Abstract: The pathogenicity of Pyricularia grisea to thirty nine new rice cultivars(lines) or combinations collected from nine provinces in China were evaluated when the rice seedlings were inoculated with 92 isolates of Pyricularia grisea from seven regions in China. The pathogenicity of P. grisea isolates differ from various regions, and many cultivars (lines) or combinations are highly resistant to P. grisea and their virulent frequency are not more than 20%. The interactions between rice cultivars and blast fungi, and the utilization value of the resistant cultivars can be analyzed with pathogenicity association coefficient (PAC) and resistance association coefficient (RAC).

Key words: cultivar, pathogenicity association coefficient, Pyricularia grisea, resistance association coefficient, virulent frequency

摘要： 为探明我国稻瘟病菌对近年来育成的部分水稻新品种(系)、新组合的致病力，用来自浙江、四川、湖北、广东、云南、吉林、北京等7个省(市)的92个稻瘟病菌菌株测定了39个水稻新品种(系)或新组合的抗性，分析了稻瘟病菌的致病力和品种的抗病性。结果表明，不同稻区稻瘟病菌菌株对籼、粳、杂交稻的致病力存在明显差异。筛选出一批毒力频率在20%以下，抗性较好的籼、粳稻新品种(系)和杂交稻新组合。同时用联合致病性系数和联合抗病性系数分析了病菌和品种的群体互作以及抗瘟新品种(系)、新组合的利用价值。

关键词: 稻瘟病, 毒力频率, 联合抗病性系数, 品种, 联合致病性系数