Studies On Roles Of β-amylase On Seed Development And Biochemical Basis Of Pre-harvesting Sprouting In Spring Soybean

The objectives of this study were to learn developmental characteristics of seven different varieties, determine roles of soybean P -amylase on seed development and biochemical basis of precocious germination in soybeans.The results show that water content and fresh weight of spring soybeans increased rapidly after beginning seed stage and decreased slowly after beginning maturity. Dry weight of seeds changed in a pattern of "S" curve. The germination index of soybean seed increased rapidly from full seed stage to beginning maturity stage, so did the germination percentage. Germination ability of seeds was correlated with seed storage composition accumulation and the correlation between germination ability and dry weight of seeds is positively significant.Soybean β-amylase activity increased with seed development and the accumulation of dry composition and decreased with seed germination and composition consuming. Soybean β-amylase activity also decreased after precocious germination and the correlation between soybean 3 -amylase activity and germination percentage and index is positive in varieties tolerant to precocious germination and negative in the susceptible ones.The four varieties susceptible to precocious germination can be grouped into two categories: one included 95-1 and 9701, the other included Huachun18 and Shorter Soybean. Precocious germination of the former and the latter varieties occurred during full seed stage and beginning maturity stage respectively. Seeds of the former had not start dehydration yet and the germination percentage of the fresh seeds reached more than 60%. On the contrast, the latter ones were dehydrating and the germination percentage of the fresh seeds reached more than 80%.After beginning maturity stage, the peroxidase activity of varieties tolerant to precocious germination was lower than those susceptible to. Because peroxidase was one of the key enzymes effecting on the start of seed germination, the precocious germination may correlate with the higher peroxidase activity.If soybean β-amylase can be regarded as a kind of storage protein, precocious germination can lead to a decrease of seed storage protein, then the decrease of yield and quality. The study also suggested that precocious germination caused the decrease of germination percentage of harvesting seeds later.