Abstract:For studying pathogenicity of Magnaporthe grisea derive from indica and japonica rice varieties (indica and japonica fungi), 230 indica rice varieties and 183 japonica rice varieties were inoculated by using 10 isolates, which represented main races derived from six indica rice and four japonica rice varieties. The results showed that indica fungi mainly infect indica rice with the percents of middle and serious disease of 25.22% and 12.61%, and they are obviously higher than those of japonica rice; japonica fungi mainly infect japonica rice with the percent of serious disease of 40.44%, and it is obviously higher than that of indica rice. There is 69.57% in indica rice varieties that show less disease after inoculating by indica fungi than by japonica fungi, and the percents of light, middle and serious disease in indica rice after inoculating by indica fungi are obviously higher than those by japonica fungi. Japonica rice varieties have a big percent that show worse disease after inoculating by japonica fungi than that by indica fungi, and the percent of japonica rice varieties with light disease after inoculating by indica fungi is higher, while with the serious disease after inoculating by japonica fungi.