Relationship between Sugar Exudation from Imbibing Seeds and Seedling Emergence in Soybean.

Abstract

Exudation from imbibing seeds causes failure of seedling emergence under excessive soil-moisture conditions. We investigated the relationship between sugar exudation from imbibing seeds and seedling emergence under suitable and excessive soil-moisture conditions in 20 soybean cultivars. Seeds in one group(aged seeds)were exposed to 40°C and 100% relative humidity for six days and those in another group(control seeds)were not. The amount of sugars(fructose and glucose)exuded varied from 0.4mg(cv.Moyashimame)to 11.8mg(cv.Shirotae)per gram seeds in control seeds, but was larger in most of the aged seeds. The exudation was obviously great in the cultivars with yellow seed coat in both control and aged seeds. The percentage of seedling emergence in the control seeds was high irrespective of the soil moisture conditions, but that in the aged seeds was lower in particular under excessive soil-moisture conditions. A significant negative correlation between sugar exudation and the percentage of seedling emergence under excessive soil-moisture conditions suggesting that sugar exudation is highly correlated with the seedling emergence. In some cultivars with black seed coat, sugar exudation from aged seeds was low, and the percentage of seedling emergence under excessive soil-moisture conditions was higher than that in other cultivars. These cultivars considered to retain the character of seed vigor.