STRUCTURE AND CHEMICAL COMPOSITION OF WILD SOYBEAN SEED COAT RELATED TO ITS PERMEABILITY

Abstract

Four wild and two cultivated soybeans were examined for the water imbibition and relationships with seed coat structure, histochemical and epicatechin content using light, fluorescence, electron microscope, and HPLC technique. Cultivated cultivars, Pungsan and Chungja showed the highest water permeability, while the wild soybean lines, YWS16 and YWS136 showed moderate, and YWS1420 and YWS1459 did not absorb water for 24 hours. Seed coat surface of Pungsan, Chungja, YWS16, and YWS16 showed free deposits with rarely thin deposits exposing a cutin layer, while those of YWS1420 and YWS1459 were thick, rarely exposing the cuticle. In permeable genotypes, several cracks were found and the size of the cracks ranged from 1 to 2 µm. However, in impermeable genotypes, the cracks were not found in all seeds except for the tiny cracks (0.1 - 0.2 µm) in YWS1459. The free deposit with lager cuticle cracks on the seed coat surface seems to be related to permeability of wild soybean seed coat.