Abstract:Rice blast is one of critical factors that reduce rice production. Breeding and cultivation of cultivars with durable blast resistance and broad-spectrum has been proved to be the most promising strategy to solve this problem. To improve blast resistance of Jinggeng1, the introgression and pyramiding of blast resistance genes Pi9, Pigm, and pi21 were conducted through crossing, backcrossing, multiple crossing and self-crossing in combination with marker-assisted selection (MAS) and selection against agronomic traits. The results showed that resistance frequency of the resistance-improved line with Pi9 reached 100%, and that of the resistance-improved lines with Pigm averagely reached 90%. Both of them were extremely significantly higher than that of recurrent parent Jinggeng1. And the agronomic traits of these lines were quite similar with that of Jinggeng1. The resistance-improved line with pi21 had no significant difference of resistance frequency with Jinggeng1 but had significantly decreased grain yield per plant as compared with Jinggeng1. Comparing with Jingjing1, the resistance frequency of pyramiding line of Pi9 and pi21 was significantly improved, reaching 93.33% with significant decrease in grain yield per plant. The results indicated that introgressions of Pi9 and Pigm can greatly improve blast resistance and have less negative effects on agronomic traits, thus showing great potential application of the two genes in rice breeding for blast resistance. Due to pi21‘s relative poor resistance and narrow resistance-spectrum as well as possible negative effects on yield, it isn’t recommended to separately use it for improvement of blast resistance. Combination of pi21 with other strong resistance genes could be proper for improvement of blast resistance by multiple backcross and selfing to break its unfavorable linkage drag with yield trait.