Study On The Inhibitory Effect Of Vermicompost Substrate On Tomato Fusarium Wilt

Fusarium wilt is one of the most common and harmful diseases of tomato.The economic benefit of tomato planting is good,which leads to the continuous cropping pattern of tomato in many places.Then the soil microbial species and community structure were unbalanced.Moreover,farmers' lack of prevention and control of tomato soil-borne Fusarium wilt makes tomato Fusarium wilt become a disadvantage restricting the development of tomato industry in China.One of the main determining factors to ensure the healthy growth of crops is soil health,and microorganisms play a very important role in maintaining soil health.Microbial diversity and community structure are important factors affecting the prevention and control of soil-borne diseases.The study on the structure of soil microbial community in healthy soil and diseased soil of tomato and the analysis of the factors affecting the composition of soil microbial community is an important basis for the control of soil-borne diseases of tomato.Therefore,in this study,Illumina Miseq high-throughput sequencing technique was used to analyze the functional diversity and structural diversity of microbial community,and the soil microbial community and soil disease inhibition ability were clarified.The main results are as follows:(1)The effect of vermicompost on antioxidants in tomato plants.In the healthy group,vermicompost treatment increased the activity of SOD and POD,but there was no significant difference in SOD activity and POD activity between the vermicompost treatments and the control treatment in pathogen group.The activity of MDA increased gradually with the growth period of tomato,and the content of MDA decreased by vermicompost treatments.(2)Effect of vermicompost on the number of microorganisms in tomato soil.Vermicompost treatments increased the number of bacteria and actinomycetes in soil and decreased the number of soil fungi and pathogens.The incidence of tomato Fusarium wilt decreased significantly with the increase of the proportion of vermicompost.The highest incidence of CK treatment was 70.5%,and the lowest incidence of 1:1P treatment was 17.4%.There was a significant positive correlation between the incidence of tomato Fusarium wilt and the number of pathogens in soil.(3)Isolation and identification of antagonistic bacteria against Fusarium wilt in vermicompost.216 strains were isolated from vermicompost soil.The antagonistic effects of 29 strains of bacteria on fungal pathogens FOL1,FOL2,Rhi and Phy were observed by plate confrontation method.The results showed that antagonistic bacteria JG-3,JG 5,JG 13,JG 20,JG-23 and GJ had antagonistic effects on four kinds of fungal pathogens,and the bacteriostatic zone of tomato Fusarium wilt pathogen FO1 was more than 11mm.These strains were selected for the control effect of greenhouse diseased soil.The incidence of tomato Fusarium wilt was positively correlated with the number of pathogens in soil.The number of tomato Fusarium wilt treated with antagonistic bacteria JG was 1.23×104/g soil,and the lowest incidence was 4.3%.It significantly reduced the incidence of tomato Fusarium wilt.The antagonistic strain GJ was identified as Bacillus subtilis by morphology,physiology and biochemistry and 16s rRNA sequencing.(4)Effect of vermicompost on soil microbial Alpha diversity.In the bacterial community of the pathogen group soil,vermicompost treatments significantly increased the Shannon Weiner diversity index of soil microorganisms.The Chaol index in vermicompost treatments were higher than that in CK treatment,but the difference was not significant.The ACE index of 1:0P?1:1P and 1:3P vermicompost treatments was significantly different to that of the control treatment.In the soil fungal community of the pathogen group,the Chaol index and ACE index of each vermicompost treatment were higher than those of the CK treatment.The results of correlation test showed that the incidence of tomato Fusarium wilt was negatively correlated with the Shannon index of bacteria and fungi,but did not reach a significant level,and there was a significant negative correlation between the incidence of tomato Fusarium wilt and the ACE,Chaol index of bacteria and fungi.The incidence rate was positively correlated with the Simpson index of bacteria and fungi,but it did not reach a significant level.(5)Effect of vermicompost on soil microbial structure.At the level of the phylum,the dominant bacteria in the healthy group were Proteobacteria,Bacteroidetes,Chloroflexi,Actinobacteria,Acidobacteria,Gemmatimonadetes,Firmicutes,Planctomycetes.The dominant bacteria in the pathogen group were Proteobacteria,Bacteroidetes,Actinobacteria,Chloroflexi,Saccharibacteria,Gemmatimonadetes,Acidobacteria,Parcubacteria and Firmicutes.Compared with the healthy soil with the same proportion of vermicompost,the relative abundance of Actinobacteria,Firmicutes and Chloroflexi in the pathogenic soil were increased.At the phylum level,the common dominant fungus in the two groups was Ascomycota.In the vermicompost treatments of the pathogenic group,the dominant communities of soil fungi were Ascomycota,Basidiomycota and Zygomycota.Compared with the same proportion of vermicompost in the healthy soil,the relative abundance of Basidiomycota,Zygomycota and Chytridiomycota were decreased in pathogenic soil.In addition,compared with soil treatment CKO,vermicompost treatments of the healthy group increased the abundance of Ascomycota and decreased the abundance of Basidiomycota.(6)Pearson correlation analysis of microbial community at phylum level showed that there was a significant positive correlation between the relative abundance of Proteobacteria and Verrucomicrobia and the incidence of tomato Fusarium wilt,while there was a significant negative correlation between Deinococcus-Thermus and the incidence of tomato Fusarium wilt.In soil microbial community,the relative abundance of Actinobacteria and Chloroflexi was positively correlated with available phosphorus and water content,while the relative abundance of Verrucomicrobia was negatively correlated with N,P,K and water content.However,there was a significant negative correlation between Parcubacteria and water content.The correlation between the relative abundance of other dominant communities and soil physical and chemical properties was not significant.