ACTA PHYSIOLOGIAE PLANTARUM Vol. 28. No. 3. 2006: 000-000
Sowing seasons and drying methods during post-harvest influence the seed vigour of soybean (Glycine max (L.) Merr.) Guixiang Tang, Wenjian Song, Ling Xu, Zonglai Jin, Kasirajan Subrahmaniyan, Weijun Zhou * Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310029, China * Author for correspondence, e-mail:
[email protected]
Key words: Drying methods, electrical conductivity, peroxidase activity, seed germination, seed vigour, sowing season, soybean (Glycine max) Abstract Experiments were conducted to study the influence of sowing seasons and drying methods on the seed vigour of two spring soybean (Glycine max (L.) Merr.) cultivars. Two cultivars, ‘Huachun18’ and ‘Huachun 14’, were sown in three seasons viz., spring, summer and autumn and the harvested seeds were dried using three different methods. The results showed that soybean sown in spring had the more number of branches per plant, pods per branch and seed weight, and consequently resulted in higher seed yields than that of soybean sown in autumn or summer seasons. Seeds sown in the autumn season had the lowest values of electrical conductivity during seed imbibitions, higher peroxidase (POD) activity in germinated seedlings and lower contamination by the seed-borne fungi on the MS medium, which indirectly improved the seed vigour, which was followed by summer sown seeds. Seeds sown during the spring season resulted in poor seed vigour. In addition, the effect of drying methods on the seed vigour was also clarified. Seeds that hung for four days before threshing and then air-dried had the poorest seed vigour which was determined by germination, electrical conductivity, POD activity and seed borne fungal growth. There was no difference in seed vigour between other methods, i.e. seeds threshed directly at harvest and then air-dried on a bamboo sifter or concrete floor. These results indicated that autumn sowing soybean and the drying method in which seeds were threshed directly at harvest and then air-dried on a bamboo sifter resulted in higher seed vigour.
Introduction
Soybean (Glycine max (L.) Merr.) is a protein- and oil-rich legume. It contains approximately 40 per cent protein and 20 per cent oil along with calcium, iron, carotene, thiamine, and ascorbic acid. According to the ancient Chinese written records, soybean was cultivated as early as 2000 BC (Probst and Judd 1973). There are three types of planting in the southern multiple cropping area of China and southeast Asia, i.e. spring soybean (sowing at the beginning of April and harvesting at the end of July), summer soybean (sowing at the beginning of June and harvesting at the end of October) and autumn soybean (sowing from the end of June to the beginning of August and harvesting at the beginning of November) (Wang 2001). Spring soybean occupies major share in soybean production in southern China but the harvested seed has the poor vigour. Though seed vigour is satisfactory at harvest, the seed quality is deteriorated during the storage. In fact, ‘the re-growing in autumn’ (seeds harvested from spring soybean and re-planted in autumn) can improve the vigour of spring soybean seed, as practiced by some farmers. Soybean seed vigour of spring sowing declined faster than that of the autumn sowing after storing for 12 months un-
523
G. TANG, W. SONG, L. XU, Z. JIN, K. SUBRAHMANIYAN & W. ZHOU
der the natural conditions (Tang and Dong 1996). The seed of spring sowing soybean is prone to seed deterioration during the storage and as a result, the poor seed vigour and germinability of spring sown soy bean re tarded the rapid expansion of the soybean acreage.
Soybean seed vigour was influenced by many factors, for example, seed processing operations include receipt of raw seed, cleaning and size grading, separation of seed on a gravity separator, treatment with fungicide, bagging and storage. The thin coat of the seed is fragile and could develop cracks during handling, leading to deterioration of vigour (Wang 2001, Parde et al. 2002). The effect of sowing and harvesting dates on soybean seed vigour is important because the influences of field weathering and mechanical damage during harvest can be minimized (McDonald 1999). Adam et al. (1989) studied the effects of sowing and harvesting dates on soybean seed quality and found that late sowing (May 30) and late harvesting (October 5 or 15) enhanced seed quality whereas early planting (May 1) and early harvest (September 15) decreased seed quality. Late planting delayed maturation until environmental conditions favorable for maintaining seed quality occurred. Gowda et al. (1990) reported that seed vigour was influenced by the drying method. Sun and shade drying followed by mechanical drying with an air temperature of 40 °C were found to be optimal in terms of safe drying for better seed quality in tomato. There are no reports on the drying methods influence the soybean seed vigour.
Seed
deterioration results from seed mechanical and physiological damage (McDonald 1999, Song et al. 2004, 2005). The seed deterioration could decrease protein synthesis (Gidrol et al. 1988) and soluble oligosaccharides (Yaklich 1985), increase membrane permeability during imbibition (Seneratna et al. 1988, Ferguson et al. 1990). The soybean seed is also particularly prone to loss in seed quality due to physical damage. High temperature during the early seed development stage can cause soybean seed coat etching (Tang et al. 1998). The etched seeds were more prone to mechanical damage from abrasion, more sensitive to chilling injury, lost viability and vigour faster and exhibited twice as high of seed-borne fungi as non-etched soybean
524
seeds (Burchett and Schapaugh 1983). But there is a little literature to describe how the sowing dates and drying methods influenced the physiological and biochemical changes of the seeds. This study was undertaken to determine the effects of different sowing seasons and drying methods on the seed yield and seed vigour of spring soybean cultivars. The experiment was also to explore the physiological characteristics and seed development in spring soybean.
Materials and methods
Experiments were conducted with two spring soybean cultivars ‘Huachun 18’ and ‘Huachun 14’, during 2002 and 2003 at the experimental farm of Zhejiang University, Hangzhou (30° 10’N, 120° 12’ E). The experiment was conducted with two levels of treatments viz., three dates of sowings and three drying methods. Three different sowings were spring sowing (April 4), summer sowing (June 22) and autumn sowing (July 30). Soybean plants were harvested at full maturity, i.e. 95 % of the pods have reached their mature colour. The seed was harvested on July 16, September 8 and October 20 for spring, summer and autumn sowing respectively. The experimental plot size was 4 m x 1 m with the density of 30 plants/m2. No fertilizers were applied as the soils were highly fertile.
Three drying methods which mimic the farmer’s operations were used in this experiment. Method 1: After the harvest of soybean, seeds were threshed directly and then the seed was immediately placed on the bamboo sifter at approximately 30oC and 40 % RH for air dry. Method 2: After the harvest of soybean, seeds were threshed and the soybean seed was immediately placed on the cement floor (the traditional way to dry the seeds in China rural country) at approximately 40 ° C and 40 % RH for air dry. Method 3: The soybean plants were hung in a shaded room for 4 days, then threshed by hand and the seeds put on the bamboo sifter at approximately 30 ° C and 40 % RH for air dry. All plants were harvested and threshed by hand and the seeds were air dried on the bamboo-sifter and then stored in the desiccators under the conditions of humidity 5 % until they were tested for vigour after two months.
SOWING SEASONS AND DRYING METHODS ...
Table 1. Temperature and rainfall during 15 days after flowering of soybean in different sowing seasons * 15 days after flowering to max. pod weight stage
From max. pod weight stage to full maturity
Sowing season
Days
Average temp. (°C)
Max. temp. (°C)
Days of temp. >30 °C
Rainfall (mm)
Days with rain
Days
Average temp. (°C)
Max. temp. (°C)
Days of temp. >30 °C
Spring
33
25.8
38.3
10
496.2
13
5
31.4
38.6
4
3.0
1
Summer
36
28.7
36.1
7
154.1
11
5
23.8
33.6
0
4.2
1
Autumn
30
21.6
30.3
0
44.8
8
5
17.6
31.6
0
28.2
4
Rainfall (mm)
Days with rain
* The weather of 2 years sowing seasons was different, all data are the average of 2 years.
Before testing the vigor, the moisture content of seeds was checked and it was around 13-15 %.
The experiment was repeated in the second year and the results reported here are pooled results of the two experiments. For each experiment, various tests were employed to assess the soybean seed vigour and physiological characters. These included: Seed development and plant growth
The
soybean anthesis date (days after sowing), ripening date (days after sowing), and average and maximum seed growth rates were recorded. At maturity, the plant height, branch number, number of main stem and branch nodes, number of effective (filled) and aborted pods, 100-seed weight and seed yield were also measured. Germination test
Fifty seeds, in six replicates, were placed in sterilized sand beds in a seed germinator chamber at 25 °C for seven days in the dark. After three days, the
germination energy (GE) was recorded. The germination percentage (GP), germination index (GI) and percentage of seed decayed (PD) during germination were evaluated after seven days. GE was the percentage of germinating seeds 3 days after sowing relative to the number of seeds tested; GP was the percentage of germinating seeds 7 days after sowing relative to the number of seeds tested; PD means the percentage of decaying seeds 7 days after sowing relative to the number of seeds tested; GI = S (Gt /Tt), where Gt is the number of seeds germinated on day t and Tt is the number of days (Hampton and TeKrony 1995, Momoh et al. 2002). Electrical conductivity
Six replicates of 50 seeds in each treatment were tested. After weighing the seeds, the seeds were soaked in 150 ml double distilled water at 25 °C for 24 hours. Electrical conductivity of the solution was measured by a conductivity meter (DDS-11A type) and expressed in ms·g-1·cm-1 basis (Zhou and Leul 1998).
Table 2. Effects of sowing seasons on the soybean growth date and seed development Cultivar
Sowing season (month/day)
Anthesis (days after sowing)
Huachun 18
Spring 4/4
42
Summer 6/22
Huachun 14
Ripening (days after sowing)
Average seed growth rate (mg seed-1.d-1)
Max. seed growth rate (mg seed-1.d-1)
Time of max. seed growth rate appearance (days after anthesis)
96
5.05
14.16
35
28
76
4.25
8.78
35
Autumn 7/30
29
75
3.53
10.33
31
Spring 4/4
48
100
4.69
12.16
30
Summer 6/22
28
76
3.28
6.87
32
Autumn 7/30
30
77
3.23
11.07
26
525
G. TANG, W. SONG, L. XU, Z. JIN, K. SUBRAHMANIYAN & W. ZHOU
Table 3. Effects of sowing seasons on the soybean plant growth and seed yield per plant Cultivar
Sowing season
Plant height (cm)
Branch No.
Main stem node (No.)
Branch node (No.)
Effective pod (No.)
Aborted pod (No.)
100-seed weight (g)
Seed yield (g·plant-1)
Huachun 18
Spring
49.10 a*
4.83 8a
11.75 a
15.17 a
41.75 a
8.67 a
27.13 a
22.27 a
Summer
42.92 b
0.92 b
12.08 a
1.75 b
19.50 b
1.17 b
21.67 b
16.24 b
Autumn
30.85 c
0.67 b
10.67 b
1.17 b
14.92 b
1.42 b
17.69 c
4.14 c
Spring
45.83 a
4.08 a
10.55 a
9.58 a
42.92 a
1.17 a
23.00 a
21.58 a
Summer
43.88 b
1.83 b
10.75 a
2.00 b
34.75 a
0.25 b
16.02 b
11.05 b
Autumn
28.71 c
1.33 b
9.58 b
2.75 b
14.67 b
0.75 b
15.86 b
4.99 c
Huachun 14
* Within columns, means followed by the same letter are not significantly different at the 0.05 level of probability.
Peroxidase activity
The seeds were germinated at 25 °C for 48 hours, and the seedlings (hypocotyls and cotyledons) were used to measure peroxidase (POD) activity by the guaiacol reduction method (Zhou and Leul 1999, Zhang et al. 2005). The enzyme extracts (1 ml) were treated with 1 ml of acetate buffer (pH 5.0) and 1 ml of 0.1 % guaiacol and kept at 30 °C for 5 min. Then 1 ml of 0.08 % H2O2 solution was added; 2 min later the absorbance of extract was determined at 470 nm on a spectrophotometer (model UV-2450, Shimadzu Co., Tokyo). The POD activity was calculated as OD470 seedling-1·min-1. Seed decay and number of seed-borne fungi
distilled water. The seeds were then placed on MS (Murashige and Skoog 1962) potato-dextrose agar in 9-cm diameter culture dishes (Zhou et al. 2004). Each dish placed 10 seeds, and 50 seeds per treatment were assayed for seed-borne fungi. The samples were evaluated for fungal growth after incubation for 7 days at 25 °C. Percentage of seed decay and number of seed-borne fungi was recorded.
The
data were subjected to analysis of variance (ANOVA test) using the SPSS version 10.0 statistical package for Windows (SPSS 1999). Where the F-test showed sig nif i cant dif fer ences among means, Duncan’s multiple range tests were performed at the 0.05 level of probability to separate means.
Seeds were collected randomly from the main stem of each treatment. The seeds were sterilized to remove the microorganisms from the surface of the seed by sequentially immersing in 80 % ethanol for 20 seconds and 10 % sodium hypochlorite for 10 minutes, and then rinsing 3 times using sterilized
Results
The weather during spring, summer and autumn sowing growth seasons was obviously different. It was mild and rainy in spring sowing season with the
Table 4. Effects of sowing seasons on soybean seed germination and seed decay as determined by germination test
Cultivar Huachun 18
Huachun 14
* Within
526
Sowing season
Germination energy (%) c*
Germination (%)
Seed decay (%)
Germination index
70.67 b
7.00 a
17.99 b
Spring
41.00
Summer
24.67 b
85.67 ab
8.00 a
16.72 b
Autumn
84.00 a
95.33 a
1.06 b
19.64 a
Spring
57.67 b
87.33 b
6.33 a
20.19 b
Summer
61.67 b
93.67 a
4.67 ab
21.73 b
Autumn
92.00 a
97.00 a
2.00 b
24.00 a
columns, means followed by the same letter are not significantly different at the 0.05 level of probability.
SOWING SEASONS AND DRYING METHODS ...
Table 5. Peroxidase (POD) activity and number of seed-borne fungi in soybean seeds sowed in the spring, summer and autumn seasons.
Table 7. Peroxidase (POD) activity and number of seed-borne fungi in soybean seeds under various drying methods Cultivar
Drying method 1)
POD activity (OD470 seedling -1·min-1)
Number of seed-borne fungi (numbers per 100 seeds)
1.00 b 5.00 a 0.00 c
Huachun 18
Method 1 Method 2 Method 3
31.22 a * 29.22 a 25.27 b
1.00 b 2.00 b 5.00 a
2.00 b 3.50 a 1.00 b
Huachun 14
Method 1 Method 2 Method 3
36.50 a 36.32 a 29.48 b
2.00 b 3.00 b 7.00 a
Cultivar
Sowing season
POD activity (OD470 seedling -1·min-1)
Number of seed-borne fungi (numbers per 100 seeds)
Huachun 18
Spring Summer Autumn
16.71 b * 23.77 a 26.78 a
Huachun 14
Spring Summer Autumn
18.92 b 22.71 a 26.35 a
*
Within columns, means followed by the same letter are not significantly different at the 0.05 level of probability.
average temperature of 28.7 °C and the precipitation was 501 mm, whereas the average temperature of 19.6 °C and the rainfall of 73 mm were observed in autumn sowing season (data not shown). The temperature during soybean seed development, which has been related to the soybean seed vigour was especially different (Table 1). During the period of 15 days after anthesis to maximum pod weight stage, the average and maximum temperatures, the days of temperature >30 °C and the precipitation of autumn sowing season were lower than those of spring sowing season. During maximum pod weight stage to full maturity, the average temperature in spring sowing season reached 31.4 °C which was 13.8 °C higher than that of autumn sowing. The maximum temperature in spring sowing season was 38.6 °C whereas it was only 31.6 °C in autumn sowing. The precipitation showed no ob-
1)
After the harvest of soybean, seeds were threshed and then immediately placed on the bamboo sifter (method 1) or cement floor (method 2), or the soybean plants were hung for 4 days before threshing and then air-dried (method 3). * Within columns, means followed by the same letter are not significantly different at the 0.05 level of probability.
vious difference between the seasons. It was concluded that the soybean seed formation in spring sowing season was affected by high temperature and rainy conditions, whereas the weather at seed formation in autumn sowing was cooler and drier. The weather in summer sowing season was milder which was between those of spring and autumn sowing seasons.
The soybean growth date and seed development of two cultivars in three sowing seasons are presented in Table 2. It shows that the anthesis date (days after sowing) of cultivars Huachun 18 and Huachun 14 in spring sowing was prolonged by 13 and 18 days respectively, compared to autumn sowing. The average and the maximum of the seed growth rates of
Table 6. Effects of drying methods on the soybean germination and seed decay as determined by germination test Cultivar Huachun 18
Huachun 14
Drying method 1)
Germination energy (%) a*
Germination (%)
Seed decay (%)
Germination index
90.67 a
3.00 b
53.58 a
Method 1
73.50
Method 2
74.00 a
92.50 a
2.50 b
53.25 a
Method 3
55.00 b
91.00 a
4.50 a
43.00 b
Method 1
80.83 a
91.50 a
2.17 b
55.92 a
Method 2
71.50 b
87.67 a
3.83 b
46.25 b
Method 3
57.33 c
78.67 b
8.50 a
38.00 c
1)
After the harvest of soybean, seeds were threshed and then immediately placed on the bamboo sifter (method 1) or cement floor (method 2), or the soybean plants were hung for 4 days before threshing and then air-dried (method 3). * Within columns, means followed by the same letter are not significantly different at the 0.05 level of probability.
527
G. TANG, W. SONG, L. XU, Z. JIN, K. SUBRAHMANIYAN & W. ZHOU
Fig. 1. Electrical conductivity of soybean seeds (cultivars Huachun 18 (left) and Huachun14 (right)) during imbibition of seeds sown in the spring, summer and autumn seasons. Bars indicate SE.
Fig. 2. Electrical conductivity of soybean seeds (cultivars Huachun 18 (left) and Huachun 14 (right)) during imbibition under various drying methods. After the harvest of soybean, seeds were threshed and then immediately placed on the bamboo sifter (method 1) or cement floor (method 2), or the soybean plants were hung for 4 days before threshing and then air-dried (method 3). Bars indicate SE.
both cultivars in spring sowing season were higher than that in autumn sowing. This was attributed to the high temperature during seed development in spring sowing. In terms of the soybean growth date and seed development, the summer sowing soybean was similar to that of autumn sowing. Furthermore, soybean sown in spring had the more number of branches per plant, more pods per branch and higher seed weight, and consequently resulted in higher seed yields than that of the seeds sown in autumn or summer seasons in both genotypes (Table 3).
There was significant difference in soybean seed germination and percentage of seed decay among spring, summer and autumn sowing seasons (Table 4). Generally, early sowing produced lower quality seeds compared to the late sowing. The highest germination energy, germination percentage and germination index were observed from autumn sowing in both cultivars, which were significantly higher than that of spring sowing. Soybean seeds from autumn sowing season had a lower percentage of seed decay than that of the seeds in spring sowing. The seed vigour of summer sowing season was between that of spring and autumn sowing seasons. Similarly, seeds from the autumn sowing demonstrated a greater reduction in electrical conductivity during
528
imbibitions compared to the spring and summer sowings in both cultivars (Fig. 1). Moreover, seeds from the autumn sowing season exhibited the higher POD activity and lower number of seed-borne fungi than that in the seeds from spring and summer sowings (Table 5). These results show that spring sowing of soybean seeds resulted in reduced seed vigour as assessed by various tests of seed quality.
The greatest seed vigour and lowest seed decay, as monitored by the germination test, were obtained from the drying method 1 and method 2 (seeds were threshed and then immediately placed on the bamboo sifter or cement floor, respectively) in both soybean cultivars tested (Table 6). The seed conductivity during imbibitions of both genotypes indicated that seeds from the drying method 3 (soybean plants were hung for 4 days before threshing and then air-dried) exhibited a slight increase in conductivity compared to the other drying methods (Fig. 2). Consequently, seeds from the drying method 3 showed the lowest activity of POD and the highest level of seed-borne fungi (Table 7). These results clearly revealed that seeds with the poorest vigour were obtained when the seeds were dried by method 3.
SOWING SEASONS AND DRYING METHODS ...
Discussion
This study has examined the effect of spring, summer and autumn sowings on the soybean seed vigour and physiological characteristics using two different spring cultivars. We found that autumn sown seeds resulted in higher seed vigour whereas spring sown seeds had lower seed vigour. This was accordant with the other studies using standard germination test and conductivity measurement as the criterion for seed vigour (Feaster 1942, Green et al. 1965, Adam et al. 1989). The poor seed quality from the spring sowing is probably attributed to the environmental conditions during the seed maturation. The superior quality of seeds produced in the autumn sowing was perhaps due to the cool, dry conditions of the autumn season (Horlings et al. 1991). Early sowing generally results in early maturing of plants where seeds develop in hotter and more humid conditions (TeKrony et al. 1987), thereby reducing seed quality. Temperature of 33 or 38¡æ during seed development reduced seed germination and seed vigour (Spears et al. 1997). The effect of temperature was evident during seed development but not much after reaching physiological maturity. Warm and moist conditions may increase infection of seeds by fungi thereby reducing quality (TeKrony et al. 1987). The present experiments obtained similar results in the amount of seed-borne fungi for two soybean cultivars. The infection of seed-borne fungi may lead to the decrease of seed vigour in spring sowing.
The viability of spring soybean seed is difficult to maintain (Tang and Dong 1996). Free radical-induced lipid peroxidation is considered to be one of the major causes of seed deterioration (Leul and Zhou 1999), and spring sown seeds lost most of antioxidant enzyme activity in this work thereby reducing the peroxide scavenging capacity. The loss of enzyme activity might partially explain why the soybean seed sown in spring season is liable to deteriorate and could not maintain viability longer.
Soybean seed is also short-lived and remains susceptible to mechanical damage, for instance germination declined by 10 % when dropped from a height of only 1 m (Shrivastava and Ojha 1986). This study showed that soybean seed dried by method 3, i.e. soybean plants hung for 4 days in
shade and then threshed and air-dried, lost more vigour than the other two methods of drying. Drying method 3 may however lead to seed prone to seed-borne fungal growth, as indicated in this work. This might be the reason leading to the reduction of seed vigour.
In conclusion, sowing soybean in spring is quite popular but the poor seed vigour has restricted its production. Sowing soybean in autumn can enhance the seed vigour whereas the seed yield is still limited. Additional studies are needed to determine the characteristics such as seed coat structure and the ways to improve the seed yield of autumn sown soybean. Acknowledgements
The project was supported by grants from Zhejiang University and Zhejiang Provincial Science and Technology Department, China. The authors thank C. Morgan of John Innes Centre, UK for critical reading of the manuscript. References Adam N. M., McDonald M. B., Henderlong P.R. 1989. The influence of seed position, planting and harvesting dates on soy bean seed quality. Seed Sci. Technol., 17: 143-152. Burchett C. A., Schapaugh W. T. 1983. Soybean seed coat etching: influence on seed quality. Agronomy Abstracts, 118. Feaster C. B. 1942. The influence of planting date on yield and other characters of soybeans growing in southeast Missouri. Agronomy J., 41: 57-62. Ferguson J. M., TeKrony D. M., Egli D. B. 1990. Changes during early soybean seed and axis deterioration: 1. Seed quality and mitochondrial respiration. Crop Sci., 30: 175-179. Gidrol X., Noubhani A., Mocquot B., Fournier A., Pradet A. 1988. Effect of accelerated aging on protein synthesis in two legume seeds. Plant Physiol. Biochem., 26: 281-288. Gowda S. T., Talukdar K. C., Ramaiah H. 1990. Effects of drying methods on seed quality in Tomato (Lycopersicon lycopersicum). Seed Res., 18: 126-129. Green D. E., Pinnel E. L., Cavanah L. E., Williams L. F. 1965. Effect of planting date and maturity date on soybean seed quality. Agronomy J., 57: 165-168.
529
G. TANG, W. SONG, L. XU, Z. JIN, K. SUBRAHMANIYAN & W. ZHOU
Hampton J.G., TeKrony D.M. 1995. Handbook of Vigor Test Methods. The International Seed Testing Association. Zurich. Horlings G. P., Gamble E. E., Shanmugasundaram S. 1991. The influence of seed size and seed coat characteristics on seed quality of soybean in the tropics: field weathering. Seed Sci. Technol., 19: 665-685. Leul M., Zhou W. J. 1999. Alleviation of waterlogging damage in winter rape by uniconazole application: Effects on enzyme activity, lipid peroxidation and membrane integrity. J. Plant Growth Regul., 18: 9-14. Momoh E. J. J., Zhou W. J., Kristiansson B. 2002. Variation in the development of secondary dormancy in oilseed rape genotypes under conditions of stress. Weed Res., 42: 446-455. Murashige T., Skoog F. 1962. A revised medium for rapid growth and bioassay with tobacco tissue cultures. Physiol. Plant., 15: 473-497 McDonald M. B. 1999. Seed deterioration: physiology, repair and assessment. Seed Sci. Technol., 27: 177-237. Parde R. S., Kausal R. T., Jayas D. S., White D. G. 2002. Mechanical damage to soybean seed during processing. J. Stored Products Res., 38: 385-394. Probst A. H., Judd R. W. 1973. Origin, US history and development and world distribution. In: Caldwell, B. E. (Ed.), Soybeans: Improvement, Production, and Uses. The American Society of Agronomy Inc., Madison, WC, pp. 1-5. Seneratna T., Gusse J. F., Mckersie B. D. 1988. Age-induced changes in cellular membranes of imbibed soybean axes. Physiol. Plant., 73: 85-91. Shrivastava P. K., Ojha T. P. 1986. Features of material handling in case of soybean. Proceedings of the National Seminar on Soybean Processing and Utilization in India. CIAE. Bhopal, MP, November 22-23. Song W. J., Lou J., Hu J., Cao D. D., Zhou W. J. 2004. The influence of temperature and moisture content on the longevity of bio-coated rapeseed (Brassica napus L.) during storage. J. Zhejiang Univ. (Agric. & Life Sci.), 30: 363-368. Song W. J., Zhou W. J., Jin Z. L., Cao D. D., Joel D. M., Takeuchi Y., Yoneyama K. 2005. Germination response of Orobanche seeds subjected to conditioning
temperature, water potential and growth regulator treatments. Weed Res., 45: 467-476. Spears J. F., TeKrony D. M., Egli D. B. 1997. Temperature during seed filling and soybean seed germination and vigor. Seed Sci. Technol., 25: 233-244. SPSS. 1999. SPSS for Windows, version 10.0. SPSS Inc, Chicago, 233S, Wacker Drive, Chicago, Illinois, USA. TeKrony D. M., Egli D. B., White G. M. 1987. Seed production and technology. In: Wilcox, J.R. (Ed.), Soybeans: Improvement production, and uses. 2nd ed. Agronomy Monograph 16 ASA-CSSA-SSSA, Madison, WI, pp. 295-353. Tang G. X., Dong M. Y. 1996. The vigor changes of different planting spring soybean seed after storing. J. Zhejiang Agric. Univ., 22: 614-618. Tang G. X., Wang Z. Q., Dong M. Y., Chen C. T. 1998. Effects of plantings in spring and autumn on the vigor of spring soybean seed in the southern region. Acta Agrono. Sinica, 24: 243-247. Wang Z. Q. 2001. Soybean cultivation. In: Zhang, G.P., Zhou, W.J. (Eds.), Cultivation of Crops. Zhejiang University Press, Hangzhou, pp. 200-240. Yaklich R. W. 1985. Effect of aging on soluble oligosaccharide content in soybean seeds. Crop Sci., 25: 701-704. Zhang Z. J., Mao B. Z., Li H. Z., Zhou W. J., Takeuchi Y., Yoneyama K. 2005. Effect of salinity on physiological characteristics, yield and quality of microtubers in vitro in potato. Acta Physiol. Plant., 27: 481-489. Zhou W. J., Leul M. 1998. Uniconazole-induced alleviation of freezing injury in relation to change in hormonal balance, enzyme activities and lipid peroxidation in winter rape. Plant Growth Regul., 26: 41-47. Zhou W. J., Leul, M. 1999. Uniconazole-induced tolerance of rape plant to heat stress in relation to changes in hormonal levels, enzyme activities and lipid peroxidation. Plant Growth Regul., 27: 99-104. Zhou W. J., Yoneyama K., Takeuchi Y., Iso S., Rungmekarat S., Chae S. H., Sato D., Joel D. M. 2004. In vitro infection of host roots by differentiated calli of the parasitic plant Orobanche. J. Exp. Bot., 55: 899-907.
Received October 27, 2004; accepted January 19, 2006 edited by J. Kêpczyñski
530
