Resistance Evaluation Of The Main Rice Cultivars And Resources To Rice Fulse Smut In Sichuan Province

Rice false smut caused by Ustilaginoidea virens (Cook) was seriously occurred in recent years and became the main disease of rice with the popularization of hybrid rice cultivar. Breeding and utilization of resistant cultivars was the most effective and economical way to control this disease and ensure the high yield of rice. In this study the resistance of 169 main rice cultivars and 126 rice germplasm resources of Sichuan province to rice false smut were evaluated by natural induced and artificial aided inoculation in 2009 and 2010. Meanwhile, the agronomic traits, restoring and maintaining characters of 121 in 126 germplasm resources were tested. The results were as follows:1 Resistance evaluation to rice false smut of 169 rice cultivars showed that the resistance of the main rice cultivars in Sichuan province was low and unstable, there were differences in resistance between varieties and years. The disease in 2010 was more serious than that in 2009. The disease spike rate range was 0.0%～36.4%, and the disease index was 0～17.0 in 2009; and in 2010, the disease spike rate range was 0.0%～22.4% and the disease index was 0～13.13.20 out of 169 cultivars were immune to moderately resistant in both two years, in which 3 cultivars were immune,3 were resistant and 16 were moderately resistant.2 Resistance evaluation of 126 rice germplasm resources to rice false smut showed that the resistance was different between varieties.63 varieties which could be used as breeding materials were immune or moderately resistant to rice false smut, in which 58 varieties were immune,4 were resistant, and lwere moderately resistant.3 The agronomic traits, restoring and maintaining characters of 121 germplasm resources were tested. Cluster analysis indicated that the main agronomic characteristics of those varieties could be divided into groupⅠand groupⅡ. GroupⅠcontained 43 varieties, and groupⅡcontained 78 varieties. The grains per spike, seeds setting rate and grain weight in groupⅡwere higher than groupⅠ. In GroupⅠ, there were 2 sub-groups,Ⅰ1 contained 26 varieties andⅠ2 contained 17 varieties; in GroupⅡ, there were 3 sub-groups,Ⅱ1 had 43 varieties,Ⅱ228 varieties andⅡ337 varieties. The test of restoring and maintaining characters showed that in 110 of 121 resources remained restoring on CMS lines,11 remained restoring and maintaining. There were 55 restoring resources hybrid with Gang 46A, and the seeds setting rate of all F1 generation was more than 80.0%. These resources can be used as parents of hybrid combinations.Above all, the resistance of main cultivars in Sichuan province was not high and unstable. Only 9 resources could be used as breeding materials because of better resistance to rice false smut, agronomic traits and restoring and maintaining characters than other resources. This study could provide guidance and theoretical basis in cultivar choosing, rice false smut controlling and resistance cultivar breeding in Sichuan Province.