Preliminary Study On The Effects Of Bacillus And Trichoderma On Cucumber Disease Prevention And Growth Promotion

As a microorganism widely used in the biological control of plant diseases,biocontrol bacteria mainly include biocontrol fungi and biocontrol bacteria.In biocontrol bacteria that currently have been developed,biocontrol fungi are mainly Trichoderma,and the biocontrol bacteria are mainly Bacillus,and they become research hotspots at home and abroad.The current biocontrol bacteria have been widely used in agriculture and animal husbandry production,plant disease and insect control,maintaining the biodiversity of plant micro-ecosystems,and maintaining the ecological balance of farmland.In this study,cucumber was used as the experimental material,and the experiment of seeds treated with 64 biocontrol Bacillus strains with antagonistic activity,which obtained in the early stage,was carried out to promote the germination effect of cucumber seeds,and hoped to screen out the Bacillus with biocontrol and growth-promoting efffecs.The classification and identification of Bacillus with extremely significant growth-promoting effect were carried out by macular method,and the inhibitory effects of these Bacillus on Didymella maculosa were further clarified.In addition,experiments of the control effects of biocontrol Trichoderma on cucumber vine blight and other diseases were carried out,and the effects of different application methods of biocontrol Trichoderma on cucumber plant growth were observed.The research aimed to lay the foundation for the development and utilization of biocontrol bacteria.The main research results were as follows:Through preliminary screening and ermination experiments after seed soaking treatments of different concentrations of biocontrol Bacillus suspension and cucumber seed treatments of different experimental equipment,obtained the screening experimental method of effect of seed soaking treatment of Bacillus suspension on cucumber growth promotion.Then,using the screening experimental method of the growth-promoting effect of the bacterial suspension on cucumber,the growth-promoting effects of the 64 strains of Bacillus,which had been obtained in the early stage and had growth-promoting effects on variety of pathogens were screenedThrough the growth promotion experiment,34 strains of Bacillus with remarkable growth promotion effect on cucumber seeds were screened out,among which 26 strains had extremely remarkable growth promotion effect.Through molecular biological identification of the Bacillus obtained by screening,the Bacillus with growth promoting effect were initially identified.Among them,the Bacillus with significant growth promoting effect were: Bacillus velezensis 10 strains;Bacillus subtilis14 strains;Bacillus amyloliquefaciens 2 strains;Paenibacillus polymyxa 1 strain;Bacillus licheniformis 2 strains;Bacillus siamensis 1 strain;Bacillus methylotrophicus 1 strain;Bacillus halotolerans 1 strain.Bacillus with extremely significant growth promotion effect were: Bacillus velezensis 6 strains;Bacillus subtilis 13 strains;Bacillus amyloliquefaciens 2strains;Paenibacillus polymyxa 1 strain;Bacillus licheniformis 2 strains;Bacillus methylotrophicus 1 strain;Bacillus halotolerans 1 strain.Through the evaluations of the antagonistic effects of 26 strains with extremely significant growth-promoting effects to Didymella maculosa,Bacillus subtilis 5 strains with strong antagonistic activity to Didymella maculosa,Bacillus subtilis 4 strains and Bacillus amyloliquefaciens 1 strain with moderate antagonistic activity to Didymella maculosa,and Bacillus velezensis 7 strains,Bacillus subtilis 2 strains,Bacillus amyloliquefaciens 2 strains,Bacillus polymyxa 1 strain,Bacillus licheniformis 2 strains,Bacillus methylotrophic 1 strain and Bacillus halotolerans 1 strain.The plate confrontation experiments of Trichoderma atroviride Tr1206 with high-activity obtained in the early stage with Didymella maculosa,Fusarium oxysporum,Rhizoctonia solani,Botrytis cinerea were carried out,and observed inhibitory effects of Trichoderma atroviride Tr1206 on 4 kinds of pathogenic bacteria.The results showed that: in the results of the confrontation experiment,Trichoderma atroviride Tr1206 was found to have obvious inhibitory and erosive effects on Didymella maculosa,Fusarium oxysporum,and Rhizoctonia solani.The growth of the three pathogenic bacteria was inhibited by Trichoderma atroviride Tr1206 and covered by growth.The effect of Trichoderma atroviride Tr1206 on the prevention and control of cucumber seedling blight showed that the preventive application of Trichoderma atroviride had better effects on cucumber chlorophyll,plant height and disease prevention than that of curative application,effects were very remarkable especially when the application of Trichoderma atroviride Tr1206 was carried at 24 h before the inoculation of pathogenic bacteria.The preventive application of Trichoderma atroviride Tr1206 had a better effect on preventing Didymella maculosa infection and pathogenicity than curative application.The reason might be that Trichoderma atroviride inhibited the infection and pathogenicity of pathogenic bacteria.At the same time,Trichoderma atroviride can also be used to induce and stimulate plant defense mechanisms before the plant’s onset period of colonization and prevention..Through experimental effects of Trichoderma atroviride and Trichoderma harzianum bacterial agents interaction with cucumber pathogens on cucumber chlorophyll results found that during Trichoderma harzianum and Trichoderma atroviride bacterial agents were applied to cucumber plants and interactions with infected Didymella maculosa,Fusarium oxysporum,Rhizoctonia solani,Botrytis cinerea,they could effectively increase the chlorophyll contents of cucumber leaves at the stage when the cucumber still did not show symptoms at the initial infection.Among them,foliar spray,root irrigation,and spray and root irrigation three treatments of Trichoderma atroviride and Trichoderma harzianum bacterial agents had strong inhibitory effects on cucumber infection and pathogenicity by Didymella maculosa,Fusarium oxysporum and Stemphylium solani,indicated that in the interactions with these three pathogens,Trichoderma might have a stronger effect on inducing cucumber disease resistance,which might be related to the slower infections of the three pathogens.The results of the interaction experiments between Botrytis cinerea,Rhizoctonia solani and Trichoderma showed that Trichoderma atroviride had more obvious effect than that of Trichoderma harzianum in improving chlorophyll,and spray and root irrigation treatment was better than foliar spray and root irrigation,respectively,which indicated that the prevention and control effect of Trichoderma atroviride bacterial agent on Botrytis cinerea caused by Botrytis cinerea and Rhizoctonia solani caused by Rhizoctonia solani was better than that of Trichoderma harzianum bacterial agent,and it was the common result of inducing disease resistance and bacteriostasis.