Relationship between sugar exudation from imbibing seeds and seedling emergence in soybean

Exudation from imbibing seeds causes failure of seedling emergence under ex cessive soil-moisture conditions. We investigated the relationship between sugar exudation from imbibing seeds and seedling emergence under suitable a nd excessive soil-moisture conditions in 20 soybean cultivars. Seeds in one group (aged seeds) were exposed to 40 degreesC and 100% relative humidity for six days and those in another group (control seeds) were not. The amoun t of sugars (fructose and glucose) exuded varied from 0.4 mg (cv. Moyashima me) to 11.8 mg (cv, Shirotae) per gram seeds in control seeds, but was larg er in most of the aged seeds. The exudation was obviously great in the cult ivars with yellow seed coat in both control and aged seeds. The percentage of seedling emergence in the control seeds was high irrespective of the soi l moisture conditions, but that in the aged seeds was lower in particular u nder excessive soil-moisture conditions. A significant negative correlation between sugar exudation and the percentage of seedling emergence under exc essive soil-moisture conditions suggesting that sugar exudation is highly c orrelated with the seedling emergence. In some cultivars with black seed co at, 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 see d vigor.