Download et al - Shodhganga

CHAPTER-VII
DISCUSSION
Since the oil crises of the 1970s and recognition of the limitations of
world oil resources, vegetable oils have received special attention. However,
recently plantation of Jatropha curcas as an energy plant was realized and tests
of its seed oil indicate that, it is a potential substitute for diesel fuel. Its wide
ranging utility have made it quite popular. Considering this, it is necessary to
increase the seed production of this species by planting superior genotypes to
get the maximum oil production.
The present investigation was undertaken to (a) evaluate the provenance
variation in seed, germination and seedling growth in nursery and field
conditions, (b) investigate the effect of various environmental factors on
germination of seeds, (c) analyze various nursery techniques for the production
of quality seedlings and (d) standardize the proper management practices for
the establishment of J. curcas plantation.
Provenance Variation
The purpose for provenances testing is to measure the pattern of genetic
variation and to aid in selection of well adapted and highly productive
provenances. Therefore, the screening of provenances is essential to determine
the most promising provenances for specific geographic area. Geographic
collection and planting zones can be delineated if provenance testing is
conducted during the early stages of a tree breeding programme. J. curcas is
semi-wildly distributed in different parts of India. Thus, it would be expected to
have considerable genetic variation. Cause of such variability might be
generally attributed either to genetic character of source population/plant
(Bewley and Black 1994) or impact of mother plant environment (Gutterman
1992). To screen the naturally available varieties and to select the best
Discussion
provenance, seeds for the present study were collected from 14 provenances
covering wide range of species distribution and these provenances were tested
at Kumarganj, Faizabad in eastern U. P.
The occurrence of J. curcas over a wide range of habitats with a diverse
edapho-climatic conditions expected to be reflected in the genetic constitution
of its diverse populations. In the present study, a considerable variation in J.
curcas seed length, width, thickness and weight was observed among various
provenances. Seed length was highest for Indore provenance, while seed width,
thickness and weight were found to be highest for Kottayam provenance. The
variation in seed characteristics of J. curcas has also been reported by
Gurunathan (2006). It is possible that the variation in morphological characters
between provenances is due to resource availability at the time of seed
development. This variation could be due to different environments at the
geographic origins of each seed.
Among the various seed traits, the higher variation was exhibited by seed
moisture content and seed weight. Tiwari (1992) have also reported large
amount of variation in seed weight for different provenances of Azadiractha
indica. Seed weight is one of the useful criteria for early selection of superior
provenances (Khalil 1986). Seeds with high moisture content at the time of
dispersal have been reported to germinate faster than the ones with low
moisture content. High moisture content in Kottayam seeds could be a reason
for high germination (Table-3.2). According to Ghosh (2006), seed weight is
also related to oil content. However, in the present study the correlation
coefficient between seed moisture content with germination per cent and seed
weight with oil content was not significant (Table-3.6). According to Gera et
al. (2004), geographical factors (latitude, longitude, altitude, rainfall and
temperature) play a major role in the seed germination, but in the present study,
seed germination was not significantly influenced with any geographical factor.
However, latitude showed a significant negative correlation with seed weight,
93
Discussion
width and moisture content (Fig.7.1). Thus, Kottayam, located at lower latitude
showed highest seed weight.
Age, vigour, canopy exposure and genotype of the plant also influence
the quality of seeds (Mathur et al. 1984). However, in this study the seed from
different provenances were collected from healthy trees of approximately the
same age. Thus, the variation observed in seed traits may be due to the different
genetic architectures developed as a result of adaptation to various
environmental conditions existing throughout their distributional range. Similar
observations have also been made by Salazar and Quesada (1987) for Guazuma
ulmifolia.
A significant variation was observed in seed germination, germination
value, speed of germination, plant survival and other germination parameters
amongst various provenances of J. curcas. Kumar et al. (2003) and Anon
(2005), have also observed a considerable variation in germination of J. curcas
seeds collected from different provenances. The variations in germination traits
among provenances are also in conformity with those found in Q.
leucotrichophora (Nautiyal et al. 2000), Pinus roxburghii (Todaria et al. 2003),
D. sissoo (Devagiri et al. 2004), Prunus armeniaca (Bhan et al. 2006), Cordia
africana (Abraham et al. 2006) and A. indica (Mahto et al. 2006).
In the present study, germination showed a significant positive
correlation with the seed weight (r = 0.802). The provenances which had higher
values for seed weight also showed higher germination (Fig. 7.2). Nizam and
Hossain (1999) have reported that in Albizia samen heavier seeds performed
better than the lighter seeds. Arunachalam et al. (2003) have observed that in
Mesua ferrea heavier seeds showed early and rapid germination. This may be
attributed to the larger food reserves with greater nutrient pool present in the
endosperm of the heavier seeds. Variation in germination value among various
provenances is in conformity with those found in Fir and spruce (Singh and
Singh 1981), Acacia spp (Mathur et al. 1984) and Albizia falcataria (Bahuguna
94
Discussion
et al. 1989). A significant positive relation between seed weight and
germination value confirms the views of Czabator (1962) and Dunlap and
Barnett (1983), that germination value is an index combining speed and
completeness of germination, which in itself is a function of seed weight.
Speed of germination also showed a significant positive relationship with the
total germination percentage (r = 0.922; P<0.01) and germination value (r =
0.986; P<0.01) which are also in conformity of above views.
Various growth parameters i.e., seedling height, collar diameter, number
of leaves, etc. at the age of eight months in the nursery differed significantly
among various provenances. Provenances such as Kottayam, Ambikapur,
Raipur, Indore, Jhansi and Coimbatore falling under extreme, tropical climate
with hot summer and well distributed rainfall area, were the better growing
provenances under the environmental conditions of Kumarganj, Faizabad.
Among these provenances Kottayam seed lot indicated the first rank. The
Bhubaneswar, Jodhpur and Nagpur provenances indicated lower growth under
this environmental condition. The variation in seedlings traits could be due the
fact that J. curcas is able to sustain a wide range of stress, i.e., moisture,
temperature, altitude and soil type at different ecosites. Such variation in
relation to habitat has also been reported in A. lebbeck (Kumar and Toky 1996),
Acacia mangium (Salazar 1989). Rehfeldt and Wycoff (1981) reported that the
seedlings raised from different provenances often display different pattern of
root and shoot growth. However, it is not always easy to show that such
differences are adaptive, presumably in response to the environment of the
parent seed origin. The present experiment was conducted under a controlled
nursery condition where the environmental deviations are negligible, therefore,
the observed variation in various growth characters among provenances may be
genetic in nature. However, the inconsistent behaviour of the seed sources in
nursery and plantation indicates that under the ideal conditions in nursery
seedlings of various provenances could not express themselves completely.
95
Discussion
Sniezko and Stewart (1989) have also reported that the variation between
provenances and within provenances in nursery traits is essentially genetic in
nature. Provenance variations in the field conditions were also observed for
different growth parameters. In the present study Kottayam provenance
emerged as the best growing provenance in the nursery as well as in field
condition.
Seedling growth parameters are interdependent and are governed by
seed traits, genetic makeup and environmental influences (Dunlap and Barnett
1983; Pathak et al. 1984). In this study seed length and seed thickness showed
a positive relationship with seedling height, collar diameter, number of leaves,
seedling dry weights of leaf, shoot, root and total in the nursery and with
seedling height and collar diameter in field condition. According to Chauhan
and Raina (1980), growth parameters have strong positive relationship with
seed size and weight and these regulate germination and subsequent plant
growth. Hence, the variation in seed size might have resulted in significant
differences among provenances at nursery as well as in field condition.
Various growth parameters of seedlings in nursery as well as in field
were found to be correlated positively with each other (Table-3.6 and Fig.7.2).
This suggested the need to adopt the multi-trait selection for a productive
provenances, as was also reported by Vakshasya et al. (1992) for D. sissoo.
Seedling dry weight parameters, viz., leaf, root, shoot and total dry weight
varied significantly among provenances. Since these parameters were found
correlated with growth parameters like plant height, collar diameter and
number of leaves, variation in the later is the possible reason for variation in
dry weight parameters. Furthermore, the root and shoot parameters, a function
of seed traits (Pathak et al. 1984), correlate with plant height and diameter,
hence, the variation observed in seed traits resulted in root and shoot variation
among provenances. Differences in the seedlings dry weight parameters,
therefore, can be attributed to the differences observed in both seed and growth
96
Discussion
traits. These findings are in consistence with those reported in Acacia spp
(Mathur et al. 1984).
In the present study, growth parameters (seedling height, number of
leaves, root and total seedling dry weight) and plant per cent exhibited a
significant negative correlation with Latitude (Fig. 7.1). This indicates a poor
growth of provenances from higher latitude as compared to the provenances
from lower latitudes. On the other hand, longitude of the provenances did not
show significant correlation with growth parameters.
In terms of different growth traits, the rank of top 5 provenances changed
at different growth stages in the nursery (Table-7.1). In the field condition,
Table-7.1: Changes in rank among the top 5 provenances in nursery at 2 to
8 months stage and in field after 3, 6, 9, 12 month plantation for
height and collar diameter in J. curcas
Rank
I
II
III
IV
V
I
II
III
IV
V
In Nursery Condition
Seedling height
Collar diameter
2
4
6
8
2
4
6
8
month month month month month month month month
3
2
3
3
2
13
13
13
8
8
13
13
3
3
2
3
2
3
2
2
13
2
3
2
13
6
10
8
10
10
8
8
10
13
8
10
8
6
6
10
In Field Condition
Seedling height
Collar diameter
3
6
9
12
3
6
9
12
month month month month month month month month
13
3
3
3
13
3
3
3
3
13
13
13
3
13
8
8
2
2
2
2
8
8
2
2
10
10
10
10
2
2
13
13
8
8
8
8
6
6
6
6
*1 = Ahmedabad, 2 = Ambikapur, 3 = Kottayam, 4 = Bhubaneswar, 5 = Hyderabad, 6 =
Indore,
7 = Jabalpur, 8 = Jhansi, 9= Jodhpur, 10 = Coimbatore, 11 = Mandsaur, 12 =
Nagpur, 13 = Raipur, 14 = Ratlam
on the other hand, rank of top 5 provenances in term of plant height was similar
after six months of plantation, while in terms of collar diameter it was constant
after nine months of plantation. This indicates that diameter is a relatively poor
97
Discussion
parameter to detect genetic variation at the early stage, and a longer growing
time is needed for a better expression of the genetic potential for this trait. This
leads the conclusion that provenance selection for these characters is probably
not very efficient in the nursery and collar diameter is considered to be more
sensitive to environmental conditions than height (Costa and Durel 1996).
Species with wide range of variability indicates enormous scope for
improvement in desired traits. This magnitude of improvement in germination
behaviour and growth traits depends upon the amount of genetic variability,
heritability and due to involvement in which trees are growing. The range
displayed high variability among the provenances for various seed and
germination traits. A little deviation between PCV and GCV for all the
germination traits indicates that the variation for these traits is mostly due to
genetic factors (Table-3.5).
Heritability in broad sense may give useful indication about relative
value of the selection of the material at hand. In present investigation, estimates
were found greater for germination energy, moisture content, germination per
cent, GV and SG. The genetic gain expressed as percent of mean was found to
be higher for GV, GE and moisture content. Thus, germination energy,
germination value and seed moisture content showing high genetic gain also
showed high heritability. The presence of high heritability values coupled with
high genetic gain for these traits suggests involvement of additive gene action.
This indicates that selection will tend to increase the frequency of allelles
producing the desired genotypes, as these traits are less influenced by
environment and they may maintain their superiority in subsequent generations.
Among the growth traits of the seedlings in nursery, height, collar
diameter, number of leaves and dry weights of leaf, shoot and total seedling
also indicated only a little deviation between PCV and GCV. The low
differences between PCV and GCV indicate the lesser influence of
environment and reflect on the reliability of selection based on phenotypic
98
Discussion
performance (Chopra and Hooda 2001). These traits further indicated higher
heritability also. In the field conditions the difference between PCV and GCV
was low for total height, collar diameter, canopy spread and number of
branches per plant. Plant height and number of branches, however, indicated
maximum heritability alongwith higher genetic gain. The high estimates of
heritability help the breeder in the selection programme.
The variability among different genotypes of a species is known as
genetic diversity or divergence (Singh 1993). It arises either due to
geographical separation or due to barriers to crossability. In this study all the
provenances were studied for genetic divergence involving various seed,
germination and growth traits using non-hierarchical cluster analysis (Baele
1969; Spark 1973). The provenances grouped together are less divergent than
the ones grouped in different clusters. The clusters separated by greatest
statistical distance show maximum divergence. Based on this method, 14
provenances of J. curcas were grouped into 4 different clusters. Cluster IV
included promising provenances viz., Ambikapur, Kottayam and Raipur
performed best, while in general, poor performing provenances occurred in
cluster III accommodating Bhubaneswar, Jodhpur and Nagpur provenances.
The minimum distance between cluster II and IV revealed that the provenances
belonging to these clusters were genetically closer. Among different clusters,
the IV showed high mean performance for all the studied characters.
In general, the clustering pattern in present study indicated that diversity
was not related to eco-geographical distribution of provenances of a particular
region, but spread all over the clusters. Thus the geographical diversity can not
be used as an index to genetic diversity. Present results are inline with the
findings of Hooda et al. (2008). Therefore, hybridization involving
provenances of cluster IV and II is advisable in order to achieve high yielding
genotypes of J. curcas.
99
Discussion
Environmental Influence on Seed Germination
The present study was conducted to examine the germination behavoiur
of J. curcas as influenced by the seed size variation, environmental factors,
seed collection period, storage containers and storage duration. It is expected
that the study will provide reliable practical guidelines for the better
germination of J. curcas seeds.
In the present study, J. curcas showed wide variations in its seed size
and based on the size seeds were graded into three size classes viz., small (1315 mm), medium (15-17 mm) and large (17-19 mm). In bulk seed samples, the
proportion of seeds was highest in the medium seed size class. Khera et al.
(2004) have also observed maximum proportion of seeds in medium seed size
class in A. nilotica, A. lebbeck and D. sissoo. The length, width, thickness and
100-seed weight of seeds varied among the seed size classes. These characters
of seeds indicated an increasing trend from small to large seed size class. The
differences in seed size and weight within a sample may be due to variation
from plant to plant, which results from genetic or environmental differences or
developmental factors as suggested by Schmidt (2000).
The present investigation showed that seed size and weight affect the
germination (%) and other parameters of germination in J. curcas. Larger seeds
germinate better than smaller seeds in both the conditions, laboratory as well as
in field (Fig.7.3). Syam (1988) also reported that the large grade seeds of T.
grandis were superior in germination characteristics than the small grade seeds.
Seed weight showed a significant positive correlation (p<0.01) with the
germination (%), GV, SG and GE in both the conditions. However, this
relationship was more pronounced in field condition. Nizam and Hossain
(1999) have reported that in A. samen heavier seeds performed better than the
lighter seeds. Pathak et al. (1981) have also observed that the germination was
faster in large seeds than in small seeds in Leucaena leucocephala.
Arunachalam et al. (2003) have observed that in M. ferrea heavier seeds
100
Discussion
showed early and rapid germination. Singh (1998) reported that germination in
Quercus floribunda increased as the seed weight increased. Present findings
that germination behaviour is better in large and heavier seeds than the smaller
and lighter ones are also in conformity with the results of Girish et al. (2001)
for Sapindus trifoliatus; Sasthri et al. (2001) for Syzygium cuminii; Manonmani
and Vanangamudi (2002) for Santalum album; Suresh et al. (2003) for Bassia
longifolia; Khera et al. (2004) for Acacia catechu and A. nilotica and Ghildiyal
and Sharma (2005) for Pinus wallichiana. This may be attributed to the larger
food reserves with greater nutrient pool present in the endosperm of the heavier
seeds (Kandya 1978; Tripathi and Khan 1990). Farmer (1980) opined that
larger seeds have distinct advantage over the smaller seeds due to larger
embryo or gametophytic tissue, more cotyledon surface area or initial leaf area.
Larger seeds took less time to germinate and achieve a greater germination
percentage. This is probably because of the differences in seed content, such as
starch and proteins, which may be responsible for germination differences
among the seed size classes. This is in agreement with the previous reports on
other species, such as A. nilotica (Shaukat et al. 1999), Blutaparon
portulacoides and Panicum racemosum (Cordazzo 2002).
Although the germination (%) in large and medium sized seeds in J.
curcas did not show significant difference in laboratory, the seeds from these
two classes showed a lower significant variation in germination (%) than
between small and medium seeds in field condition. Thus, looking into the fact
that the germination (%) was also considerably higher in medium seeds than in
small seeds, the small seeds with the contribution of about 19 % (by number) in
the total seed sample may cause a decline in the overall germination of the seed
sample. Therefore, it is desirable to remove the seeds of J. curcas of the size
class below 15 mm from the bulk sample to ensure higher and uniform
germination of the total sample.
101
Discussion
Light quality, temperature and soil water supply are the most critical
environmental factors affecting the germination of seeds. The effect of these
environmental factors varies from species to species, therefore the optimum
conditions for each species need to be standardized. In the present
investigation, the initiation of germination was same under far-red and direct
light condition, however, under red light condition seed germination started
rapidly, whereas dark condition delayed the initiation of germination
maximally (Table-7.2). This indicates that the initiation of germination in J.
curcas is photo-controlled, since initiation of germination of this species in
light is greater than in dark. Initiation of germination in many species is
reported to respond to light quality (Toole 1973). Value of the relative seed
germination was maximum under far-red light condition (Table-7.2). It was
also observed that J. curcas indicated lower values for relative seed
germination under red light and dark condition.
Seeds of J. curcas showed maximum germination in far-red light
followed by direct and red light condition, while it was greatly reduced under
dark light condition (Fig.7.4). Kettenring (2006) also observed that exposure to
both white and red light significantly increased germination over the dark light
in the wetland Carex species. Kandari et al. (2008) have reported that this type
of seed germination is associated with phytochrome. They further pointed out
that in the species, which grows in open areas, the sensitivity of seeds to the
spectral quality of the light, mediated by phytochrome is a frequent natural
process. Since the environment under the tree canopy is reported to have a high
intensity of far-red light (Stoutjesdijk 1972), the greater germination under farred light condition indicates that this species can be regenerated successfully
under the tree cover as well as on exposed sites.
102
Discussion
Table-7.2: Relative delay in initiation of germination and relative seed
germination under different light conditions, temperature
regimes and water stress levels
Parameters
Relative delay in
initiation of
germination
Relative seed
germination
0.83
1.00
1.17
0.94
1.03
0.68
0.67
1.00
1.00
-
0.73
1.51
1.20
-
1.33
1.33
2.00
4.00
4.67
0.81
0.80
0.59
0.37
0.12
LIGHT QUALITY
Red
Far-red
Dark
TEMPERATURE (0 C)
22
27
32
37
WATER STRESS LEVELS (bar)
-4
-8
-12
-16
-20
‘–’ indicates failure of seed germination
Temperature regimes regulate seed germination by affecting reaction
rates and changes in the physical state of cellular components. In this study,
seeds of J. curcas did not show much difference in the initiation of germination
under different temperature regimes, except that the germination at highest
temperature (370 C) was zero (Table-7.2). Optimum temperature for
germination varies with species because at temperature optima, seed is biochemically very active and a minor fluctuations above and below, checks the
rate of biochemical activity which results in inhibition or slowing down of
germination (Thompson 1970). This is in close confirmation with the present
study, which showed that 270 C was the ideal temperature for germination of J.
curcas seeds, while at 220 C and 370 C there was less and no germination,
respectively (Fig.7.5). Same result was also reported by Shringirshi et al.
(2001) in A. indica, who also opined that temperature regimes regulate seed
103
Discussion
germination by affecting reaction rates. Our study shows that germination first
increased from lower to higher temperature and afterwards it declined and even
with further rise in high temperature germination did not occur. This may be
due to the fact that as the temperature rises, changes in protein conformation
occur, which actually promote the germination process, but further
conformational changes at very high temperature are deleterious to seed
germination (Bewley and Black 1985). Similar observations were also made
for Arnebia benthamii by Kandari et al. (2008). Kumar et al. (2007) have also
reported that lower and higher temperatures had adverse effect on germination
of A. indica. Kebreab and Murdoch (2000) have tested the effect of different
temperatures on the germination of Orobanche aegyptiaca seeds under 5-290 C
temperature and concluded that germination increased with increasing
temperature from 5-200 C and decreased above 260 C.
The relative seed germination was recorded higher at 27 0 C and 320 C
constant temperature regimes (Table-7.2). The germination (%) was, however,
low under alternating day/night temperature. As opposed to alternate
temperature regime, this species thus showed preference for high constant
temperatures of 270 C or 320 C. Favourable effect of constant temperature on
seed germination has also been reported by Tothill (1977).
Soil water supply is an important factor for controlling germination
(Come 1982). If the water potential of the imbibition medium is reduced,
germination may be delayed or even prevented, depending on the extent of
reduction in water potential (Hegarty 1978). Seeds of J. curcas indicated
relative delay in initiation of germination under different water stress level and
this delay in initiation of germination increased on increasing the water stress
level (Table-7.2). It was interesting to note that this species showed higher
relative delay in germination beyond – 8 bar water stress condition. Beyond – 8
bar, even a slight increase in water stress reduced the relative germination as
well as the initiation of germination (Table-7.2).
104
Discussion
In the present study increasing moisture stress reduced germination (%),
GV, SG and GE (Fig.7.6). These results of the present study are in conformity
with the findings of Sah et al. (1989); Falleri (1994); Kebreab and Murdoch
(2000); Pirdasthi et al. (2003) and Khera and Singh (2005). Reduction in seed
germination at higher levels of water stress may be ascribed to the moisture
deficit in the seeds below the threshold which may lead to degradation and
inactivation of essential hydrolytical and other groups of enzymes as suggested
by Wilson (1971). De and Kar (1995) have also observed that germination of
mung bean was declined with increasing water stress. However, the
germination was not inhibited even at highest level of water stress (- 20 bar) in
J. curcas.
It is further observed in the present study that the greater effect of
osmotic potential on the germination (%), GV, SG and GE occurred beyond -8
bar. Even the MGT did not show significant increase up to –8 bar water stress.
Similar trend was also reported by Barnett (1969). Thus, earlier and greater
germination with higher speed in J. curcas at water stress up to –8 bar could be
an advantage to better adaptation of this species to moderate water deficit areas.
The greater ability of J. curcas seeds to germinate under water stress should
also give an advantage when water stress often is severe during the periods
outside the rainy season or prolonged dry spell during rainy season.
Parrish and Bazzaz (1982) have observed that early successional species
are capable of occupying a greater habitat range thus showing a broader
response breadths on environmental gradients. However, among the various
environmental gradients, the seeds of J. curcas indicated maximum response
breadth under different conditions of light than under other environmental
gradient (Table-7.3). Thus, although J. curcas can tolerate wide range of light
quality, this species is tolerant upto low level of water stress and to certain
treatments under temperature.
105
Discussion
Table-7.3: Levins’s response breadth for J. curcas under different
conditions of light, temperature and water stress
Environmental
factors
Light
G (%)
GV
SG
MGT
GE
0.977
0.927
0.974
0.999
0.956
Temperature
0.750
0.651
0.771
0.798
0.754
Water stress
0.812
0.560
0.675
0.912
0.702
Different periods of seed collection affect the germination behaviour of
seeds of J. curcas. Present study shows that germination was greater in the
seeds collected and tested in April than in September. When the seeds were
collected and sown in the month of September, just before the onset of winter,
it has been observed that germination was slow and lateron survival of
seedlings was also low. According to Mughal et al. (2007) seeds sown in
November-December in the nursery get stratified during winter and starts
germination in spring season.
This study also reveals that seeds collected and sown in the month of
April complete their germination earlier than the seeds collected and sown in
September. It may be due to the environmental conditions like temperature and
moisture which were favourable during April to complete germination earlier.
Low survival in September is probably because of low temperature possibly
lead to damage the seeds as well as small germinants.
Successful regeneration of plants mainly depends on quality of seeds,
their viability and vigour, which ultimately depend on seed storage system for
their conservation (Sahai 1999). In the present study four types of storage
containers viz., paper bag, polythene bag, cloth bag and earthen pot were used
to find out the suitable one for the storage of J. curcas seeds. For this purpose,
proper sun dried healthy and highly viable seeds were kept in experimented
containers for 8 months. At the time of seed collection, the germination and
viability in J. curcas was 100 %. Hundred percent seed germination at the time
106
Discussion
of seed collection was also observed earlier by Purohit et al. (1996) in Butea
monosperma, P. pinnata and Terminalia bellerica and by Handa et al. (2006)
in P. pinnata.
Seed storage study of J. curcas indicated less viability with increase in
time interval and the experimented containers were not effective to store the
seeds for a long time. Seeds stored in different containers at room temperature
lost more than 50 % viability after 8 months storage. Loss of seed viability
even within a few months of storage at room temperature was also observed in
Salix setchellina (Douglas 1995) and poppy seeds (Verma et al. 1996). This
may be due to the activity of mycoflora present inside the seeds, which become
active when it gets optimal environmental conditions during storage. Thus, they
destroy the endosperm by utilizing it as their food material and render the seeds
non-viable. In the present study, among the different containers, seeds stored in
polythene bags and earthen pots were found to be more viable as compared to
the seeds stored in cloth bags or in paper bags. Similar observations were also
made by Handa et al. (2006) in P. pinnata. Minimum viability loss in the seeds
stored in polythene bags was also reported by Chauhan and Nautiyal (2007).
The potential storage life of seed varies from species to species
(Harrington 1972; Agarwal 1980) under the same storage condition. In this
study, storage container significantly influenced the germinability of J. curcas
seeds. Per cent seed germination significantly decreased in J. curcas with an
increase in storage duration. The seeds stored in polythene bags excelled all
other storage container witnessing the maximum values for the germination
parameters, whereas cloth bags and paper bags found to be least effective. This
is in line with the findings of Sivagnanam and Vanangamudi (1997) for the
seeds of A. indica. It may be ascribed to the higher rate of oxygen and vapour
transmission in cloth bags and paper bags than polythene bags and earthen pots.
Our results are also very close with the findings of Handa et al. (2006) for P.
pinnata. Bhardwaj et al. (2007); Naytial and Mehta (2003) and Raja et al.
107
Discussion
(2003) have also observed that polythene bag is the most effective storage
method registering the highest values for germination attributes.
Seeds stored in sealed container at room temperature gave better
germination (Purohit and Jamaluddin 2003; Pushpkar and Babeley 2001). Thus,
seeds stored in polythene bags showed superiority in germination, might be due
to imperviousness against moisture loss in polythene bags. Since moisture loss
is the chief cause of deterioration of seeds under storage conditions (Harrington
1963), superiority of moisture impervious containers was advocated earlier also
(Verma et al. 1996).
Seedling Growth in Nursery
Grading of seeds according to their size is a useful practice for the
production of evenly growing crop of seedlings in the nursery. The effect of
variation in seed size on the seedling growth was examined by grouping the
seeds into large, medium and small sizes on the basis of their seed size. In the
present study seed size showed a significant positive correlation (p<0.01) with
seedling growth and dry weight. It was observed that growth and dry weight
were recorded higher for the large and medium seeds as compared to smaller
seeds. It may be because of larger embryo with greater reserve of nutritional
matter, the seedlings from large seeds showed better growth and dry weight
than those from small seeds (Kaufmann and Guitard 1967; Ponnuswamy et al.
1991). According to Tripathi and Khan (1990), greater reserve in heavy seeds
may allow for the better pre-photosynthetic growth of the seedlings, which in
turn may contribute for the better growth and survival of seedlings. Khan
(2004) found a positive correlation between seed size and seedling growth in
Artocarpus heterophyllus, and the same relationship was also observed for
seedlings of 14 Oak species by Long and Jones (1996). Higher plant growth
and dry weight of seedlings from large and heavy seeds is also in accordance
with the findings for L. leucocephala (Gupta et al. 1983), A. samen (Nizam and
108
Discussion
Hossain 1999), B. longifolia (Suresh et al. 2003), A. nilotica and for A. lebbek
(Khera et al. 2004).
The total height per unit dry weight of stem decreased as the seed size
increased. On the other hand, the values for NAR and SQ of the seedlings
increased with increasing seed size, thus showing a similar pattern as observed
for height, collar diameter and total seedling dry weight. In the present study
seedlings raised from smaller seeds have higher RGR than those from larger
seeds. It is consistent with the other studies on RGR by Jurado and Westoby
(1992) and Reich et al. (1998). The negative relationship between seed size and
RGR can be related to lower photosynthetic area per photosynthetic mass, as
seedlings get larger, the fraction of mass in photosynthetic tissue declines (i.e.,
leaf mass ratio declines), leading to decrease in RGR (Walters et al. 1993).
It is clear from the present study that the seedlings raised from small
seed size class produced small growth features and low dry weight. Thus, it
appears desirable to select the medium and large seeds for faster growth of
seedlings of J. curcas. These larger seedlings should also be preferred for
plantation programmes, which may result in higher survival and growth rate in
plantations.
Several workers (Koul et al. 1995; Singh et al. 2001) have advocated the
balance and complementary use of fertilizers to maximize the growth and
biomass production of seedlings in nursery.
In the present study, the
application of NPK fertilizers @ 100:75:75 mg per seedling in soil indicated
maximum improvement in growth, dry weight and QI of J. curcas seedlings
over the control (Table-7.4). The increase in growth and dry weight in response
to NPK application has also been observed in the seedlings of certain other
species (Singh and Banerjee 1999; Singh et al. 2001; Basavaraj et al. 2006). In
J. curcas, the application of N in higher doses reduced the seedling growth and
dry weight (Table-7.5). Bhardwaj et al. (1996) in Acer oblongum, Singh and
Banerjee (1999) in A. procera, Bhuiyan et al. (2000) in Casuarina equisetifolia
109
Discussion
Table-7.4: Relative performance of six month old seedlings of J. curcas
under different levels of fertilizers (proportion to control)
N:P:K (mg seedling-1)
Parameters
Control
100:25:25
100:50:50
100:75:75
200:25:25
200:50:50
200:75:75
300:25:25
300:50:50
300:75:75
Seedling height
1.00
1.92
1.99
2.00
1.80
1.85
1.89
1.61
1.70
1.74
Collar
diameter
No. of
leaves/seedling
Leaf dry
weight
Stem dry
weight
Shoot dry
weight
Root dry
weight
Total dry
weight
Quality
Index (QI)
RGR
1.00
1.26
1.17
1.13
1.31
1.09
1.42
1.26
1.34
1.34
1.00
2.27
2.60
3.20
1.80
2.00
2.07
1.53
1.60
1.67
1.00
4.18
6.98
7.89
3.22
3.70
3.92
2.14
2.45
2.61
1.00
2.17
2.49
2.72
1.65
1.80
1.91
1.35
1.49
1.65
1.00
2.27
2.72
2.98
1.73
1.90
2.01
1.39
1.54
1.70
1.00
2.96
3.21
3.96
1.98
2.30
2.39
1.42
1.55
1.84
1.00
2.47
2.86
3.27
1.79
2.01
2.12
1.39
1.54
1.74
1.00
2.09
2.18
2.49
1.56
1.55
1.91
1.22
1.35
1.54
1.00
0.83
0.91
0.87
0.78
0.83
0.83
0.91
0.78
0.87
NAR
1.00
0.65
0.68
0.61
0.63
0.65
0.63
0.88
0.65
0.71
LWR
1.00
1.71
2.47
2.44
1.82
1.85
1.88
1.56
1.59
1.53
RWR
1.00
1.20
1.13
1.21
1.10
1.15
1.13
1.01
1.00
1.06
Table-7.5: Effect of nitrogen on seedling growth and dry weight of J.
curcas expressed as proportion of control (values are arranged
across P and K)
N (mg seedling-1)
Parameters
Control
100
200
300
Seedling height
1.00
1.97
1.85
1.68
Collar diameter
1.00
1.19
1.27
1.31
Shoot dry weight
1.00
2.66
1.88
1.55
Root dry weight
1.00
3.37
2.22
1.60
Total dry weight
1.00
2.87
1.98
1.56
Quality Index (QI)
1.00
2.25
1.67
1.37
and Tewari and Saxena (2003) in D. sissoo have also observed that higher
doses of N application decreased the growth of seedlings. Lack of positive
110
Discussion
response to higher doses of N can be attributed to the initial status of available
nitrogen in the experimental soil which when supplemented with 100 mg N
might have reached at supraoptimal level of plant nitrogen requirements. Many
workers have studied the role of nutrients on seedling growth and they found
that requirement varies with the type of the soil medium used (Rangaswamy et
al. 1990). Unlike the N, effect of P and K in highest doses (@ 75 mg per
seedling) was found maximum for the production of seedling dry weight in J.
curcas, may be because of their low initial status in the experimental soil.
The type of soil mixture significantly influenced the growth, dry weight
and quality of J. curcas seedlings. The effect of soil mixtures on the growth
and quality of seedlings of various tree species has also been reported earlier
(Ginwal et al. 2002; Tewari and Saxena 2003; Srivastava et al. 2006). Among
all the soil mixtures, seedlings of J. curcas indicated higher growth and dry
weight in the mixture of soil, sand and FYM in 1:2:2 and 1:1:2 ratios (Table7.6). It may be because of the fact that the water holding capacity of FYM is
always greater than the sand and soil alone or in combination (Nayital et al.
1995). Additionally the FYM also improves physical status of soil and nutrient
uptake (Kaberathumma et al. 1993). Thus, the increase in FYM in the soil
mixture favours the seedling growth. Similar results were also observed for A.
nilotica (Singh et al. 2000), A. procera (Ginwal et al. 2004), Albizia amara
(Handa et al. 2005) and Picea simithiana (Lavania et al. 2007). However, the
increase of sand in the soil mixture beyond 1:2:2 ratio of soil, sand and FYM
was not much beneficial to the growth of the J. curcas seedlings. This is in
conformity with the findings of Tewari and Saxena (2003) for D. sissoo
seedlings. Higher proportion of sand in the soil mixture reduces the water
holding capacity and thus inhibits the seedling growth. Further, the soil mixture
with high proportion of sand lacks aggregation due to which the container soil
gets dispersed at the time of planting leaving the seedlings naked and may
result in poor survival. Besides this, sandy medium remains loose due to
111
Discussion
Table-7.6: Relative performance of six month old seedlings of J. curcas in
different mixtures of soil, sand and FYM
(proportion to control)
Parameters
Soil mixture (soil: sand: FYM)
1:0:0
1:1:0
1:1:1
1:1:2
1:2:0
1:2:1
1:2:2
1:3:0
1:3:1
1:3:2
Seedling height
1.00
1.11
1.92
2.64
1.64
2.22
2.85
1.04
1.32
1.53
Collar diameter
1.00
1.39
1.50
2.17
1.67
1.75
2.08
1.25
1.42
1.75
No. of
leaves/seedling
Leaf dry weight
1.00
1.25
2.00
2.50
1.75
1.92
4.08
1.17
1.42
1.75
1.00
1.94
1.53
2.80
1.98
2.47
4.69
1.05
1.67
1.47
Stem dry weight
1.00
1.60
2.71
3.48
2.19
2.64
3.76
1.30
2.09
2.36
Shoot dry weight
1.00
1.64
2.55
3.40
2.17
2.64
3.91
1.26
2.03
2.22
Root dry weight
1.00
2.32
3.38
3.99
2.48
3.50
4.64
1.71
2.49
2.92
Total dry weight
1.00
1.82
2.76
3.54
2.24
2.76
3.95
1.38
2.15
2.42
Quality Index (QI)
1.00
2.44
2.84
3.54
2.44
2.86
3.86
1.78
2.49
2.98
RGR
1.00
0.88
1.00
1.00
0.82
0.94
1.00
0.94
0.94
1.11
NAR
1.00
0.85
0.94
0.88
0.88
0.85
0.85
1.29
1.44
1.85
LWR
1.00
1.06
0.55
0.79
0.88
0.89
1.15
0.76
0.78
0.61
RWR
1.00
1.27
1.22
1.13
1.11
1.27
1.14
1.23
1.16
1.21
disproportionate amount of sand that dries out readily and also promotes the
leaching of nutrients (Lavania et al. 2007) resulting in the poor growth of
seedlings.
Soil moisture is the important aspect of plant environment affecting
almost all the vital physiological processes. Plant response to water has been
investigated by Gill et al. (1983). The results indicated that providing irrigation
has positive effect in increasing the height of seedlings. Since the long dry
spells are common outside the rainy season, the study on the growth responses
of J. curcas on soil moisture gradient would be very useful. The seedlings of J.
curcas performed relatively better under control (irrigation at one week
interval) and low moisture stress condition (irrigation at two week interval)
than under intermediate or high moisture stress conditions (Table-7.7). The
112
Discussion
reduction in growth and dry weight of seedlings under intermediate and high
soil moisture stress levels was also reported by Osmond et al. (1980) and
Bheemiah (2004) for certain other species. Under these conditions, the
seedlings might have suffered with low moisture availability, which in turn
have checked the proper growth of seedlings through the lack of turgidity and
cell extension. The decrease in growth under intermediate and high moisture
stress conditions may also be due to a decline in net assimilation by decreasing
water potential in leaves (De Puit and Caldwell 1975) and increased respiration
(Kramer 1969). It is interesting to note that root:shoot ratio in J. curcas had an
inverse relation with the growth and dry weight parameters of seedlings.
Root:shoot ratio increased with increasing the levels of moisture stress.
According to Harper (1977) root growth is dependent on shoot growth and
root:shoot ratio changes with environmental treatment.
Table-7.7: Relative performance of six month old seedlings of J. curcas
under different levels of moisture stress (proportion to control)
Parameters
Seedling height
Collar diameter
No. of leaves/seedling
Leaf dry weight
Stem dry weight
Shoot dry weight
Root dry weight
Total dry weight
Quality Index (QI)
RGR
NAR
LWR
RWR
Moisture stress levels
Control
Low
Intermediate
High
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
0.95
0.95
0.95
0.97
0.84
0.87
1.40
0.94
1.27
1.02
1.13
1.04
1.49
0.76
0.75
0.86
0.82
0.57
0.63
1.43
0.73
1.18
0.97
0.96
1.13
1.95
0.64
0.65
0.67
0.72
0.24
0.36
1.68
0.53
1.16
1.05
1.43
1.36
3.19
The response of J. curcas seedlings to various soil sodicity levels
indicated marked reduction in growth and dry weight parameters of the
seedlings with increasing levels of sodicity (Table-7.8). The values for growth,
113
Discussion
dry weight and QI of the seedlings did not show much variation up to low
sodicity level, thus indicating tolerance of J. curcas seedlings up to low
Table-7.8: Relative performance of six month old seedlings of J. curcas
under different levels of sodicity (proportion to control)
Parameters
Seedling height
Collar diameter
No. of leaves/seedling
Leaf dry weight
Stem dry weight
Shoot dry weight
Root dry weight
Total dry weight
QualityIndex (QI)
RGR
NAR
LWR
RWR
Sodicity levels
Control
Low
Intermediate
High
Very high
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
0.91
0.86
0.91
0.82
0.82
0.82
0.86
0.83
0.83
0.99
1.04
0.98
1.34
0.81
0.77
0.82
0.65
0.58
0.60
0.74
0.62
0.69
0.93
1.28
1.48
2.59
0.49
0.67
0.55
0.47
0.23
0.30
0.41
0.32
0.44
0.88
3.13
1.04
1.75
0.29
0.48
0.32
0.09
0.03
0.04
0.26
0.08
0.28
0.51
1.18
1.05
0.87
sodicity level. However, under intermediate and higher levels of soil sodicity
the values for all the seedling growth and dry weight parameters were markedly
reduced indicating poor tolerance of this species to these soil sodicity levels.
These findings are in conformity with the earlier findings of Singh and Yadav
(1999); Singh (2000) and Tewari et al. (2006). The values for root:shoot ratio
increased with an increase in sodicity levels. The higher root:shoot ratio in this
species at higher levels of sodicity appear to be an adaptive strategy to increase
the ratio of water absorbing to water transpiring organs as reported by
Bernstein (1975).
The seedling growth, dry weight and QI in J. curcas showed wider
responses on all the environmental gradients (Table-7.9). Parrish and Bazzaz
(1982) have observed that early successional species are capable of occupying
a greater habitat range thus showing broader response breadths on
environmental gradients. However, among the various environmental gradients,
the seedlings of J. curcas indicated lower response breadth on sodicity gradient
114
Discussion
than under other environmental gradient. Thus, although J. curcas can tolerate
any treatment under soil mixture, fertilizer doses and moisture stress level, this
species is tolerant upto low sodicity only. Further, our values for response
breadth on sodicity gradient were lower than the values reported for A. nilotica
and higher than the values reported for D. sissoo (Tewari et al. 2006). This
indicates higher tolerance of J. curcas seedlings than those of D. sissoo
seedlings but lower tolerance than A. nilotica seedlings on sodicity gradient.
This may be due to the difference in root behaviour and hardiness of this
species to such adverse soil environment (Singh 1994).
Table-7.9: Responses breadth for J. curcas seedlings on different gradients
of soil mixtures, fertilizer doses, moisture and sodicity.
Parameters
Seedling height
Collar diameter
Leaf weight
Stem weight
Root weight
Total dry weight
Quality Index
Fertilizer
doses
Soil mixtures
Moisture stress levels Sodicity levels
0.966
0.882
0.971
0.874
0.990
0.966
0.972
0.948
0.770
0.787
0.983
0.789
0.909
0.861
0.841
0.682
0.874
0.885
0.970
0.847
0.906
0.886
0.949
0.746
0.936
0.919
0.993
0.860
Present study showed that season of taking cuttings, their diameter and
auxin concentrations influenced the rooting, sprouting and growth behaviour of
seedlings raised through stem cuttings of J. curcas considerably. Bhatt and
Todaria (1990) have also reported that seasonal stimulus plays an important
role in root formation. Untreated cuttings taken in February exhibited better
rooting and sprouting than the cuttings taken in May, whereas July planted
cuttings showed poor rooting and sprouting. The seasonal periodicity of rooting
in stem cuttings associated with the growth phase has also been reported for
other species by Capuana and Lambardi (1995). Although auxin application
was unable to overcome this periodicity in rooting and sprouting, it increased
the rootability and sprouting of cuttings and this increase over the control was,
115
Discussion
in general, greater in May, i.e., during the period of higher vegetative growth. It
seems that the cuttings made in May are rich in carbohydrates and with the
exogenous application of auxins, rooting in the cuttings increased. A number of
workers have reported that rooting of cuttings is facilitated when carbohydrate
reserve foods are in abundance (Hartmann 1962; Nanda and Dhaliwal 1974;
Puri and Khara 1992). Further, auxin induced the rooting considerably during
February but induced rooting poorly during July. Increase in rooting due to
auxin in February planted cuttings may be due to the increasing temperature
and cambial activity resulting in mobilization of reserve food materials to the
site of root initiation as suggested by Bala et al. (1969); Purohit (1986) and
Gurumurti et al. (1984). The auxin treated cuttings, planted in February showed
higher root, shoot growth, dry weight and quality of seedlings than the May
planted cuttings. It seems that the level of endogenous auxins and other rooting
factors increased during February after the leaf fall or bud breaking stage
(February-March) in J. curcas, which subsequently activates the cambium and
the plant factors associated with rooting as suggested by Palanisamy and
Kumar (1997). Dhillon et al. (2006) in J. curcas also observed highest rooting
and sprouting in spring season as compared to the monsoon season.
Study shows that rooting, sprouting, vegetative growth, dry weight and
QI of the seedlings increased with increasing diameter of cuttings in control
treatment (Table-7.10). Although IBA increased the rooting, sprouting, growth,
dry weight and QI in all the cuttings, the maximum rooting percentage, root
length and root dry weight was observed in the cuttings with largest diameter
treated with IBA 1000 ppm, while the cuttings with similar diameter treated
with IBA 500 ppm indicated greater values for other growth and dry weight
parameters. Rawat (1986) and Tewari (2001) have reported that root formation
in cuttings is controlled by cutting diameter. This variation in rooting and
116
Discussion
Table-7.10: Effect of cutting diameter on rooting, sprouting and vegetative
growth of three month old seedlings of J. curcas raised from
stem cuttings (average across different season and auxin
concentrations)
Parameter
Rooting (%)
Sprouting (%)
No. of sprouts/cutting
Collar diameter
Stem height
Root length
Total dry weight
3 mm
5 mm
7 mm
control
IBA
NAA
control
IBA
NAA
control
IBA
NAA
34.4
37.5
1.1
4.3
1.6
2.6
0.7
33.0
39.6
1.4
4.7
2.9
3.5
1.0
1.7
9.4
0.3
1.3
0.6
1.2
0.1
41.7
43.3
1.3
4.7
8.6
3.2
1.2
47.6
52.3
1.8
5.6
9.2
4.5
2.4
23.5
31.6
0.6
3.0
2.4
1.8
0.3
46.8
46.5
2.9
8.0
12.7
5.1
2.5
57.6
70.4
3.7
8.3
12.8
5.3
4.1
25.7
31.6
1.8
4.2
4.7
3.1
0.9
growth behaviour of the cuttings with different diameter may be due to
differential physiological status of the cuttings.
The rooting, sprouting and growth response of seedlings were also
affected by different type of auxins in different concentrations (Table-7.11). It
has been suggested that optimum concentration of auxin is favourable for the
growth of seedlings rooted through stem cuttings. In the present study, lower
concentration of IBA was found to be more effective than higher concentration
of IBA for the production of greater dry weight of the seedlings. However,
Table -7.11: Effect of auxin on rooting, sprouting and vegetative growth of
three month old seedlings of J. curcas raised from stem cuttings
(average across different season and cutting diameter)
Parameter
Rooting (%)
Sprouting (%)
No. of sprouts/cutting
Collar diameter
Stem height
Root length
Total dry weight
control
IBA 500
IBA1000
IBA 2000
NAA 1000
NAA 2000
41.0
42.4
1.7
5.6
6.9
3.6
1.4
49.1
62.3
3.0
7.7
11.9
5.2
3.8
57.8
51.8
2.5
6.0
7.4
4.9
2.7
31.0
38.1
1.6
4.9
4.1
3.1
1.5
21.4
29.9
1.2
4.0
3.9
2.9
0.7
12.5
18.4
0.6
1.7
1.2
1.1
0.2
rooting percentage, root dry weight and seedling QI were higher on treating the
cuttings with slightly a higher concentration of IBA i.e., IBA 1000 ppm. On the
contrary, IBA at 500 ppm is the best and most efficient auxin for the
117
Discussion
stimulation of sprouting and growth behaviour of J. curcas. Similar results
have also been found in case of T. grandis (Nautiyal et al. 1991) and Taxus
baccata (Aslam et al. 2007). According to Nanda (1970) and Haissing (1979),
depending on the endogenous level of growth regulating substances, exogenous
application of auxin may be promotive, ineffective or even inhibitory for
rooting of cuttings. Thus, the much higher concentration of auxins applied to
the cuttings might be supraoptimal for inducing the rooting in cuttings.
Superiority of IBA as rooting hormone to that of others auxin has also
been well documented by Parthiban et al. (1999) and Jagatram et al. (2002).
The action of auxin activity might have accumulated cell elongation and cell
division along with suitable environment which might have helped in
increasing the growth process of the seedlings.
The concentration of hormone is an important factor in rooting of cuttings
(Nautiyal et al. 1991). Although, auxin helps in rooting and growth behavoiur
but only upto a certain limit. If intolerable higher concentration is given, it may
results into inferior growth (Hartmann and Kester 1983). It was also observed
in the present study, that shoot length decreases with increasing concentration
of IBA but rooting percentage, root length and root dry weight were maximum
in IBA 1000 ppm. Husen and Mishra (2001) also reported that the level of
auxin is favourale for root growth may not be suitable for better shoot growth.
Plantation Management
This study was undertaken to examine the effect of various management
practices on the vegetative growth and yield of fruits and seeds of J. curcas
planted on sodic land. The study shows that plant spacing, different levels of
pruning, irrigation, fertilizer, organic manuring and weeding influenced the
plant growth and production of fruits and seeds in J. curcas.
The plantation of species should be made at such spacing at which they
fulfill the purpose of plantation by achieving their maximum growth, flowering
and fruiting. Performance of plants at different spacing has been examined
118
Discussion
earlier for different species like, Albizia chinensis (Nayital et al. 2006),
Populus deltoides (Kumar et al. 2008) and Gmelina arborea (Singh et al.
2008). In the present study, maximum number of branches, fruit and seed yield
was recorded in the plants under 3 x 4 m spacing. The values for these
parameters decreased on either decreasing or increasing the spacing between
the plants. Thabet (2007) also reported that higher or lower plant spacing had a
negative effect on seed yield. Thus, the plantation of J. curcas with better
growth and yield production, depends on the spacing between the plants. Study
also showed that wider spacing increased the vegetative growth (except plant
height) and yield of this species, may be due to certain congenial conditions
like, light, space and less competition for soil water and nutrients. Maximum
canopy spread was observed for the plants established at 4 x 4 m spacing.
Plant architecture plays an important role in a plant like J. curcas, where
proper pruning will ultimately increase the yield. The present study shows a
positive impact of pruning on growth and yield parameters. Among the three
pruning levels of main shoot, plants pruned at 1 m showed the maximum
values for all the parameters except for the collar diameter followed by 75 cm
and 50 cm, while among the different pruning intensity of side branches, plants
pruned with 50 % exhibited maximum number of branches and yield of fruits
and seeds. Pruning also had a pronounced effect on collar diameter. As the
pruning height decreased, the collar diameter of the plants increased. The collar
diameter also increased when the pruning length of side branches increased.
The increase in collar diameter might be due to translocation and storage of
assimilates in the lower portion of stem (Patil et al. 2006). In the present study,
number of branches increased in pruned plants, which is in agreement with the
findings of Ali et al. (2001) and Vesilenko (1991). The number of branches is
important factor, because the inflorescence develops only at the end of
branches. The plants pruned at 1 m of main shoot and 50 % length of the side
branches showed maximum yield of fruits and seeds. It may be because of the
119
Discussion
fact that this treatment also indicated maximum number of branches and
canopy spread which ultimately contributed for the greater production of fruits
and seeds. Narkhede et al. (2008) stated that on reducing the number and length
of scaffold branches fruit yields on the remaining branches increased. Studies
on plant response to pruning treatments have also been conducted earlier on
different species viz., Grewia ariatica (Ali et al. 2001), Mangifera indica (Lal
and Mishra 2008), A. procera (Singh et al. 2008), Hardwickia binnata,
Anogesissus pendula and A. latifolia (Handa et al. 2008).
Water management as an important plant growth factor has been well
recognized earlier. Present results showed significant differences among the
growth and yield factors of J. curcas as a consequence of application of various
frequency of irrigation. On increasing the irrigation frequency the plant height
and collar diameter in J. curcas increased (Table-7.12). Increase in plant height
Table-7.12: Performance of J. curcas under different levels of irrigation
(proportion to control)
Parameters
Height
Collar diameter
No. of branches/plant
Canopy spread
Fruit yield
Seed yield
Different levels of irrigation
Control
Low
Intermediate
High
1.0
1.0
1.0
1.0
1.0
1.0
1.5
1.1
1.7
1.4
1.9
1.5
1.9
1.2
2.7
1.7
4.2
3.6
2.1
1.4
2.4
1.5
3.4
2.1
on increasing the level of irrigation was also reported by Troup (1989) and
Bheemiah (2004) for certain other species. This might be due to increased
availability of nutrients and better translocation of solutes. Collar diameter
increase on increasing the irrigation level was also reported by Bheemiah et al.
(1997). In contrast to the plant height and collar diameter, the maximum
number of branches and yield of fruits and seeds were observed under
intermediate level of irrigation (Table-7.12). These results are in accordance
with the findings of Chandel and Singh (2006).
120
Discussion
Several workers including Jan et al. (2000), Sharma et al. (2001) and
Ahmed et al. (2001) have suggested the use of fertilizers in adequate quantity
to maximize the growth and yield of plants. Parker and Pallardy (1988)
and Sciler and Cazell (1990) have observed that tree growth has been adversely
affected by inadequate amount of nutrients. In the present study, the
application of fertilizer @ 25g N + 25g P + 15g K + 20g S plant -1 exerted the
maximum growth and yield in J. curcas (Table-7.13). It is also observed that
Table-7.13: Performance of J. curcas under different fertilizer levels
(Proportion to control)
N,P,K,S (g plant-1)
Parameters
Height
Collar diameter
No. of branches/plant
Canopy spread
Fruit yield
Seed yield
Control
25:25:15:20
50:50:30:40
75:75:45:60
1.0
1.6
1.5
1.3
1.0
1.5
1.3
1.3
1.0
2.2
2.0
1.7
1.0
1.4
1.3
1.2
1.0
4.4
2.2
1.6
1.0
3.5
2.0
1.5
plants with no application of fertilizers showed lowest growth and yield. The
increase in growth and yield due to application of fertilizers has also been
recorded in other species (Nayital et al. 2006; Hussain et al. 1986; Koul et al.
1995). In J. curcas each increasing level of fertilizer, however, showed a
significant decrease in growth and yield. The decline in growth and yield under
higher doses of fertilizer may be due to toxic effect of high nutrient
concentration. High nutrient availability is also reported to have toxic effects
on some other species (Musik 1978).
Different type of organic manures helped in early establishment of J.
curcas in the field by promoting the vegetative growth. The beneficial effect of
organic manure was well demonstrated by a number of workers (Naik and Hari
Babu 2001; Ansari 2008; Mahesh Babu et al. 2008). The application of organic
121
Discussion
manure highly increased the plant height, collar diameter, number of branches
and yield of fruits and seeds in J. curcas (Table-7.14). This may be due to
additive effect of organic manures, which is in agreement with the report of
earlier workers (Mahesh Babu et al. 2008). These workers have demonstrated
that organic manures provide a good substrate for the growth of microorganisms and maintain a favourable nutritional balance and soil physical
properties, which ultimately help in the growth and productivity of plants.
Among the various organic manures applied in the present study,
vermicompost was found better for increasing the growth and yield of fruits
and seeds than FYM and leaf manure (Table-7.15).High vegetative growth in
vermicompost treated plants maybe because of fact that vermicompost contains
Table-7.14: Performance of J. curcas under different organic manures
(Proportion to control)
Organic
manures
(kg plant-1)
Parameters
Height
Collar
diameter
No. of
branches/
plant
Canopy
spread
Fruit yield
Seed yield
Control
1.0
1.0
1.0
1.0
1.0
1.0
FYM – 5
1.2
1.1
1.1
1.2
1.3
1.3
FYM – 10
1.2
1.1
1.8
1.5
2.2
2.1
FYM – 15
1.3
1.2
2.3
1.7
2.8
2.8
V.C. – 3.5
1.3
1.2
2.1
1.5
2.3
2.5
V.C. – 7.0
1.6
1.3
2.6
1.6
3.1
3.0
V.C. – 10.5
1.8
1.3
2.6
1.8
3.9
3.3
L. M. – 2.5
1.1
1.0
1.0
1.0
1.0
1.1
L. M. – 5.0
1.1
1.1
1.5
1.2
1.4
1.4
L. M. – 10.0
1.2
1.1
1.6
1.4
1.7
1.6
adequate quantities of NPK and several micro-nutrients essential for plant
growth. The role of the vermicompost in promoting the growth of plants was
also reported by Lalitha et al. (2000) and Raj Khowa et al. (2000). The
application of FYM also increased the growth of plants over the control, but
122
Discussion
comparatively lower increase when compared with vermicompost. Mahesh
Babu et al. (2008) have suggested that the beneficial effect of FYM was
exhibited only when it was applied in combination with chemical fertilizers.
Table-7.15: Effect of vermicompost, FYM and leaf manures on growth
and yield of J. curcas (average across the treatments of same
organic manures)
Organic
Parameters
manures
Height
Collar
No. of
Canopy
diameter
branches/
spread
Fruit yield
Seed yield
plant
Control
1.5
60.0
6.0
60.1
34.8
12.9
FYM
1.92
71.6
10.9
87.8
74.8
27.4
V.C.
2.42
75.9
14.9
100.5
109.0
38.2
L. M.
1.71
65.9
8.7
76.5
49.9
18.6
Results indicated that the fruit and seed yield was about three times
greater under vermicompost treatment than in the control treatment. This
increase in yield may be because that vermicompost improves the physical,
chemical and biological properties of soil and usually contains higher levels of
most of the mineral elements, which are in available forms for the plants.
Similar findings have also been reported by Naik and Hari Babu (2001); Ismail
(2005) and Ansari (2008).
Weeding is one of the most important cultural practices for successful
growth of the plantation crops. Presence of weed reduced the growth and yield
of plants (Turk and Tawaha 2001). In the present study, the growth and yield
of
J.
curcas
increased
as
the
weeding
frequency
increased
(Table-7.16).Adenawoola et al. (2005) have also reported that growth and yield
of plantation crops were positively correlated with the frequency of weeding.
Weeds deprive plantation crops of nutrients and water, thereby decreasing the
123
Discussion
Table-7.16: Performance of J. curcas under different weeding frequency
(proportion to control)
Parameters
Height
Collar diameter
No. of branches/plant
Canopy spread
Fruit yield
Seed yield
Weeding frequency
Control
Low
Intermediate
High
1.0
1.0
1.0
1.0
1.0
1.0
1.1
1.0
1.1
1.0
1.3
1.2
1.3
1.1
1.4
1.3
1.8
1.7
1.3
1.2
1.6
1.4
2.4
2.3
growth of plantation crops. Twomlow and Dar (1997) have observed that
through competition for nutrients, weeds can reduce the growth and yields of
maize by influencing the availability of soil water.
124