Evaluation Of Rice Cultivar Blast Resistance And Green Control Technology Of Main Diseases In Taojiang,hunan

Rice is an important food crop in China and even in the world.Rice yield and quality are seriously affected by the damage of rice diseases and insect pests.This research mainly evaluated the blast resistance of the mainly planted rice varieties in Taojiang county of Hunan Province,with the aim to providing an important basis for the distribution of blast resistance of rice varieties in the county;At the same time,we also studied the green comprehensive prevention and control technology for the main rice diseases in the county,in order to obtain the green prevention and control technology for rice diseases in this county,thus to reduce the environmental and ecological harm,caused by pesticide abuse,and to ensure the safe production of rice.In 2018,ninety Magnaporthe oryzae isolates were obtained by using single spore isolation from the diseased rice samples of different varieties collected in Taojiang.Using seven pairs of SSR primers,cluster analysis was performed on ninety single spore isolated isolates.Results showed that these isolates could be divided into eight lineages when the similar level was set as 0.7.LineagesⅣ-Ⅷwere dominant genealogies,accounting for18.89%,17.78%and 17.78%of the total number of isolates,whereas lineagesⅣ-Ⅷaccounts for 4.44%-13.33%of the total number of isolates.These results indicated that the genetic structure of the M.oryzae isolates in Taojiang was more complicated.Using in vitro inoculation method,fifty-three M.oryzae isolates were inoculated on 20near isogenic lines(NILs)of rice varieties with single resistance gene.Results showed that there was no weak pathogenic strain,and the pathogenicity rate of the fifty-three tested isolates on 20 NILs ranged from 39.13%to 91.30%,with the mean pathogenic rate of63.49%.The fifty-three isolates were virulent against the resistance genotype Pi-z~5、Pi-z~t、Pi-ta、Pi-t、Pi-sh、Pi-1、Pi-5、Pi-19、Pi-11,whereas exhibited strong virulence against Pi-k~s、Pi-k、Pi-k~p、Pi-z、Pi-b、Pi-7、Pi-CO39,and moderate virulence against the Pi-a,Pi-i,Pi-kh and Pi-3.Overall,the virulence frequency was highest at 83.02%when against the resistance genotype Pi-1.However,it was lowest to genotype Pi-3 at 37.74%Twenty-one representative isolates that have known avirulence genes were in vitro inoculated on forty-eight mainly planted rice varieties in Taojiang.According to the types of resistance and susceptibility,the forty-eight tested rice varieties were divided into six categories by cluster analysis.The resistance genotype Pi-kp,Pi-k~s,Pi-3 have the highest resistance frequency,followed by Pi-a,Pi-I,Pi-kh,Pi-ta,Pi-sh,Pi-7,Pi-CO39.Pi-19 has the lowest resistance frequency.These results indicated that the resistance of Pi-19 was almost lost in rice varieties and this genotype cannot be planted in Taojiang,while the varieties containing resistance genes Pi-k~p,Pi-k~s,Pi-3 have better utility value.In the implementation of green comprehensive prevention and control measures in disease of late rice in Taojiang,we found that there is a significant difference between the biocontrol and chemical agents in field use.In seed dressing,biological agents can promote germination of seeds when compared to chemical agents.In the prevention and control of rice blast and sheath blight disease,there has no significant difference between the use of biological agents and chemical pesticides.The biological agents JN005,JN369,and YN145were performed well in the green prevention and control of rice disease in terms of prevention and control of rice blast and the yield.