Two hundred wild soybean lines were used to investigate water imbibition of seeds and its relationships with seed coat structure. Those structures were observed under the light microscope and the surface structure and cell arrangement was done under the scanning electron microscope. One hundred and ninety seven out of 200 wild soybean genotypes (98.5%) had hard seed and only three wild soybean genotypes, YWS16, YWS67, and YWS136 collected in Korea showed the permeability to water. Those three permeable lines showed less endocarp deposits whereas the hard seed lines did thick deposits. Larger cracks were found in permeable seed lines, however, no crack or tightly cracks were found in hard seed lines. The structure in the cell arrangement of palisade layer was looser than hard seed lines. The less compact cell arrangement in palisade cell layer and lower endocarp deposits with large cracks were considered as main factors affecting the permeability of wild soybean seeds.

Genetic diversity plays a great role in the survival and adaptability of a species under changable environment. Korea is known as original region of cultivated soybean species with high genetic diversity of wild and cultivated soybean lines. We have collected many semi-wild soybean lines, however, the information about the genetic diversity of these lines is limited. And also the phylogenetic relationship and genetic distance among the semi-wild, typical wild types (Glycine soja Sied. & Zucc.), and cultivated soybean(Glycine max (L.) Merr.) have been controversial. This study was carried out to analyze the diversity of the three groups, and to verify their genetic variation and relationships among them. The diversity indexes of typical wild, semi-wild, and cultivated soybean accessions were 0.854, 0.677, and 0.528, respectively. According to the cluster analysis for the genetic relationships, 58 accessions were defined into three genetic groups. Cluster I consisted of 20 cultivated soybean accessions and three semi-wild soybean lines. Cluster II contained 13 semi-wild soybean lines and one typical wild soybean line. Cluster II included 21 typical wild soybean lines and one semi-wild soybean line. Genetic distance between cultivated and semi-wild soybean, typical wild and semi-wild, and cultivated and typical wild were 0.525 0.761 and 0.810, respectively. The relationship between semi-wild soybean was much closer to the cultivated soybean the to the wild soybean