Abstract: A sample of 96 soybean cultivars were evaluated for their diseased rate (I), diseased rank (S), latent period (LP) and rate of disease development (R) in order to study the quantitative resistance to SMV in soybeans. The results showed that the performances of the above four resistance components were significantly different among cultivars and that some of the cultivars such as Lishuizhongzihuangdou, Peixiantianedan, Youbian30 could be infected by four SMV strains, Sa, SC8, N1 and N3, but their I, S, and R were lower and LP longer than most of the cultivars. These results demonstrated the existence of quantitative resistance to SMV besides qualitative resistance in soybeans. Some soybean cultivars such as Lishuizhongzihuangdou and AGS19, which previously were identified as resistant to SMV infection, were in fact susceptible, but resistant to expansion. The resistance to SMV in Pixianchadou and Huaiyinqiuheidou might be either qualitative or quantitative. The present study also indicated that the resistance spectrum and durability of cultivars with quantitative resistance might be wider and longer than those with qualitative resistance.

Key words: Soybean (Glycine max L.), Soybean mosaic virus, Quantitative resistance, Germplasm evaluation