Abstract
Many studies on soybean have been carried out to raise the productivity, oil and protein content and to breed the cultivars resistant to many diseases (SAITO et al., 1980; OJIMA et al., 1987). However, few studies have been conducted on green-soybean in which the eating quality, i.e. flavour, sugar content and hardness may be the important characters (KOUDA, 1934). In the current experirnent, the water absorption characteristics of ripened seeds were examined using 35 green soybean cultivars and 86 ordinary soybean cultivars. As the water absorption characteristics, the followings were measured, i.e. the rate of water absorption per dry weight of seed coat and cotyledon, the rate of water absorption per seed volume, the rate of embraced water in seeds and regression coefficients of water absorption to time during a period in which the water absorption progresses linearly. The discriminant analysis for these five water absorption characteristics showed that the green soybean seeds had high values of the rate of water absorption per cotyledon dry weight, and the ordinary soybean seeds had high values of regression coefficients (Fig. 2). These results indicate that even the ripened seed of green soybean retain the characteristics relating with the eating quality, i.e. to absorb a large amount of water due to a high content of "internal forces" (SHULL, 1914) which is attributed to content of sugars and aminoacids and due to the soft texture of soybean seeds (KAWAKAMI, 1949; OKAMURA, 1968). The high water absorption of green soybean seeds may also be ascribed to their soft tissue architecture of cotyledon.
