Study On Soil Microbial Diversity And Antagonistic Activity Of Potato In Different Planting Patterns

Potato is one of the four major food crops in the world,which has the advantages of high yield and high economic benefits.Potato continuous cropping leads to the decline of potato yield and quality,and the obstacle of potato continuous cropping is becoming more and more serious.But reasonable rotation can break the barrier of continuous cropping and protect the health of potato.In this study,five different planting patterns were set up to analyze the effects of different planting methods on the number of main pathogens of potato through the changes of soil culturable microorganisms,soil enzyme activity,abundance changes of main pathogenic bacteria and soil microbial diversity,to explore the basis of biocontrol of potato fungal diseases and to provide data support for the control of major potato diseases.The main research results are as follows:(1)The results of culturable microbial quantity determination showed that there was no obvious change in the number of microorganisms in different planting methods,but the number of soil fungi under continuous cropping was higher than that of rotation,and the number of soil bacteria decreased and the number of fungi increased.Soil changed from bacterial type to fungal type.(2)Spring wheat-potato rotation(A),spring wheat-naked oat rotation(B),naked oat-potato rotation(C),naked oat-soybean rotation(D),pea-potato rotation(E),potato continuous cropping(F),the activities of catalase and polyphenol oxidase in soil reached the maximum at the seedling stage in 2019.The catalase activity at the seedling stagewas 36.24 ?mol/d/g,31.91 ?mol/d/g,39.56 ?mol/d/g,35.97?mol/d/g,42.59 ?mol/d/g,34.30 ?mol/d/g in 2019.The activities of polyphenol oxidase in soil at seedling stagewas 163.36 mg/d/g,178.36 mg/d/g,168.64 mg/d/g,141.60 mg/d/g,154.40 mg/d/g,166.48 mg/d/g in2019 The activities of urease and sucrase reached the maximum during the expansion period in 2019.At the expansion period in 2019,the urease activity was 1073.70 ?g/d/g,916.04 ?g/d/g,980.98 ?g/d/g,1094.47?g/d/g,1202.05 ?g/d/g,1179.75 ?g/d/g,at the expansion period in 2019,the sucrase activity was 105.39mg/d/g,76.25 mg/d/g,77.96 mg/d/g,62.21 mg/d/g,76.81 mg/d/g,44.26 mg/d/g.The enzyme activity in 2019 is higher than that in 2018.(3)The results of microbial diversity sequencing showed that the composition of soil fungal community was significantly different under different planting methods,but the difference of bacterial community composition was not significant.The OTU number of different rotation patterns in 2019 was higher than that of continuous cropping.Under rotation,the richness and diversity of fungal community were higher than that of continuous cropping.At the seedling period in 2019,the diversity and richness of bacterial community under rotation were higher than that of continuous cropping.At the expansion period in 2018,the richness of bacterial community was higher than that of continuous cropping.Under different planting patterns,the dominant phylum of fungi were Ascomycota,Mortierellomycota and Basidiomycota,the dominant genus were Mortierella,Gibberella and Fusarium.The dominant phylum of bacteria were Actinobacteria,Proteobacteria and Chloroflexi.The dominant genus were Arthrobacter,Nocardioides and Sphingomonas.Crop rotation could increase the abundance of Mortierella,Chaetomium and Arthrobacter in soil,while decrease the abundance of Gibberella and Fusarium in soil.The results of correlation analysis of environmental factors showed that soil polyphenol oxidase,urease,sucrase and catalase significantly affected the community composition of fungi and bacteria,and had significant correlation with phylum and genus in the community composition of fungi and bacteria.(4)The quantitative results of pathogens of potato diseases showed that the numbers of Verticillium dahliae and Fusarium solani in different periods were at a high level under F,and the number of Verticillium dahliae was the highest at the seedling period in 2019 under,F,which was as high as52.52*103copie/g,and the difference was significant.(5)The results of antagonistic bacteria screening showed that a total of 5 antagonistic bacteria were screened.Strain YM128 had the highest inhibition rate against Rhizoctonia solani,Fusarium solani and TD2(Fusarium graminearum),which were 94.15%,49.57% and 71.86%.Strain YM93 had the highest inhibition rate of TD1(Fusarium sambucinum),which was 86.05%,which was significantly higher than that of other strains.(6)The results of control effect of antagonistic bacteria showed that one month after inoculation with strain TD1(Fusarium sambucinum),a large area of disease spot was observed in the potato inoculated with strain TD1(Fusarium sambucinum),and a small area of disease spot was also observed in the potato sprayed with antagonistic bacteria XM23 and P76,while there was no disease spot in the potato sprayed with antagonistic bacteria YM93,YM128 and YM173,and the control effect was better.The weight loss rate and hardness of potato were measured at 2 months.The results showed that the weight loss rate of potato inoculated with strain TD1 was 5.32%,and that of potato sprayed with antagonistic strain XM23 was 18.81%,which was significantly higher than that of other treatments.The weight loss rate of potato sprayed with antagonistic strain YM173 was lower and the effect was better.Based on the results of the inhibition rate of the strain and the control effect of the strain on potato,YM173 was selected as an antagonistic strain with good bacteriostatic effect,which was preliminarily identified as Bacillus amyloliquefaciens.