Inoculation Technique Of Fusarium Spp.causing Maize Ear Rot And Identification Of Resistance Of Maize Varieties To Maize Ear Rot

Maize ear rot is an important disease in maize.when the maize is infected with ear rot pathogen,it will cause the decrease of corn yield.The toxin produced by the pathogen will contaminate the grain and affect the quality of corn,which threat to human and animal health.In recent years,under the influence of the changes of cultivation and tillage system,the increase of planting density of corn and climate change,the incidence of ear rot of corn has become more and more serious,which seriously affects the high yield,stable yield and good quality of corn.In this study,the biological characteristics of Fusarium verticilliorde,F.graminearum and F.proliferatum isolated from Anhui Province were tested.On this basis,the pathogenicity of different species of Fusarium was studied by field experiments.The effects of different artificial inoculation methods and inoculation time on the incidence of corn ear rot were studied.In addition,318 maize varieties provided by Anhui Provincial Seed Management Station were identified for their resistance to ear rot,and the identification results were of great significance for screening resistant cultivars to ear rot.The main results are as follows:(1)The mycelial growth rate and conidia production of 4 F.graminearum,5 F.proliferatum strains and 7 F.verticilliorde strains were tested.The results showed that there were significant differences in the mycelial growth rate and sporulation amount of the same Fusarium species.Ingrowth rateof mycelial,Fg TTZ-6 was the fastest,and Fg HF-5 was the slowest among the 4 strains of F.graminearum.Among the 5 strains of F.proliferatum,the mycelial growth rate of Fp HF-1 was the fastest and Fp HB-29 was the slowest.Among the 7 tested F.verticilliorde,the mycelial growth rate of Fv FY-57 was the fastest and Fv HF-5 was the slowest.Inconidia production,Fg TTZ-5produced the most conidia and Fg HF-6 was the least among the four F.graminearum strains.Among the five F.proliferatum strains,Fp SZ-32 produced the most sporulation,,while strain Fp HB-29 produced the least sporulation.Fv FY-57 produced the most sporulation and Fv BB-22 had the lowest sporulation among the seven F.verticilliorde strains.(2)The pathogenicity of F.graminearum,F.proliferatum species and F.verticilliorde to maize was studied by artificial inoculation method.The results showed that there were significant differences in the disease index of corn ear rot after inoculation of F.verticilliorde,F.proliferatum and F.graminearum.The pathogenicity of F.verticilliorde was the strongest among the testes three species of Fusarium.The average disease index of F.verticilliorde on handan 777 and longping206 was higher than that of F.proliferatum and F.graminearum.(3)The effects of inoculation method and inoculation time on the incidence of corn ear rot were studied.The results of the inoculation method showed that the incidence of ear rot was the most severe by the mid-ear injection method,followed by filament channel injection,and the least severe by the mid-ear double toothpick method.There were significant differences in the disease index of ear rot of maize inoculated at different time after silking.The earlier the inoculation,the more severe the disease.The disease index of ear rot inoculated at 1 d,4 d and 7 d after maize silking was more than 40%,which suggested that the susceptibility period of ear rot of maize in the field might be concentrated at 1 to 7 d after maize silking.A regression model was established for different inoculation time and incidence of ear rot of Fusarium spp.(4)Breeding and utilization of resistant varieties are important measures to control c orn ear rot.The results of resistance identification test showed that there were5 varieties showed high resistance(HR),accounting for 1.5% of the total tested varieti esamongthe tested318 corn varieties.227 varieties showed resistance(R),accounting f or 71.38% of the tested varieties;83 varieties showed moderate resistance(MR),acco unting for 26.1% of the total tested varieties;3 showed susceptible(S),accounting for0.94% of the total tested varieties.From the identification results,it can be seen that among the currently cultivated varieties(lines),there are few corn varieties with high resistance to ear rot.