Effect of Seed Production Environment and Time of Harvest on Tomato (Lycopersicon esculentum) Seedling Growth
Anna M. Ashirov
This study was carried out to find out the effects of
two growing seasons and harvest time on seedling growth in tomato. Seeds
were harvested between 40, 45, 50, 55, 60, 70, 80 and 90 DAA (days after
anthesis) in spring and 45, 50, 55, 60, 70, 80, 90, 100 and 115 DAA in
autumn season from hybrid tomato plants grown under glasshouse. Maximum
seed weight occurred at 50 DAA in spring but went up to 80 DAA in autumn
season. Maximum seedling emergence took place at 60 DAA in spring as 89%
but 115 DAA as 90% in autumn. The highest seedling fresh and dry weights
were also observed at the same harvests. As seeds matured the fewer seeds
were germinated but unable to emerge in the compost. Advancement in seed
maturation not only increased seedlings fresh and dry weight but also
seedling uniformity (R2 = 0.75, R2 = 0.69) measured
through coefficient of variation (CV). Fast emergence (lower mean time
to emerge) resulted in the higher seedling fresh weight (R2
= 0.80, R2 = 0.84). Occurrence of maximum seedling quality
in tomato was influenced by the growing environment. Low greenhouse temperatures
in autumn delay occurrence of the maximum seedling growth up to 115 DAA.
While, it can be obtained from seeds harvested at 60 DAA in spring.
Physiological quality of seed lot is the result of pre-storage factors,
acquisition of the ability to produce vigorous seeds and post-storage
factors (Powell et al., 1984). Mother plant environment affects
seed quality through climate and growth conditions (Delouche, 1980).
Hybrid summer crop seeds are produced in two seasons, i.e., spring and
autumn under glasshouse or plastic tunnels in the Mediterranean basin
(Passam and Khah, 1992). Two serial seed production seasons provides more
profitable use of glasshouse field and produce more seeds within the same
year. The growing temperature in spring gradually increases during the
seed filling period (April-June) towards summer, contrarily, in autumn;
it declines as seed maturation progresses on the plant (October-December)
towards winter. It has been reported in various crop seeds that temperature
during the critical growth stage, i.e., the seed filling period, has affected
the seed yield and quality (Kameswara Rao and Jackson, 1996; Spears et
al., 1997; Craufurd et al., 2002; Thomas et al., 2003;
Greven et al., 2004; Demir et al., 2004). When produced
under warmer conditions, storage longevity of rice (Ellis et al.,
1993) and watermelon (Demir et al., 2004) seeds were shown to be
less than that from cooler environments. Warm climate also reduced the
seed dry mass in both species. Similarly, soyabean and bean seeds produced
at high temperatures during seed filling were smaller, wrinkled and poor
quality (Siddique and Goodwin, 1980; Spears et al., 1997). Occurrence
of low quality was more prominent particularly when high temperature was
combined with high relative humidity which is called field weathering
(TeKrony et al., 1980).
Although not an environmental factor, harvest time is known to be a major
factor responsible for physiological maturation level, size and vigour
of seed during maturation (Delouche, 1980). The decision of when to harvest
particularly under varying environmental conditions is therefore of importance
to get maximum seed quality. Various studies examining the influence of
seed development on seed quality in tomato have shown that seeds extracted
from fruits harvested 70-75 days after anthesis (Berry and Bewley, 1991;
Demir and Ellis, 1992; Liu et al., 1996) or when fruits are firm
red (Valdes and Gray, 1998; Demir and Samit, 2001; Ramirez-Rosales et
al., 2004) had the maximum viability and vigour. Although growing
environment was not considered in these studies, environment and seed
maturation may co-interact and time of occurrence of maximum quality may
change. Moreover, changes in transplant quality, in relation to environment
during seed development on the plant are valuable information for horticultural
technology. Protected tomato cultivation by and large was done by using
high value hybrid seeds. Therefore, high emergence percentage, uniform
and developed transplant production has utmost importance (Cantliffe,
The objective of this study was then to evaluate effects of temperature
during the seed filling period, on capacity of seedling growth in serially
harvested hybrid tomato seeds in two consecutive growing seasons (spring
and autumn) under glasshouse.
MATERIALS AND METHODS
Plant Husbandry and Seed Harvest: Plants were grown between February
and July 2005 in spring and between August 2005 and February 2006 in autumn
season. Seeds of male and female parent lines of hybrid tomato cultivar
(Lycopersicon esculentum Mill.), Safir (Anamas Seed Company/Antalya/Turkey)
were sown in seedling trays on 15 February and 21 August 2005 in spring
and autumn season, respectively. Seedlings were transplanted to the glasshouse
on 13 March and 12 September. Male and female lines were planted in the
same glasshouse with spacing of 80 cm between and 40 cm within rows. Ratio
of male to female plants was arranged as 1:4 and male parent plants were
isolated by using insect-proof plastic nets. Ammonium sulphate (15 kg/1000
m2) and potassium nitrate (15 kg/1000 m2) were applied
at transplanting and again at the seed filling phase (15 days after anthesis)
via watering. Drip irrigation was applied and approximately 4 L of water
was given every day in the warm period (May-July, August-September) and
once in two days in the cool period (March-April, October-December). Plants
started to flower on 12 April in spring and on 8 October, in autumn season.
Maximum and minimum temperatures were measured daily and shown in Fig.
1 for each growing season. Pollens were collected from fully open
flowers of male parent and transferred by hand pollination to stigmas
of those flowers in which petals just turned to yellowish green in the
first three trusses of the female parent. Pollinated flowers were isolated
with transparent paper bags to prevent foreign pollens until fruit set.
At each growing season at least 300 fruits were tagged out of simultaneously
pollinated 550-600 flowers. Fruit harvests were arranged according to
tagging day (fruit set) and were 40, 45, 50, 55, 60, 70, 80 and 90 DAA
(days after anthesis) in spring; 45, 50, 55, 60, 65, 70, 80, 90, 100 and
115 DAA in autumn season. Seeds were removed from the harvest fruit by
hand. Seeds were fermented at 25°C for 24 h by adding the same amount
of water to the slurry (1:1 v/v), then they were washed in tap water and
dried on mesh trays in the dark for two days at 25°C at which time
the seed moisture content was <10%. Seed moisture content was determined
by high temperature oven method (130°C, 1 h) (ISTA, 1996) after drying.
Changes in fruit colour by the harvest time were determined in both seasons.
Seed dry weight determination was carried out by drying four replicates
of 20 seeds per harvest at 130°C for 1 h and weighing after cooling
in a desiccator with silica gel. Mean dry mass of individual seeds was
Daily maximum (●)
and minimum (°) temperatures recorded during seed maturation
in spring and autumn growing season
Seedling Growth Test: The seedling growth test was conducted in
a glasshouse at Amanas Seeds Company, Antalya/Turkey.
Seeds during that period were stored at 5°C and 8-9% moisture content
in air tight glass jars in the dark. Seeds, four replications of 100 seeds/harvest,
were sown 2 cm deep in compost (Plantaflor-Humus Verkaufs GmBH, Germany)
in seedling modules. Seed sowings were done on 18 July 2005 and 12 February
2006 in spring and autumn seasons. Seedlings were grown in a temperature
controlled greenhouse for 25 days. Daily temperature in the greenhouse
changed between 18 and 23°C throughout the experimental period. Regular
irrigation was carried out during the emergence test. Seedlings 25 days
after sowing were counted and cleaned and above ground seedling fresh
and dry weights were determined. Seedling dry weight was determined by
drying at 80°C for 24 h and both values were expressed as mg plant-1.
Following, seedlings were removed from seedling modules, compost was searched
and germinated but non-emerged seed percentages were determined in each
Using the daily counts, the mean emergence (MET) was calculated for each
lot using the formula cited by Ellis and Roberts (1980):
MET = Σnt/Σn
n=No. of seeds newly germinated at time t
t=Days from sowing
Means of seed weight and fresh and dry seedling weight in each harvest
were compared by Duncan`s multiple range tests by using the SPSS package
program at the 5% level. Angular transformation for percentages was carried
out before analyses. Regression analyses were conducted between seedling
fresh weight and mean emergence time and its coefficient of variation
(uniformity) of seedling fresh weight and harvest times in two different
Seed dry weight gradually increased from 3.1 mg at 40 DAA to 4.2 mg at
50 DAA in spring and from 1.6 mg at 45 DAA to 4.2 mg at 80 DAA in autumn
season and thereafter seed weight remained stable. Maximum seed weight
was attained at 50 DAA in spring and at 80 DAA in autumn when fruit colour
is pink. Fruit colour changed from green to soft red during maturation
(Fig. 2). Seeds harvested between 45 and 70 DAA in spring
season were significantly (p<0.05) heavier than those of autumn.
Maximum seedling emergence in modules was attained at 60 DAA and 90 DAA,
being 89% and 91% in spring and autumn season respectively (Fig.
3). This value was significantly higher than all other harvests in
spring (p<0.05) but was significantly higher than earlier but not later
(p>0.05) harvests in autumn season. Although it is too low, seeds harvested
45 DAA and onwards started to emerge in spring but no emergence was observed
until 70 DAA in autumn season.
Maximum seedling fresh and dry weight occurred at 60 DAA as 844 mg and
68.3 mg plant-1 in spring season. Both criteria in this season
showed gradual increase by the maturity. Having reached the maximum level,
seedling fresh weight remained the same until penultimate harvest but
seedling dry weight continuously decreased (Table 1).
In autumn season, both maximum seedling fresh and dry weights were obtained
from seeds harvested at 115 DAA as 739 mg plant-1 and 54.5
mg plant-1, respectively. Both increased gradually by the maturity
starting with 80 DAA. As seeds matured the percentage of seeds germinated
but unable to emerge in the compost was reduced; this was in the lowest
at 60-70 DAA in spring and 100-110 DAA in autumn season as 2-3%. It was
much higher in less mature lots, 21%, at 45 DAA and 70 DAA, respectively
Maximum hypocotyl lengths were observed at 60 DAA in spring and 115 DAA
in autumn, as 33.1 mm and 32.6 mm, respectively. These harvests produced
significantly (p<0.05) longer hypocotyls than those of other harvests
in both growing seasons (Table 1).
Changes in seed
weight and tomato (Lycopersicon esculentum) fruit colour
(upper row for autumn, lower row for spring season) during seed
development in spring (▲) and autumn (●) season. Means
with the same letters within the same season are not significantly
different (p = 0.05). Means with asterisks are significantly different
(p = 0.05) harvests between two seasons
in relation to time of harvest and seed development in spring (▲)
and autumn (●)
grown tomato (Lycopersicon esculentum) seeds, letters are
to compare harvests in the same season, asterisks are the time of
harvests in different seasons. Means with different letters and
asterisk are significantly (p = 0.05) different
mean seedling emergence time (day) of spring (▲)
and autumn (●)
grown tomato (Lycopersicon esculentum) seeds and seedling
fresh weight (mg plant-1)
Changes in seedling
fresh weight, dry weight, hypocotyls length and germinated but unable
to emerged seed percentages in spring and autumn grown and serially
harvested tomato (Lycopersicon esculentum) seeds. The means
with different letters in the same column are significantly different
(p = 0.05)
*: No harvest was
done, DAA: Days after anthesis, SFW: Seedling fresh weight, SDW:
Seedling dry weight, GBU: Germinated but unable to emerge, HL: Hypocotyl
length, +: 40 DAA in spring was not shown since no seedling emerged
time of harvest and coefficient of variation (CV) of seedling fresh
weight in spring (▲)
and autumn (●)
grown tomato (Lycopersicon esculentum) seeds
The mean emergence time and above ground seedling fresh weight is highly
significant (p<0.05) in seed lots of both growing seasons; the slower
the emergence, the lower the mean seedling fresh weight (Fig.
As seed maturity progressed, seed lots showed less variation in seedling
size as indicated by the significant positive regression of coefficient
values between CV of seedling size and harvests in both growing seasons
(Fig. 5). However, seeds harvested during spring season
had much lower CV values
than those of autumn, which indicates that they produce more uniform
seedlings. Although spring grown seeds emerged faster and produced more
uniform seedlings than those of autumn, the lower CV value was related
to earlier emergence in seed lots of both seasons.
Findings of this study showed that temperature during seed development
affected seed dry matter accumulation, seedling emergence and growth of
hybrid tomato seeds. Seeds grown in the spring (March- July) reached to
maximum dry mass earlier than those grown in autumn (September-January).
Maximum seed quality in relation to seedling growth was obtained from
seeds harvested at 60 DAA in spring and 115 DAA in autumn season.
Following fertilization of the ovule, development of seed until harvest
involves embryo growth (Phase I, increase in size, weight and number of
cells) and accumulation of reserves (Phase II, i.e., proteins, oils, starch)
seeds do not generally have vascular connection with phloem, so that substances
(i.e., proteins, fats, starch) should move apoplastically unloading from
phloem (Naylor, 2003). When weather conditions, were lower than optimum,
specifically low temperature in our case, the rate of biomass accumulation
impaired and reduced seed weight. In autumn season due to the cool and
low temperature period and the lower rate of photosynthesis, tomato seeds
took 30 days longer to get the maximum dry weight compared to those of
spring season, although they gained equal weight finally (Fig.
Temperature during seed filling may affect seed weight and vigour in
various crops (Tashiro and Wardlaw, 1990; Jansen, 1995). Egli et al.
(1985) reported that reductions in seed weight result primarily from a
reduced seed fill duration rather than any reduction in seed growth rate.
Results of our work confirmed this conclusion that the time of the seed
filling period is completed by 50 DAA in spring season, while it extends
to 80 DAA in autumn season. Changes in temperatures not only slow down
the accumulation of dry mass but also reduce total seed quality measured
by storage longevity in rice (Ellis et al., 1993); watermelon (Demir
et al., 2004), seed harvest index in peanut (Craufurd et al.,
2002) and in normal seedlings in soyabean (Spears et al., 1997).
The basic reason of slow seed filling in protected cultivation in the
autumn growing season is that plants are subjected to gradually reducing
cooler environment as maturation progress. The minimum temperature in
autumn is lower than 10°C at 50 DAA and afterwards. However, temperature
reduced such level in only a few cases in spring (Fig. 1).
Hybrid tomato seed production was done under cover due to the easy application
of isolation methods and production control. Results indicated that autumn
growing conditions seed maturation extends over 115 DAA which is almost
doubled compared to that of spring (Table 1, Fig.
Tomato fruit colour is evaluated as an improved measure of seed quality
development (Valdes and Gray, 1998; Demir and Samit, 2001; Ramirez-Rosales
et al., 2004) along with days after anthesis (Berry and Bewley,
1991; Demir and Ellis, 1992; Liu et al., 1996). In most of the
studies seeds extracted from red tomato fruits possessed maximum quality
measured in various tests, compared to those extracted from earlier stages
of fruit maturity. More recently, Ramirez-Rosales et al. (2004)
found in high lycopene tomato cultivar that seed quality was higher at
the mature green breaker and pink breaker compared to red mature and overripe
stages. In present research, seeds produced highest emergence, seedling
fresh and dry weights obtained from firm and red fruit colour in spring
while soft and red stage in autumn (Fig. 2, 3, Table 1). This shows that
fruit development is influenced by environmental conditions and the identification
of specific physiological stages of seed development based on fruit colour
may not be universal in all growing and environmental conditions. Agreeing
with that conclusion, seeds within the late soft-red stage started to
deteriorate, shown by germination after a saturated salt solution accelerated
aging in high lycopene (Ramirez-Rosales et al., 2004) and by mean
germination time, normal seedling percentage and storage longevity in
some other cultivars (Valdes and Gray, 1998; Demir and Samit, 2001). Contrarily,
seed quality remained at maximum level in the late seed development period
in soft red fruits i.e., 90 DAA; it was postulated that this was due to
occurrence of the repair mechanism under very high seed moisture within
the fruit (Demir and Ellis, 1992). It can be postulated that this may
depend on co-interaction of cultivar and environmental conditions, which
was confirmed by our results. Seedling fresh and dry weight, hypocotyl
length and mean emergence time declined gradually having reached to a
maximum level at 60 DAA in spring season, whereas in autumn all seed quality
criteria continuously increased until 115 DAA (Table 1).
One cause of reduction in seedling growth can be the supra-optimal temperatures
in the glasshouse in late seed maturation stage (June-July, daily maximum
temperatures varies between 32 and 39°C) in spring season (Fig.
1). This is in agreement with the conclusions of various studies (Tashiro
and Wardlaw, 1990; Ellis et al., 1993; Jansen, 1995; Spears et
Maximum seed weight (mass maturity) occurred at 50 and 80 DAA in spring
and autumn season growing, respectively. However, maximum seed quality
improved after mass maturity. This changed between 10 and 35 days according
to the quality test (Fig. 2, 3, Table
1). Thus, the first part of the hypothesis of Harrington (1972) that
seed quality is maximal at the end of the seed filling phase (i.e., at
mass maturity) can be rejected on the basis of the current results. This
agrees with results of a number of different studies in tomato (Kwon and
Bradford, 1987, Demir and Ellis, 1992, Berry and Bewley, 1991; Demir and
Samit, 2001). However, the second part of the hypothesis, that seed quality
declines thereafter, is supported by the results of spring season but
not those of autumn (Table 1). That conclusion indicates
that total accuracy of both parts of the mentioned hypothesis may depend
on environmental conditions during the seed-filling phase as well as the
cultivar. Results based on hybrid cultivar in the present work unlike
open-pollinated ones in previous studies.
Recently, gradually increasing trend in the vegetable industry is to
grow transplants in modules. In tomato, along with other crops, transplants
have been used for various aims: To improve stands; to reduce seed usage;
especially of high value hybrids; to shorten the time from planting to
to get better seedlings for grafting (Cantliffe, 1994). Earliness and
uniformity are important characteristics in transplant production. Use
of well-developed and strong transplants is the prerequisite of uniform
and fast plant growth in glasshouse crop production. Results of the present
study indicate the ability of tomato seeds to produce a good transplant
is based on the environment that it was grown. Longer mean emergence time
of autumn season grown seeds was closely related to lower seedling fresh
weight, while faster emerged spring grown seeds had larger seedlings (Fig.
4). More mature seeds produced larger seedlings in both growing seasons.
This relationship between emergence time or germination time and seedling
size was also reported by Ellis and Roberts (1980) in barley, wheat, onion
and cabbage; by Gray (1984) in carrot; by Demir and Ellis (1993) in marrow
and Matthews and Khajeh Hosseini (2006) in maize. Spring growing not only
reduced mean emergence time but also increased uniformity in seedling
size. CV values of seedling fresh weight were well correlated with harvest
time. Figure 5 shows that spring growing and maturity
assures better seedling production and uniformity.
Halmer and Bewley (1984) expressed the view that crop emergence losses
are overwhelmingly due to a failure of seedlings to grow under the soil
surface rather than to germination failure. Our results indicated that
the failure of emergence is related to seed maturation level. As seeds
matured fewer seeds which germinated in the compost failed to emerge to
the surface, showing that maturation increases the seedling vigour of
the tomato seeds. The number of germinated but unable to emerged seed
percentages were inversely related to hypocotyl length. Those lots that
had longer hypocotyls also had lower percentages of germinated but non-emerged
seed (Table 1). This conclusion was in agreement with
previous findings that maturation enhances seed and seedling vigour of
tomato in optimum and adverse conditions (Kwon and Bradford, 1987; Valdes
and Gray, 1998; Demir and Samit, 2001).
In conclusion, autumn season growing delays the maximum maturation stage
of tomato seeds in turn seedling emergence and size in tomato seeds up
to 115 DAA. However, in spring maximum seedling growth and quality can
be obtained from seeds harvested at 60 DAA. This showed that the time
of occurrence of maximum seed quality, affecting seedling growth in this
work, may depend on the growing environment.
We express our gratitude to Directorate of Scientific Research Projects
of University of Ankara (project no: 20050711090) for the financial support.
1: Berry, T. and D.J. Bewley, 1991. Seeds of tomato (Lycopersicon esculentum Mill.) which develop in a fully hydrated environment in fruit switch from a developmental to a germinativa mode without a requirement for desiccation. Planta, 186: 27-34.
2: Cantliffe, D.J., 1994. Seed germination for transplants. Hortic. Technol., 8: 499-503.
Direct Link |
3: Craufurd, P.Q., P.V. Prasad and R.J. Summerfield, 2002. Dry matter production and rate of change of harvest index at high temperature in peanut. Crop Sci., 42: 146-151.
PubMed | Direct Link |
4: Delouche, J.C., 1980. Environmental effects on seed development and seed quality. Hortscience, 15: 775-780.
Direct Link |
5: Demir, I. and R.H. Ellis, 1992. Changes in seed quality during development and maturation in tomato. Seed Sci. Res., 2: 81-87.
6: Demir, I. and R.H. Ellis, 1993. Changes in potential seed longevity and seedling growth during seed development and maturation in marrow. Seed Sci. Res., 8: 247-257.
CrossRef | Direct Link |
7: Demir, I. and Y. Samit, 2001. Seed quality in relation to fruit maturation and seed dry weight during development in tomato. Seed Sci. Technol., 29: 453-462.
Direct Link |
8: Demir, I., K. Mavi and C. Oztokat, 2004. Changes in germination and potential longevity of watermelon (Citrullus lanatus) seeds during development. N.Z. J. Crop Hortic. Sci., 32: 139-145.
Direct Link |
9: Egli, D.B., R.D. Guffy and J.E. Legget, 1985. Partioning of assimilate between vegetative and reproductive growth in soybean. Agron. J., 77: 917-922.
Direct Link |
10: Ellis, R.H. and E.H. Roberts, 1980. Towards Rational Basis for Testing Seed Quality. In: Seed Production, Hebblethwaite, P.D. (Ed.). Butterworths, London, UK., pp: 605-635.
11: Ellis, R.H., T.D. Hong and M.T. Jackson, 1993. Seed production environment, time of harvest and the potential longevity of seeds of three cultivars of rice (Oryza sativa L.). Ann. Bot., 72: 583-590.
CrossRef | Direct Link |
12: Gray, D., 1984. The performance of carrot seeds in relation to their viability. Ann. Applied Biol., 104: 559-565.
13: Greven, M.M., B.A. McKenzie, J.G. Hampton, M.J. Hill, J.R. Sedcole and G.D. Hill, 2004. Factors affecting seed quality in dwarf French bean (Phaseolus vulgaris L.) before harvest maturity. Seed Sci. Technol., 32: 797-811.
Direct Link |
14: Halmer, P. and J.D. Bewley, 1984. A physiological perspective on seed vigour testing. Seed Sci. Technol., 12: 561-575.
15: Harrington, J.F., 1972. Seed Storage and Longevity. In: Seed Biology, Kozlowski, T.T. (Ed.). Vol. 3. Academic Press, New York, pp: 145-245.
16: ISTA, 1996. International seed testing association. International rules for seed testing. Seed Science Technology 24, Supplement.
17: Jansen, P.I., 1995. Seed production quality in Trifolium balansae and T. resupinatum: The effect of temperature. Seed Sci. Technol., 23: 341-352.
Direct Link |
18: Kameswara Rao, N. and M.T. Jackson, 1996. Seed production environment and storage longevity of japonica rices (Oryza sativa L.). Seed Sci. Res., 6: 17-21.
19: Kwon, O.S. and K.J. Bradford, 1987. Tomato seed development and quality as influenced by preharvest treatment with ethephon. Hortscience, 22: 588-591.
Direct Link |
20: Liu, Y., R.J. Bino, C.M. Karssen and H.W.M. Hillhorst, 1996. Water relations of GA and ABA deficient tomato mutants during seed development and their influence on germination. Physiol. Plant, 96: 425-432.
21: Matthews, S. and M. Khajeh Hosseini, 2006. Mean germination time as an indicator of emergence performance in soil of seed lots of maize (Zea mays). Seed Sci. Technol., 34: 361-369.
Direct Link |
22: Naylor, R.E.L., 2003. Seed Production. In: Encyclopedia of Applied Plant Sciences, Thomas, B., D.J. Murphy and B.G. Murray (Eds.). Elsevier Academic Press, San Diego, USA., pp: 1310-1317.
23: Passam, H.C. and E.M. Khah, 1992. Flowering, fruit set and fruit and seed development in two cultivars of aubergine (Solanum melongena L.) grown under plastic cover. Sci. Hortic., 51: 179-185.
CrossRef | Direct Link |
24: Powell, A.A., S. Matthews and M.A. Oliveira, 1984. Seed quality in grain legumes. Adv. Applied Biol., 10: 217-285.
25: Ramirez-Rosales, G., M. Bennett, M. McDonald and D. Francis, 2004. Effect of fruit development on the germination and vigor of high lycopene tomato (Lycopersicon esculentum Mill.) seeds. Seed Sci. Technol., 32: 775-783.
Direct Link |
26: Siddique, M.A. and P.B. Goodwin, 1980. Seed vigour in bean (Phaseolus vulgaris L. cv. Apollo) as influenced by temperature and water regime during development and maturation. J. Exp. Bot., 31: 313-323.
27: Spears, J.F., D.M. TeKrony and D.B. Egli, 1997. Temperature during seed filling and soybean seed germination and vigour. Seed Sci. Technol., 25: 233-244.
Direct Link |
28: Tashiro, T. and I.F. Wardlaw, 1990. The effect of high temperature at different stages of ripening on grain set, grain weight and grain dimensions in the semi-dwarf wheat banks. Ann. Bot., 65: 51-56.
Direct Link |
29: TeKrony, D.M., D.B. Egli and A.D. Philips, 1980. Effect of field weathering on the viability and vigor of soybean seed. Agron. J., 72: 749-753.
CrossRef | Direct Link |
30: Thomas, J.M.G., K.J. Boote, L.H. Allen, Jr. Gallo-Meagher and J.M. Davis, 2003. Elevated temperature and carbon dioxide effects on soybean seed composition and transcript abundance. Crop Sci., 43: 1548-1557.
Direct Link |
31: Valdes, V.M. and D. Gray, 1998. The influence of stage of fruit maturation on seed quality in tomato ( Lycopersicon lycopersicum (L.) Karsten). Seed Sci. Technol., 26: 309-318.
Direct Link |