水稻抗稻瘟病育种要从真抗性和田间抗性两方面进行。利用真抗性时,必须正确地推断亲本的真抗性基因型,明确其与已知的真抗性基因之异同,有效地选定亲本。根据水稻对接种多种稻瘟病菌小种菌系的反应型推断水稻品种的真抗性基因型的方法,对于已导入了已知的真抗性基因的品种、系统是极其有效的,但不适于引进材料尤其是具有未知真抗性基因的材料。因此,这里提出利用回交及其对小种的反应推断真抗性基因型的方法。基本的想法是首先选择用早晚播法等被推断具有真抗性的引进材料(A),把不具有抗性基因的鉴定用品种(B)与A杂交, Rice blast resistance breeding from both true resistance and field resistance. The use of true resistance, we must correctly infer the true resistance of the parent genotype, clear its known and true resistance gene similarities and differences, effectively selected parents. The method of deducing the true resistance genotypes of rice cultivars based on the response of rice to inoculation of a variety of Magnaporthe oryzae germ plasmids is extremely effective but not suitable for the cultivars into which the known true resistance gene has been introduced In the introduction of materials, especially those with unknown true resistance genes. Thus, a method of deducing true resistance genotypes using backcrossing and its reaction to races is proposed here. The basic idea is to first select the introduced material (A) which has been deduced to have true resistance by morning and evening sowing, etc., and the identification variety (B) which does not have a resistance gene is crossed with A,