【摘要】 １９７９年以来对４５２５９份材料的抗性鉴定表明，国际稻品种中抗性材料最多，抗谱范围广、是抗源材料的主要来源。抗谱在９０％以上的抗源有６６份。利用抗源育成推广种５个。在省内外推广１千万公顷。研究结果表明，稻瘟病菌种群变异与水稻品种抗性变异密切相关。一个地区品种抗性丧失，是由病菌优势种群及潜在致病小种的分布和出现频率所决定。潜在致病小种随品种种植面积比率的扩大而增殖，最后成为优势小种。品种自身分离菌回接致病率逐渐增长，品种抗性就逐渐下降。更多还原

【Abstract】 he pathogenicity of rice blast fungus and the resistance of 45259 rice varieties and lines to rice blast were monitored in Sichuan Province in 1979-1995The results showed that the number of rice resources resistant to rice blast from International Rice Research Institute (IRRI) was the mostThe resistance frequency of these rice varieties from IRRI was the highest,which was the main source of rice resources resistant to rice blast66 rice resources had over 90% of resistance frequencyUsing these resistant resources 5 high-yielding resistance varieties were bred,and the total planting area was 10000000 haThe resistant variation of rice varieties were colsely relative to the population variations of the fungusThe resistance loss of rice varieties in a region depended upon the distribution and frequency of a dominant population and the potential pathogenic races of the fungusThe potential pathogenic race increased with the increase of planting area of the rice variety and it become finally the dominant raceRice resistance gradually reduced with the increase of pathogenic frequency of the black infecting strains from the variety itself更多还原