Studies On Biological Control Of Gliocladium Virens Against The Northern Leaf Blight Of Corn

The pathogen of Exserohilum turcicum was isolated from the infected leaf of maize in suburb of Ya-an, Sichuan.46 strains of Gliocladium virens were isolated from different soil in Ya-an. According to the source and strain on the growth in PDA medium with different characteristics,14 strains were selected, used as the tested strains with the 16 strains kept in the lab together.the experimental results of Exserohilum turcicum hyphal growth, sporulation and other biological characteristics showed that:the optimum hyphal growth conditions were full light,25℃, pH6, PDA medium; while the optimum conditions for sporulation were all dark,25℃, pH 6, water agar medium.In the dual test of G. virens and the pathogen,the hyphal growth of Exserohilum turcicum was inhibited by G3 with inhibition rate of 59.12%. The non-volatile metabolites of G.virens G3 and G8 had the best inhibition rates,64.20% and 63.64%;respectively, G37 had the lowest inhibition rate-42.50%. The result of the volatile metabolites of G.virens showed that G8 had the inhibition rate which was 45.00%, while G37 had the lowest inhibition rate which was 21.00%.The result of the disease resistance evaluation indicated that 10ks3-4 had the highest disease index,while 10117002 had the lowest. The disease index of 12% General Materials was more than 30.00, and 10% less than 10.00. Of all these materials,10117's Disease rate and disease index were both low, but 10ks'were opposite.Useing SA,Oxalic acid and G.virens. fermentation liquor to induce corn northern leaf blight,the enzymatic activity of indoor experiment showed that PPO and PAL enzymatic activity of resistant species was higher than susceptible species.The activity of PPO and PAL were positive correlation with variety resistance. Under the induction of SA,the activity of PPO and PAL of all varieties plants had the greatest changes. Under the induction of G.virens. fermentation liquor was worse than that,but better than Oxalic acid. In short, the changes of the activity by these treatments were greater than confrontation experiment. In the experiment of farmland, the changes of enzymatic activities of PPO and PAL were consistent with the result of indoor'。The survey of disease resistance of farmland experiment demonstrated that the best effect of induced resistance was FUYU 1-48.89% by the treatments of SA.The worst was CHUANDAN 21-16.04% by the treatments of Oxalic acid. It was obviously that SA had the optimal induced effect under the same sspecies.And the effect of induced resistance expressed by susceptible species was worse than resistant species.