Blast resistance and agronomic traits of local Indica rice and Japonica rice in Yunnan and screening of elite rice varieties

【Objective】In order to screen suitable excellent local rice varieties, analyzed the differences in blast resistance and agronomic traits between local Indica rice and Japonica rice in Yunnan. The purpose was to provide theoretical basis for resistance breeding and improved variety breeding of rice blast.【Method】In order to screen out excellent local rice varieties, 23 local Indica rice and 23 Japonica rice varieties in Yunnan were used as materials. Eight rice blast strains were used for indoor blast resistance identification and blast resistance gene derivation at seedling stage, and comprehensive evaluation was carried out combined with the results of field agronomic traits.【Result】There were 4, 5, 6 and 8 Japonica rice varieties with resistance frequency of 0.0%-25.0%, 25.1%-50.0%, 50.1% -75.0% and 75.1%-100.0%, respectively. The resistance frequency of Indica rice varieties was 0, 4, 7 and 12. After inoculation of Japonica rice and Indica rice with eight standard strains of rice blast, the blast resistance of Indica rice was generally higher than that of Japonica rice. The blast resistance gene composition of 46 rice varieties was relatively complex, of which 17 varieties could deduce the resistance gene, including 7 Japonica varieties and 10 Indica varieties. There were 23 varieties with complex resistance gene composition(there might be 6 or more resistance genes);there were 6 varieties with unknown resistance genes, all of which were Japonica rice. The frequency of Pik, Piz-t, Pib, Pi1, Pi11 and Pita-2 genes in Indica rice was higher than that in Japonica rice, and Pita-2 gene only existed in Jiqiangnuo and Tianza 58. The frequency of Pik-s, Pita, Pi3, Pi12 and Pii genes in Japonica rice was higher than that in Indica rice, and the Pi12 gene was only found in Japonica rice varieties Ribengu and Huajie. The results of agronomic traits showed that the differences of plant height, ear length, seed setting rate and 1000-grain weight among Japonica rice varieties were greatly greater than those of Indica rice varieties. In terms of yield, the difference between Indica rice varieties was less than Japonica rice. High blast resistant varieties were:Liandaogu(Japonica), Xiangnuo(Indica), Haonuozao(Indica) and Laopinzhongnuogu(Indica);high yield varieties were:Ribengu(Japonica) and Zhanjuexiang(Indica);dwarf stem varieties were:Lengshuishanyou(Japonica) and Baikenuo (Indica);multispike varieties were:Ribengu(Japonica) and Laopinzhongnuogu(Indica).【Conclusion】The number of blast resistance genes and blast resistance of Indica rice are higher than that of Japonica rice, indicating that the resistance spectrum of Indica rice is wider. The selected Japonica rice varieties Lengshui Shanyou and Ribengu can be used for breeding high quality and high yield varieties, and the Indica rice varieties Xiangnuo and Haonuozao can be used for breeding blast resistant varieties.