Responses of soybeans to water stress during germination Ⅰ. Variation among Soybean Genotypes in Germination and Seedling Growth under Water Stress

Laboratory experiments were conducted to ascertain responses of soybeans to water stress during germination. Germination of 101 genotypes was measured under water stress at 25℃. Nine genotypes among the 101 tested were consistently ranked ‘high’ for germination at -3, -6, -12 and -15 bars soil moisture tension. Most genotypes germinated at levels up to -12 bars, but failed to germinate at -15 bars. The critical soil moisture for soybean germination was between -12 and -15 bars. Both genotype and moisture × genotype interactions were highly significant sources of variation for germination and seedling growth. The soil moisture level × genotype interactions were largely due to differences in magnitude of responses rather than to direction of responses to the decreasing soil moisture. The specific effect of soil moisture treatment on germination and seedling growth was confounded by initial differences in seed quality.