Abstract
Roles of seed coat on interspecific differences in germination behaviors were surveyed in seeds of a series of species of genus Dioscorea. Each species has specific distribution area from southern warm places to northern cold places in East Asia. Even in species of the southern warm places, their deeply dormant seeds were able to fully germinate if their seed coats were removed. Lanolin coating instead of removed seed coat had no effect on germination. No differences in density of intercellular spaces of seed coat among species were observed by SEM. The function of seed coat is likely to not be physical barrier for water and gases. Observations by a light microscope suggest that some cells in the four cell layers of seed coat undergo certain physiological process. Seed coat may cause interspecific differences of germination behaviors in relation to north-south distribution of species.
