Comparison Of Resistance Of Different Cotton Varieties(Lines) To Fusarium Wilt Of Cotton And Biocontrol Evaluation Of Microbial Seed Coating Agent

Fusarium wilt of cotton is a kind of fungal disease which mainly damages vascular bundles.It damages cotton plants by blocking ducts and producing toxins.In this study,40 cotton varieties with different resistance to Fusarium wilt were selected for resistance identification and yield traits analysis by artificial inoculation.The susceptible and resistant varieties identified by cotton Fusarium wilt resistance were used as target materials.The indoor virulence of three kinds of low toxicity fungicides was determined and the field control effect and growth promotion test was carried out.Then the seed coating agent produced by antagonistic bacterium KX-33 was compared with the high-efficiency and low toxicity fungicide to explore its indoor control effect,To provide a scientific theoretical basis for the rational use of pesticides,provide germplasm resources for the study of biological control of cotton Fusarium wilt,provide a theoretical basis and scientific basis for the breeding and biological control of Cotton Fusarium wilt.The results show that:(1)40 cotton germplasm resources were identified for Fusarium wilt resistance.The results showed that in the resistance identification in 2019,06-146 and Xinhai 14 progenies could produce resistant hybrid progenies,in which the progenies with high resistance and disease resistance accounted for 41.67%of all progenies.In the disease resistance identification in 2020,06-146 and Xinhai 14 progeny could produce resistant hybrid progeny,in which the progeny with high resistance and disease resistance accounted for33.33%of all progenies in the hybrid population.Through the correlation analysis of Fusarium wilt resistance and yield traits of 40 cotton varieties,it was found that the relative disease index of cotton in2019 and 2020 had a very significant negative correlation with lint percentage.There was a significant negative correlation between disease index and boll weight in 2019.In 2020,the disease index of cotton was significantly negatively correlated with boll weight and seed number per boll.(2)The inhibition test of three fungicides on cotton Fusarium wilt showed that different concentrations of fungicides inhibited the mycelial growth of cotton Fusarium wilt,and the inhibition effect was stronger with the increase of concentration.Among the three fungicides,80%allicin EC had the highest inhibition rate against Fusarium oxysporum f.sp.,100 billion/g Bacillus subtilis WP was lower than that of 80%allicin EC,and 30%oxamyl water had the lowest inhibition rate.The results showed that the indoor toxicity was:80%allicin EC>30%oxamyl water>100 billion/g Bacillus subtilis WP.The results showed that the field control efficiency of all treatments during the whole investigation period:80%allicin EC>30%oxamyl water>100 billion/g Bacillus subtilis WP.(3)The pot experiment showed that the seed coating agent containing KX-33 could significantly improve the germination rate and fresh weight of buds,shorten the germination time,1×10~8 CFU/mL microbial seed coating agent treatment can significantly improve cotton plant height.On the 45th day after inoculation,The control effect of 1×10~8 CFU/mL microbial seed coating agent on two varieties of cotton was the best,which were 65.35%and 63.77%respectively,and were higher than that of the chemical control,which had good application value for microbial seed coating agent to control cotton Fusarium wilt.