Effects of seed size and several factors on ultra-drying and germination of ultra-dried seeds in soybean.

摘要

Ultra-drying ( < 5.0% seed moisture content (SMC)) storage technique is a cost-effective storage method for oily seeds. To determine proper ultra-drying conditions for soyabean seeds, drying rate was compared for three silica gel to seed ratios, twoseed sizes (varieties), two kinds of container, and three seed amounts per container under 23 ?1℃. When the relative humidity (RH) was reduced at the rate of less than 0.1% a day, silica gel was renewed by 47 days. Higher silica gel to seed ratios (3:1 and 2:1) dried faster than lower ratio (1:1) until 28 days, but not after 43 days of drying. Also, the large seeded variety dried faster than the small seeded variety. Kind of container and seed amount per container did not show differences in drying of soyabean seeds. After completion of ultra-drying, percentage germination by standard germination test (SGT) was not different among silica gel to seed ratios, kinds of container, and seed amounts per container, except among seed sizes (varieties). Before SGT, soyabean seeds were premoistened using saturated CaCl2 for 48 h and NH4Cl for 24 h in desiccators. To compare germinability between ordinary-dried seeds and ultra-dried seeds, the seeds of seven soyabean varieties, which varied in size from 8.1 to 34.9 g per 100 seeds, were dried using same amount of silica gel under 23 ?1℃. After 76 days of drying, SMCs were reduced to 3.13-3.45% from 7.86-8.82%. SMC after completion of drying was not correlated with 100-seed weight (r = 0.556). Before germination tests, soyabean seeds were premoistened using saturated salt solutions. Percentage germination was higher with ultra-dried seeds than ordinary-dried seeds in SGT and higher with ordinary-dried seeds than ultra-dried seeds in accelerated aging testat the beginning of storage and after 6 months storage, but general trend of percentage germination was not observed among varieties classified by 100-seed weight. From these results, we concluded that further studies are needed to improve ultra-drying storage method for soyabean seeds.