higher values in all but the seeds for amaranth, while the comparison between
species of the non-irrigated in the second harvest showed that amaranth had higher values of
Ca in all the organs.
In (table 16) between soil moisture treatments in the first harvest revealed that the nonirrigated had the higher values for branches and leaves while the second harvest showed
higher values of Ca for branches and stems of the irrigated but higher for the non-irrigated for
seeds and leaves.
In (table 17) between soil moisture treatments comparison in the first harvest showed the
irrigation leaves to be higher in Ca while second harvest showed the non-irrigated to be higher
for the leaves and the irrigated to be slightly higher in the branches.
P
In 1992 between species comparison in the first harvest for the irrigated did not reveal
substantial differences. The same was observed for the non-irrigated.
In 1992 between species Comparison in the second harvest did not reveal any differences in
the irrigated treatment while as slightly higher values were shown in the non-irrigated of
amaranth in the seeds.
In (table 14) between soil moisture comparison in the first harvest showed that the nonirrigated was slightly higher in P for the seeds, while the second harvest revealed no
substantial differences.
In (table 15) comparison between soil moisture treatments in the first harvest revealed a
slightly higher value for the non-irrigated in the seeds, while no substantial difference was
abserved in the second harvest.
In 1993 between species comparison in the first harvest of the irrigated revealed slight
differences in the leaves with amaranth having the higher value. The stems of quinoa were
however found to be slightly higher in the value. In the non-irrigated for the first harvest
amaranth had the higher values in the branches and the leaves, while quinoa stems had
slightly higher values.
In the second harvest of the irrigated treatment, quinoa had slightly higher P in the leaves
while the value of P was slightly higher in the stems of amaranth. In the non-irrigated
treatment of the second harvest quinoa had higher values in branches and leaves, while
amaranth had slightly higher value for the stems.
In (table 16) comparison between soil moistue treatment in the first harvest did not reveal any
substantial differences.The same was observed during the second harvest.
In (table 17) the first harvest showed the branches and leaves of the non-irrigated to be
slightly higher in P than the irrigated. During the second harvest no substantial differences
were observed.
K
In 1992 between species comparison for the first harvest of the irrigated treatment showed
substantial differences with quinoa having higher values for all the organs investigated. The
non-irrigated also showed differences with quinoa clearly having the higher value for all the
organs. In the second harvest of the irrigated treatment quinoa also had the higher value in K.
In the non-irrigated quinoa led in all but the stems.
In (table 14) between soil moisture comparison in the first harvest showed that the branches of
the irrigated had the higher value. In the second harvest the stems of the non-irrigated showed
higer values for K, while the branches of the non-irrigated had higher values for amaranth.
In (table 15) the non-irrigated had higher values in all but the leaves during the first harvest,
while the irrigated had the higher value in all the organs during the second harvest.
In 1993, between species comparison for the first harvest of the irrigated treatment showed
quinoa to have higher values in all the organs except the stems. The same was observed for
the non-irrigated of the first harvest and the second harvest of the irrigated. The second
harvest of the non-irrigated quinoa had higher values for the branches and stems, while
amaranth had higher K values for the leaves and seeds.
In (table 16) between soil moisture treatments comparison for the first harvest revealed that
the irrigated had higher values for all the organs. The second harvest showed that the irrigated
had higher values for the stems, while the non-irrigated had the higher one for the leaves and
branches.
In (table 17) between soil moisture comparison in the first harvest showed the non-irrigated to
be higher in values for the leaves and stems while the irrigated had the higher values for the
branches. In the second harvest the irrigated had higher K values for all the organs
investigated.
Mg
In 1992 comparison for the first harvest of the irrigated combination showed that amaranth
had slightly higher values for the leaves and stems, while quinoa had slightly higher ones for
the branches and seeds. In the non-irrigated treatment amaranth had slightly higher values for
the branches and leaves while quinoa was observed to have a slightly higher Mg for the seeds.
During the second harvest the leaves of amaranth were observed to have the higher value for
the irrigated while no substantial differences were found in the non-irrigated combination.
In (table 14) between soil moisture treatmentss comparison showed that the branches and
stems of the non-irrigated were higher in Mg while the stems of the irrigated had the higher
value for the first harvest. During the second harvest the irrigated had the higher value for the
leaves.
In (table 15) comparison between soil moisture in the first harvest revealed no substantial
differences. The same was also observed for the second harvest.
In 1993 comparison between species in the first harvest revealed that the stems of amaranth
had higher Mg values in both irrigated and non-irrigated. The second harvest revealed that the
stems of irrigated quinoa had the slightly higher value while the stems of the non-irrigated
amaranth again had higher value in that harvest. In (table 16) between soil moisture
treatments comparison revealed no substantial differences in the first harvest. In the second
harvest the leaves of the irrigated had the higher value while the non-irrigated had the higher
value for the seeds.
In (table 17) no substantial differences were found in the first harvest between soil moisture
treatments comparison. In the second harvest the seeds and branches of the irrigated treatment
had the higher value.
Zn
In 1992 between species comparison in the first harvest for the irrigated treatment revealed
that amaranth had the higher value for the stems and the leaves. It also had the higher values
for the branches, leaves and stems for the nor the non-irrigated treatment. The second harvest
revealed higher values for all the organs of amaranth for the irrigated treatment. The same
was observed for the non-irrigated treatment.
In (table 14) between soil moisture comparison for the first harvest revealed that the nonirrigated had the higher values in all organs but the stems, while the second harvest revealed
the irrigated to have the higher values in all the organs.
In (table 15) the irrigated had slightly higher values than the non-irrigated in the branches and
the leaves for the first harvest while it had the higher values for all the organs in the second
harvest.
In 1993 comparison between species in the first harvest for the irrigated treatment revealed
that amaranth had the higher values in all organs but the leaves. The same was observed for
the non-irrigated treatment. The second harvest of the irrigated revealed that amaranth had the
higher values in all the organs. In the non-irrigated treatment it had the higher values in all but
the leaves.
Comparison between soil moisture treatments, (table 16), revealed that the irrigated had the
higher values in all the organs for the first harvest, while the second harvest revealed that the
non-irrigated had the higher values in all but the seeds.
In figure 17, between soil moisture treatmentss comparison in the first harvest revealed that
the irrigated had the higher values in all the organs while the second harvest showed that the
irrigated had higher values in the case of branches but the non-irrigated had the higher value
for the leaves.
Cu
In 1992 comparison between species for the first harvest in the irrigated combination showed
that amaranth had the higher value for the branches while quinoa had slightly higher ones for
the leaves and the stems. The non-irrigated treatment revealed that quinoa had the higher
value in the organs.
The second harvest of the irrigated treatment showed that amaranth had the higher values for
the branches and the seeds while quinoa had the higher value for the leaves and the stems. In
the non-irrigated amaranth had the higher value only in the branches while quinoa had the
higher values for the rest of the other organs.
In (table 14) between soil moisture comparison in the first harvest revealed that the irrigated
had the higher values in all the organs, while the non-irrigated had the higher values in all
organs for the second harvest.
In (table 15) comparison between soil moisture treatmentss in the first harvest revealed that
the non-irrigated had higher values for all the organs, while it had higher values in the leaves
only for the second harvest.
In 1993 comparison between species for the first harvest of the irrigated revealed that
amaranth had higher values for all organs except the leaves while the non-irrigated showed
that quinoa had higher values than amaranth in all organs but the seeds.
The second harvest of the irrigated treatment revealed that amaranth had slightly higher
values for the branches while quinoa had the higher ones for the leaves, and the non-irrigated
on the other hand showed that quinoa had the higher value in all the organs, but the seeds.
Mn
Comparison between species in 1992 for the irrigated treatments of the first harvest showed
that quinoa had the higher value in all the organs except, in the stems, while the non-irrigated
revealed that amaranth had the higher value for the branches but quinoa again had the higher
values for the remaining organs. The irrigated treatment of the second harvest revealed that
amaranth had the higher value for the branches but quinoa had the higher ones for the other
organs. The same was observed for the irrigated treatment.
In (table 14) between soil moisture treatments comparison in the first harvest revealed that the
non-irrigated had the higher values in all organs but the stems, while the second harvest
showed that the non-irrigated had the higher values for the branches and leaves but the
irrigated treatment had a slightly higher one for the seeds.
(table 15) showed that between soil moisture treatmentss showed that the non-irrigated had
higher values in all but the seeds for the first harvest while the second harvest revealed that
the irrigated had the higher ones in all but the leaves.
In 1993 comparison between the species for the first harvest of the irrigated treatment
revealed that quinoa had higher values in the branches and the leaves while amaranth had
higher ones for the seeds and the stems. The non-irrigated revealed higher values for quinoa
for all the organs. The second harvest revealed that quinoa had higher values for all but the
stems of the irrigated while it had the higher for all of the non-irrigated treatments.
Comparison between soil moisture treatmentss in the first harvest, (table 16), revealed that the
irrigated treatment had the higher values for all the organs, while the non-irrigated had higher
value for the leaves in the second harvest but the irrigated had higher ones for the branches
and the seeds.
In (table 17) between soil moisture treatmentss comparison showed that in the first harvest the
non-irrigated treatment had the higher values in all the organs. The same was also observed
for the second harvest.
Fe
In 1992 between species comparison for the first harvest of the irrigated treatment showed
amaranth to be higher in values for all the organs except the seeds while the non-irrigated
showed that amaranth had the higher value for the branches and the leaves but quinoa had the
higher ones for the seeds and stems.
In the second harvest of the irrigated, amaranth had the higher values for the leaves and
branches while quinoa had the higher values for the seeds. In the non-irrigated for the second
harvest amaranth had the higher values of branches and the leaves while quinoa had higher
ones for the stems.
In (table 14) between soil moisture comparison showed that the non-irrigated had higher
values in the branches and leaves while the irrigated had the higher value for the stems of the
first harvest. The second harvest showed that the non-irrigated had the higher value for all the
organs except the branches.
In (table 15) comparison between soil moisture combination for the first harvest showed that
the irrigated had the higher values for the branches and leaves while the non-irrigated had the
higher ones for the seeds and stems. The second harvest showed that the irrigated had the
higher values for all the organs but leaves.
In 1993 between species comparison revealed that in the first harvest of the irrigated
treatment amaranth had the higher values for the seeds and stems, while quinoa had the higher
values for the branches and the leaves. In the non-irrigated amaranth had the higher values in
all the organs.
In the second harvest of the irrigated treatment amaranth had the higher values for all the
organs except the branches, but the non-irrigated showed that amaranth had higher values for
all the organs.
In (table 16) between soil moisture comparison showed that the non-irrigated had higher
values for the seeds and stems while the irrigated had higher ones for the leaves and branches.
The second harvest revealed that the non-irrigated had higher values for the branches and
leaves while the non-irrigated had higher values for the stems.
In (table 17) the first harvest showed higher irrigated values for all the organs while the
second showed higher values for the irrigated treatment for the branches and seeds but the
non-irrigated had the higher value for the leaves..
Between cropping seasons, differences were also observed. They were clearly manifested in
Phosphorous with the 1993 cropping season having the higher values. It was the wetter of the
two seasons.
4 DISCUSSION
The seed yields obtained in the field experiments were in the range of 242.5-540.0 g m-2 and
may be classified as rather high ones (Roszewski 1995). Comparing seed yields it can be seen
that: a) both irrigated and non-irrigated quinoa and amaranth did not respond substantially
during 1992; b) non-irrigated quinoa did not show differences in yield between 1992 and
1993, c) in 1993 irrigated quinoa yielded twice as much as in 1992, and d) in 1993 both
amaranth yielded less than in 1992. Therefore, causes of such differences in yielding could
not be only attributed to the effect of experimentally simulated drought but involved its
interactions with the time course of the weather during the whole cropping seasons as well
(1992 dry and 1993 rainy ones).
Seed yields of quinoa might have been affected by the unfavorable daily average temperatures
of 25oC, very often exceeding 35oC, reached in the very hot summer of 1992, because optimal
temperature for the crop is about 15-20oC as is prevailent in Altiplano plateau in the Andes in
the vicinity of the Titicaca Lake, 3700 m over sea level with maximum temperature of 23oC
(Vacher, personal communication). It is why, even irrigation did not overcome the negative
effect exerted by elevated temperatures on this temperate crop yielding. Amaranth is a warm
climate plant (Kigel 1994) and it is cultivated in very hot regions such as Sierra Leone (Sesay
1991), so in 1992 in Poland (hot season) it yielded enormously well.
The final seed yields of both studied crops in 1992 and 1993 were results of their harvest
index (HI) combined with total biomass production. Especially interesting was the HI for the
non-irrigated amaranth in 1992, 0.36, which was extremely high compared with the irrigated
one, 0.19. The non-irrigated HI for 1992 was equally high relative to the non-irrigated and
irrigated ones in 1993 (0.19 and 0.16, respectively). Different HIs of amaranth in both studied
combinations in 1992, did not reflect same in seed yields although dry matter of the whole in
the high soil moisture plants was twice that in the low soil water content. Also HI of quinoa
was higher for non-irrigated than irrigated plants in 1992, 0.20 versus 0.16. However quinoa
yields were similar then. In 1993 HI for quinoa was lower for non-irrigated (0.13) than for
irrigated ones (0.16). Thus, under unfavorable climatic conditions of 1992 total dry matter of
both species was reduced but final seed yield was not changed. Higher HIs got in 1992 for
non-irrigated studied crops could be the outcome of not only water shortage, but may also be
due to higher temperature, on average an increase from 20oC by 5oC, after July, 15th. It might
also be due to the negative effects of nitrogen fertilization at elongation stage when there was
not enough soil water for its uptake and use.
In 1993 HIs of both crops, independent of irrigation, were in the range 0.13-0.19 and observed
differences in final seed yields were caused mainly by differences in their biomass
production. Quinoa, being a C3 plant with relatively lesser WUE, benefited much more under
the rainy season of 1993 and irrigation than amaranth (C4 plant) (Edwards and Walker 1983).
Despite higher soil moisture in 1993 than in 1992, seed yields of amaranth were lower in 1993
than in 1992. This could have been the result of poor conditions of low temperature for seed
formation at the end of growth. Therefore, the HI results of amaranth for both combinations
and cropping seasons showed that although increases in the vegetative or biological yield
were realized due to irrigation, the economic yield if in the form of the seeds, did not respond
to watering at all. The same result was obtained in the 1992 pot experiment. Plant adaptation
to water shortage depends not only on photosynthetic pathway, but also osmotic adjustment,
root development, etc. (Kigel 1994) The benefits of irrigation may be realized if plantations
are grown for forage in both species.
Higher HIs of the non-irrigated than the irrigated plants seem to be of emence agronomic
importance, both in terms of economic yield as well as during harvest. Size of A. cruentus
shoots led to unnecessary combined harvesting problems using a cereal combine harvester.
Massive size and stiffness of the shoots of amaranth interferred with the normal movement of
the rotor (Chlebowski 1994). The moisture content in amaranth is usually high at harvest,
unlike in true cereals. The high moisture dampened the seeds markedly causing post-harvest
problems. Hence, the lesser the size of the stem due to non-irrigation, the better.
The Yield of
both pseudocereals,
as in other plant species, was a product of many
physiological processes such as photosynthesis, respiration and assimilate distribution, which
are in turn modified by such factors as soil water content, irradiance, soil and air
temperatures, photoperiodicity etc. (Maleszewski et al. 1993, Loboda 1994). On the basis of
the performed measurements the correlation coefficients between various gas exchange
parameters were calculated for both plot and pot experiments. Noteworthy is that the
correlation between photosynthesis and stomatal conductance was found, although the extent
of the significance of the correlation was somehow variable. In quinoa (C 3 plant), especially
under the high soil moisture, these two prameters were found to be correlated (r= 0.89-0.90),
while for amaranth (C4 plant) no significant correlation was found between the same
attributes for the high soil moisture level. Photosynthesis and intercellullar CO2 (Cint) were
usually not correlated. As significant differences existed between species in the intercellullar
concentration of CO2 with quinoa comparing favourably to amaranth, it is rather plausible to
state that this is related to the different carboxylation pathways (Ehleringer and Monson
1993).
The specific significant differences between species and soil moisture treatments in the plot
and in the pot experiments of 1992 and 1993 in stomatal conductance may be connected with
the fact that amaranth has an effective mechanism of trapping CO2 from the various metabolic
processes reuse it, preventing it from escaping out through the stomata (Edwards and Walker
1983, Sestak 1985). In this way, the C4 plants are able to open their stomata economically, in
so far as minimizing transpiration, unlike C3 plants (Bethenod et al. 1996).
Some studies are of the conclusion that partial closure may be generally beneficial for plants
(Waggoner and Zelitch 1965; Shimshi 1963, Raschke 1976), however, photosynthetic rate is
proportional to stomatal conductance (Farquhar and Sharkey 1982, Mansfield et al. 1990).
Indeed, the 1992 plot plants of quinoa showed that the plants with imposed water shortage
had lower stomatal conductance than the unstressed ones. More drought resistance varieties of
herbaceous and even tree mesophytes show a greater degree of stomatal closure than the less
resistant varieties of oats (Stocker 1956), peanuts (Gautreau 1970), sorghum (Henzell et al.
1975, 1976) and red maple (Townsend and Roberts 1973).
The obtained higher WUE for amaranth (C4) than for quinoa (C3) was in agreement with data
of Ehleringer and Monson (1993). In both 1992 and 1993, higher WUE observed for nonirrigated plants of both studied species was mainly a result of their lower photosynthesis and
transpiration.
Transpiration and intercellular CO2 were found to have no correlation in all experiments,
while transpiration and stomatal conductance were found to do so only in 1993 (r=0.89-0.94).
There is increasing evidence that plants detect conditions in the soil directly and respond
accordingly to deteriorating conditions well before their roots lose the ability to extract water
fast enough for their needs (Blackman and Davies 1985, Pasioura 1988a, Saab and Sharp
1989, Blum et al. 1991, Davies and Zhang 1991, Gowing et al. 1991). The roots send
inhibitory signals to the leaves that may slow leaf expansion and close stomata well before
any fall in water status is evident in the shoot. When they do so they are in effect displaying a
feed forward response. The hormones such as abscisic acid (ABA) implicated in the
feedfoward response are carried in the transpiration pool. Tardieu et al. (1992 b) suggested a
definite correlation between xylem ABA and stomatal conductance. Tardieu et al. (1992 a)
and Wartinger et al. (1990) reported that increases of xylem ABA of less than 200 mol m-3
for plants in the field may lead to 90% reduction in stomatal conductance. Furthermore even
if we consider the findings of Tardieu et al. (1992 b) leaf water potential (Vacher 1996) is as
important as ABA in stomatal conductance and in this way in transpiration. ABA is
synthesized by dehydrating roots (Cornish and Zeevart 1985; Watton et al. 1976) in non-
growing tissues as well as in apices, and in the cortex as in the stele (Harting and Davies
1991).
The assimilated during photosynthesis CO2 undergoes distribution within plants so to evaluate
seed yielding potential and study transport of carbon to forming seeds (Nalborczyk et al.
1981) radiolabelling was used at flowering stage.
The trend of significant specific differences, indeed in some organs even highly significant, in
both the low and high soil moisture combinations was found to be the same.Higher values
observed in the top, middle and bottom leaves of both amaranth treatments and higher values
in the flowers and the branches of quinoa in the radioactivity may be due to quinoa flowers
been stronger acceptors hence they had priority in the allocation of photoassimilates (Huber
1983).
Quinoa compared favorably to amaranth in the radioactivity of the branches as amaranth does
not put a premium in the development of branches. The contribution of the branches in the
total plant weight is small in amaranth (Chwedorzewska and Nalborczyk 1994) compared
with quinoa. During the first harvest of amaranth low soil moisture combination revealed the
readily-noticeable early development of branches. Indeed, drought led to early appearance of
branches probably as a means of preserving resources (Chwedorzewska and Nalborczyk
1994).
The finding the low soil moisture combination displayed the higher radioactivity with respect
to the bottom leaves in amaranth during the first harvest may be connected with the allocation
of photoassimilates from the branches, to which they are closest. Indeed, Huber (1983) stated
that sinks seem to be supplied largely from source leaves near to them. The low soil moisture
compared favourably to the high soil moisture combination in the petioles what may be due to
the fact that turgor in the phloem of the petioles of the high soil moisture combination
enhanced speedy flux translocation (Farrar and Minchin 1991).
The low soil moisture compared favourably to the high soil moisture combination in the top
leaves, which were not mature enough during the first harvest to optimize photosynthesis it
may be due to import of assimilates to enhance growth and metabolism (Farrar and Minchin
1991). It is likely that the top leaves, of the low soil moisture combination were initially sinks.
During the second harvest, amaranth again displayed higher values in most organs except the
branches. The changes of the distribution pattern of the two species during this harvest were
characteristically different. In amaranth the flowers, stems and the petioles gained at the
expense of the branches, top, middle and bottom leaves and specific distribution pattern was
conserved in both the high and low soil moisture combinations, by giving priority to the
flowers and stem (Wallop 1995). In quinoa conservation of a specific distribution pattern was
not observed. The flowers gained considering their strategic position to the top, bottom and
middle leaves. In the low soil moisture however, the bottom leaves were noted to have gained.
The distribution pattern may have been influenced by sink strength rather than distance from
source (Geiger et al 1985; Huber 1983; Starck and Ubysz 1974).
In accordance with the time course of the growth indices (Cartujano et al. 1985,
Chwedorzewska 1994) during both cropping seasons, for the two species in both
combinations, three developmental phases were identified. Phase “A” characterized early
development, phase “B” concerned secondary development, in preparation for the third and
final phase “C” describing the generative phase. Obviously the beginning or end of those
phases sometimes differ due to either specific or climatic reasons. The three phases of growth
and development were more accentuated in 1993 than in 1992 in both combinations and
species.
The increase in ASI and LAI in phase “A” of both combinations of A. cruentus in 1992
signified a high percentage contribution of the assimilatory surface during the first part of the
phase. Notwithstanding the huge contribution of the assimilatory surface area at the begining
of the phase, RGR and CGR did not respond favourably to irrigation. The reason may be that
most of the leaves present were too young and could not yet reach high net photosynthesis
(Sestak 1985). This is substantiated by the reduced ULR. The differences in CGR between
combinations in the beginning might have been reflected in the SLA. The differences in
thickness may be due to that the irrigated plants had more biomass which enabled them, in
turn, produce more, leading to increased growth.
The dynamics of biomass accumulation as well the values of LAI and LAD during the phase
“B” markedly showed that the canopy was closing up. The assimilatory surface could not
fetch optimum increase in biomass. The moisture condition during this phase was sub-optimal
as indicated by much lower than 1 hydrothermal index. This may have caused the reduced
efficiency of the assimilatory apparatus (Cartujano et al.1985, 1987).
The reduction in the size of the assimilatory apparatus, in both combinations during phase
“C”was substantiated by the percentage contribution. The initial rise of SLA may be
associated with the increased contribution of young thinner leaves to LWR and LAR, which
continued to decrease. The late development of the assimilatory apparatus in the non-irrigated
combination was reflected by the rise in ULR, except for the brief fall during the period
between 79 and 91 DAE.
In phase “A”, in 1993 A. cruentus developed a huge assimilatory apparatus. but the
difference between combinations was almost unnoticeable.The initial robustness in growth
and development of the assimilatory apparatus was reflected in its elevated ULR, CGR and
RGR. Both CGR and ULR were noted to end up with a significant rise at the end of the phase.
Same RGR ended rising in both combinations by then. The SLA fell steeply during the phase,
indicating the rate at which the thickening was taking place. Later, as is mostly the case
(Evans 1972, Hunt 1982, Lambers and Poorter 1992), it did not change very much throughout
the cropping season.
The second phase (“B”) coincided with the production of the branches. The phase revealed a
reduction in the percentage contribution of the assimilatory apparatus. The RGR ended
markedly lower than it started at the end of this phase, although ULR increased. The decrease
of the photosynthesizing to the non-photosynthesizing parts of the plant through the
developmental phases in terms of LWR and LAR kept falling leads to a reduction in RGR
(Cartujano et al.1985, 1987).
The CGR also revealed little response to ontogeny by the end of the phase. This may be due
to the fact that ULRc and LAI were also less responsive. Both indices are related to CGR by
way of the following relationship: CGR = ULRc x LAI (Watson 1947, Nichiporovich 1967,
1968, Ustenko and Yagnova 1967, Wassink 1968, Pietkiewicz 1985). The ULRc did not differ
from the indices of the individual plants. Some important factors of net photosynthetic
production are the size of the assimilatory organ and leaf arrangement. These factors may lead
to mutual shading and thus reduce ULRc as against that of single leaf (Stoy 1965).The lack of
marked differences in the progress of both ULRc during both cropping seasons, 1992 and
1993, might be due to the fact that the size of the assimilatory apparatus caused the closure of
the canopies. This may have been more beneficial than the negative effects of mutual shading
especially in the area of reducing the temperature of the soil below the canopy which, in turn,
indirectly promotes net photosynthesis (Watson 1952).
The third phase (“C”) revealed further reduction in the percentage contribution of the
assimilatory apparatus and LWR and LAR reflected the reduced percentage contribution of
leafage.The LAI was the only one describing green parts of plants in the non-irrigated
combination which did not depict the reduced assimilatory surface during the phase. The
CGR which was equally less responsive to ontogeny than RGR and ULR reached its peak in
both combinations during this phase and it looked like CGR took more after LAI than ULR in
the equation expressing CGR.
Indeed, Watson (1947, 1952, 1958) stated that in most stands a knowledge of the changes in
LAI is the key to understanding the changes in other growth characteristics especially ULR,
which in this case displayed inverse relationship as suggested by Stoy (1965). Duration of
time over which the plant maintains its active assimilatory apparatus in terms of LAD as
integral of LAI is very important as it is sometimes used to estimate ULRc by dividing the
maximum attained weight by the over time integral of the crop assimilatory surface A c
(Nichiporovich et al. 1961; Kvet 1962; Stoy 1965) or since it used to be highly correlated with
the yield more than any other characteristic (Birke 1965).
As in 1992 in C. quinoa the dynamics of biomass accumulation in phase “A” rose steeply it
probably intuitively reflected good progress in early crop establishment. In phase “B” it was
revealed a reduction in the percentage contribution of the leaves in both combinations while
the branches increased their contribution in the irrigated but somewhat reduced their
contribution in the non-irrigated treatment. The dynamics of biomass accumulation in the
phase means the plants were using their huge assimilatory surface from the first phase to add
to their biomass. The irrigated combination had lesser gradient, with smaller dynamism and
the SLA revealed differences between the combinations. The LAI increased in both
combinations, leading to closing up of canopies
The third phase (“C”) revealed a clear reduction in the percentage contribution of the
assimilatory apparatus. The dynamics of biomass accumulation increased in the irrigated
combination and fell in the non-irrigated, at the beginning of the phase. The CGR also
showed differences though in both combinations a fall was recorded. The fall both of CGR
and RGR may be due to the increase in the contribution of the non-assimilatory organs, such
as the inflorescence to the plants DM.
The 1993 C. quinoa phases were also similar to the three earlier-mentioned ones. Phase “A
“also revealed significant gains in assimilatory apparatus. The ULR values in both the canopy
and the single plant slightly differed between combinations. The non-irrigated plants reached
its highest value at the end of this phase while the irrigated ones reached
by then its least
value. The irrigated had already started to show signs of the inverse relationship between
ULR and LAI even at the end of the preliminary phase. In phase “B”, the assimilatory
apparatus increased considerably, especially in the irrigated combination where the LWR was
rising from a local minimum. The dynamics of biomass accumulation in both combinations
showed considerable gain. In phase “C” the gain in the assimilatory surface was clearly
reflected by the dynamics of biomass accumulation curve.
If one reconsiders the growth of amaranth and quinoa in view of dry matter contribution of
principal organs then it noteworthy that during the hot summer 1992 there were lesser leaves
especially in the non-irrigated combinations than in 1993, and less petiols especially for
nonirrigated amaranth in 1992. Also under low soil water content and high temperature
(1992) there were less branches than in 1993. The percentage of the main inflorescences
under all treatment of amaranth was much higher than in 1993, while quinoa developped that
year earlier auxillary ones.
Higher nitrogen (crude protein) content in the leaves of quinoa than in amaranth reflects
differences in their photosynthetic pathway, mainly its allocation to rubisco which is the
principal N-compound in the leaves and there is more of this enzyme in C4 than C3 plant
(Sage and Pearcy 1987, Kigel 1994). Amount of nitrogen could influence stomatal
conductance of irrigated and non-irrigated plants because the decreasing nitrogen per leaf area
caused lower stomatal conductance (Hunt et al. 1985).
Taking into account the same yields in both amaranth combination in 1992 but much lower
ASI and much higher HI in non-irrigated combination than in irrigated one, it is tempted to
speculate that in the former ones a significant amount of organic compounds, including Ncontaining compounds, needed for seed formation was stored in vegetative parts of the plants
and remobilized later on.
The absence of any measurable defficiency syndrome clearly shows the efficiency of both
alternative crops in the management of the nutrients. Even the low moisture treatment which
cause reduced levels of the micronutrient did not show any syndromes. Uptake of the nutrient
by both crops was similar. It was noted that results reached in this experiment were largely
comparable to those of Bressani (1988), Saunders and Becker (1983) and De Bruin (1964).
CONCLUSIONS
1. Water shortage influences both biomass production and harvest index (HI) by decreasing
and increasing respectively for A. cruentus (C4 plant) and C. quinoa (C3 plant).The
situation was accentuate by the hotter season of 1992.
2. Under hot and dry season conditions, amaranth yields were much higher than quinoa
independent of ample soil moisture conditions or not, while under rainy and cooler season
seed yield of the latter species benefits much more.
3. WUE of amaranth is higher than that of quinoa and under water shortage changes
proportionally for both species due to substantial reduction of photosynthesis and this drop
is higher in amaranth than quinoa.
4. Reduced soil moisture results in higher allocation of photosynthate towards inflorescences
and seeds of amaranth than in quinoa.
5. Drought negatively affects RGR mainly by lowering ULR whereas the LWR is not
changed but SLA increases.
6. Under low soil moisture CGR of both crops decreases due to simultaneous diminishing of
LAI and ULRc but the pattern of the latter is inherent in CGR changes.
7. Under weather conditions similar to those in 1992 and 1993 water shortage does not
severely affect mineral relations of A. cruentus and C. quinoa.
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TABLE 13: FERTILIZER APPLICATION IN POTTED EXPTS.
TIME OF
APPLN.
MACROELEMENTS
BEFORE
SOWING
Fertilizer
MICROELEMENTS
Amt./pot
(g)
Amt. of
H2O/pot
Fertilizer
Amt./pot
(mg)
(ml) ***
KNO3
2.16
20
H3BO3
5
NH4NO3
2.00
20
MnSO4
5
K2SO4
0.74
20
ZnSO4
0.2
MgSO4.7H2O
0.65
20
CuSO4
0.2
KH2PO4
0.575
10
NH4 -
0.5
Molybdate
Ca(H2PO4)2.H2O
0.89
Dry
Fe-citrate
0.1
(1%)
EARLY
FLOWER
BUD
NH4NO3
4.57
20
Fe-citrate
0.1
(1%) only
C. quinoa
STAGE
FULL
FLOWERIG
NH4NO3 (only MT-3)
4.57
20
none
STAGE
*** Amount of water per pot needed to dissolve or disperse fertilizer.
none
APPENDIX 1
Below are two pictures from the 1992 potted experiment. Top picture shows amaranth
and quinoa at the intensive growth stage while the bottom picture shows a closer view of
quinoa at this same stage.
APPENDIX 2
Below are pictures from the 1992 potted experiment. The top picture shows amaranth and
quinoa. Early maturing quinoa was already at the stage of final harvest while amaranth
was not. The bottom picture shows amaranth at the stage of final harvest.
APPENDIX 3
Immidiately below our background shows irrigated amaranth (left) and quinoa (right) in
the early flowering stage while the bottom picture shows irrigated amaranth and quinoa
(far right) in the mid flowering stage from the 1992 plotted experiment.
APPENDIX 4
Top picture shows irrigated amaranth at full flowering while bottom largely shows
irrigated quinoa (1992).
APPENDIX 5
Top picture shows non-irrigated amaranth and quinoa at mid flowering, while bottom
shows the same species at full flowering stage (1992).
APPENDIX 6
Top picture shows irrigated amaranth and quinoa at the flower bud stage while bottom
picture shows non-irrigated amaranth (foreground) and quinoa (background).
APPENDIX 7
Top picture measurement with the Li-6200 gaseous exchange equipement while bottom
shows amaranth and quinoa before final harvest (1993 expt.).