Studies on the Vigour of Soybean Seeds : II. Varietal Differences in Seed Coat Quality and Swelling Components of Seed during Moisture Imbibition

Laboratory experiment was conducted to elucidate the physiological factor determining the association of seed size and seed coat quality with varietal differences in seed vigour, and to pursue an alternative on the mechanism of varietal differences in seed resistance to field weathering. Results of this study revealed that seed polymer change (seed volume change minus seed weight change during moisture imbibition) was the physiological factor determining the association of seed size and seed coat quality with varietal differences in seed vigour. The mechanism of varietal differences in seed resistance to field weathering, therefore, seemes to be mainly controlled by seed coat quality (seed coat-seed weight ratio and seed coat colour) through controlling the magnitude of seed polymer change during moisture absorption at postphysiological maturity, which in turn determine the degree of membrane damage in the seed