| Rice sheath blight is a kind of common fungal disease caused by Rhizoctonia solani.It is known as one of the three major diseases of rice.Studies have shown that this disease can reduce the yield of rice by 10% ～ 30%,or more than 50% if the disease is serious.In recent years,with the application and promotion of varieties with high yield,short stem,tillering and fertilizer tolerance,as well as the application of high-fertilizer dense planting and cultivation technology,the occurrence area of this disease continues to expand,the harm is increasingly serious,has risen to the first major disease in rice areas in southern China,seriously threatening rice production.Rice is one of the main food crops in guizhou,to clear the rice sheath blight in guizhou’s present situation,this study for the nine districts the rice-growing area of sheath blight hazard investigation and sample collection,by conducting the pathogen isolation,identification and determination of pathogenicity,and evaluation of rice sheath blight resistance identification of resource materials research,obtained has the following findings:1.Through the survey found in Guizhou rice sheath blight to harm occurs frequently,the incidence of rice sheath blight in the field are all around in more than 4 a,the average was 47.1%,and the incidence of tongren,guiyang,anshun,zunyi four incidence is higher,the average incidence was52%,51%,50% and 48% respectively,more than the entire province average level,In addition,except zunyi,the incidence rate was half or above.There were differences in incidence among fields,which were related to geographical altitude,latitude and longitude.2.Rhizoctonia Solani was the main pathogen of rice sheath blight in Guizhou Province,accounting for 91.87% of the total samples.A small proportion of pathogens were Rhizoctonia oryzae-sativae,accounting for 8.13%.3.The ag1-IA fusion group was the dominant population of Rizoctonia Solani in Guizhou province,accounting for 89.12% of the total number of r.solanum,and 10.88% belonged to other fusion groups.Strains from different regions were also dominated by Rhizoctonia Solani4.There were differences in virulence among strains of rice bacterial wilt in Guizhou Province,with the dominant strains with strong virulence accounting for 80.91% of the total number of samples.The dominant strains with strong virulence accounted for 48.85% of the total number of samples,and 19.09% strains with moderate or lower virulence.In addition,from different parts of the irulence stronger or more strains in the area of analysis,the guizhou province nine areas the proportion of more than 60%,so the threat of rice sheath blight in rice production in guizhou is larger,the production should pay attention to the layout of the rice varieties more,at the same time also suggests that guizhou rice sheath blight disease force has relationship with geographic origin,but there is no absolute correlation.5.In order to screen the rice resource materials that can be used for the breeding of rice sheath blight resistant varieties,178 rice materials were preliminarily determined and evaluated for their resistance to sheath blight.81 rice materials were found to have certain resistance,accounting for45.50%.Among them,71 varieties were moderately resistant,accounting for 39.89%.10 resistant materials,accounting for 5.62%;No high resistance or immune material was found. |
