Screening And Evaluation Of Biocontrol Potential Of Compound Antagonism Against Tobacco Black Shank

There are many shortcomings in the application of single biocontrol agents in the field.In order to overcome the deficiency of a single microbial agent,we have developed a composite microbial agent composed of various antagonistic antibacterial agents FP246 using co-culture approach.The FP246 can significantly reduce the incidence of tobacco black shank.The results were as followed:1.In this study,three Bacillus strains B.safensis YJC-4,B.subtilis CY106 and B.subtilis CY111 were screened out with high antagonistic activity,which could significantly control tobacco black shank disease and promote the tobacco growth.The three strains were further developed into a composite microbial agent FP246.The optimal mixture ratio of composite biological agents FP246 was 3:5:3,and the average inhibitory rate was 90.55%.The average control effect of greenhouse pot experiment was 85.40%.The average control effect was 81.06%.2.The optimal culture pH of composite biological agents FP246 was 8.0,the optimum culture time was 60 h,and the optimum culture temperature was 30 °C.3.The functional diversity of rhizosphere soil microbial community was analyzed by Biolog-ECO after FP246 treatment.Compared with the control,the composite biological agents FP246 significantly increased the average color change rate of soil microbes(AWCD)and the soil microbial community metabolic diversity index,and increased the soil microbial richness.At the same time,it enhances the utilization and fecundity of soil microbes on carbon,4.The results of enzyme activity measurement showed that the defensive enzyme activities of different types of tobacco plants was increased after the application of the composite biological agents FP246.Among them,the enzyme activity of Superoxide dismutase(SOD)and Peroxidase(POD)were obviously increased.Moreover the Malondialdehyde(MDA)content was slightly increased,but much lower than the control treatment.This indicates that the application of the compound antagonistic FP246 can promoted the activity of defense enzyme,inhibited the infection of pathogenic bacteria and improved the plant resistance.