Study On The Microbial Community Structure And Metabolic Characteristics Of Ginseng Rhizosphere Soil In Seedling Beds

Panax ginseng C.A.Meyer is a kind of traditional Chinese medicine with a long history and valuable value.However,due to the long-term intensive cultivation of farmland soil,the soil organic matter content is low and the fertility is poor,leading to the problems of low yield and serious disease in farmland ginseng cultivation.In order to control soil,prevent ginseng diseases,and improve ginseng production,people often overuse fungicides,resulting in environmental pollution such as soil and water sources.Rhizosphere soil is a micro region where plants,soil,and microorganisms interact.Analyzing the changes in nutrients and microbial communities in ginseng rhizosphere soil after planting ginseng has important scientific significance for controlling ginseng diseases.In addition,soil organic matter can effectively provide nutrients for the growth of ginseng,which is composed of active organic carbon and inert organic carbon,while soil active organic carbon and humus components can be used to predict changes in soil quality.Therefore,the exploration of active organic carbon and humus components in soil is also of research significance for finding soil nutrients suitable for the growth of ginseng.In this paper,the structure and composition of soil microbial communities were measured using high throughput techniques in the rhizosphere and non rhizosphere soils of biennial ginseng seedlings in ginseng nursery beds,and the related functions were predicted and analyzed.The basic physical and chemical properties,organic carbon,microbial biomass carbon,water-soluble organic carbon,and humus components and contents of the soil were measured.The correlation analysis between soil factors and microbial communities was conducted,Explore the microbial flora and environmental factors related to ginseng continuous cropping obstacles,provide a basis for controlling ginseng diseases through regulating microbial populations and environmental factors in the future,thereby reducing the use of harmful environmental chemical reagents such as pesticides,and provide a basis for reducing damage to land resources,protecting the ecological environment,and promoting sustainable and healthy development of the environment.The relevant research results are as follows:(1)In ginseng rhizosphere soil,the richness and diversity of prokaryotic microbial community decreased,significantly changing the diversity of soil prokaryotic microbial community structure(P<0.05).The rhizosphere soil is significantly enriched with bacteria such as Actinobacteria,Bacteroides,Firmicutes,and Bacillus.Among them,Firmicutes is a key core species with a negative correlation with six phyla,which can produce spores and resist extreme environments.The relative abundance of Firmicutes in ginseng rhizosphere soil has significantly increased.Glycomyces,Bordetella,and Zymobacter were newly detected in ginseng rhizosphere soil.Tax4 Fun function prediction results showed that soil carbohydrate metabolism,lipid metabolism,xenobiotic biodegradation,and metabolic function abundance increased in the rhizosphere soil.(2)Planting ginseng decreased the diversity and evenness of the eukaryotic microbial community in the rhizosphere soil of ginseng,but had little impact on the alpha diversity and community structure of the eukaryotic microbial community in the rhizosphere soil.Pathogenic fungi such as Humicola and Fusarium are significantly enriched in the rhizosphere soil,and the relative abundance of Enterrhizomycota,Kickxeromycota,and Ochrophyta in the rhizosphere soil is 0.The core species selected,Anthophyta,has a lower relative abundance in the ginseng rhizosphere soil.The FUNGuild function prediction results showed that the functional abundance of various plant pathogens in ginseng rhizosphere soil increased,or had adverse effects on ginseng growth.(3)The results of prokaryotic eukaryotic species association analysis showed that there was a positive correlation between Bacillus and Mortierella in the rhizosphere soil,which were potential biocontrol bacteria that could promote the healthy growth of ginseng.There is a positive correlation between pathogenic fungi such as Humicola and Fusarium in rhizosphere soil and Bacillus,indicating that the increase of pathogenic bacteria induces ginseng to enrich Bacillus to resist diseases.(4)After planting ginseng,the content of pH,organic matter,and available phosphorus in the rhizosphere soil of ginseng decreased,while the content of alkali hydrolyzable nitrogen,available potassium,and electrical conductivity significantly increased,with the most significant increase in electrical conductivity,which reached 493.66%.In ginseng rhizosphere soil,the contents of organic carbon,water-soluble organic carbon,microbial biomass carbon,total extractable humus carbon,humic acid carbon,fulvic acid carbon,and humin carbon all decreased.In addition,the overall performance of △ log K in soil is FA>HA,and the PQ value,Hoover’s ratio,and △ log K value of FA in rhizosphere soil decrease.Planting ginseng makes the molecular structure of fulvic acid carbon in soil humus more complex.(5)The results of correlation analysis between environmental factors and microbial communities showed that soil microbial biomass carbon content had the greatest impact on prokaryotic microbial communities,while pH had the greatest impact on the composition and function of eukaryotic microorganisms.The pathogenic fungus Humicola has a significant positive correlation with electrical conductivity,alkaline nitrogen,and available potassium content,while a significant negative correlation with water-soluble organic carbon.The pathogenic fungus Fusarium has a negative correlation with fulvic acid carbon and total extractable humus carbon.The prokaryotic microbial community in rhizosphere soil has a positive correlation with pH and available potassium,while the eukaryotic microbial community has a positive correlation with organic matter and microbial biomass carbon.Based on the above results,ginseng cultivation increased the content of alkali hydrolyzable nitrogen,available potassium and electrical conductivity in the rhizosphere soil.pH,organic matter,available phosphorus,organic carbon,water-soluble organic carbon,microbial biomass carbon,total extractable humus carbon,humic acid carbon,fulvic acid carbon,humin carbon content,PQ value and ratio of humin to humin in the rhizosphere soil showed a downward trend.Alternatively,it may be possible to adjust environmental factors related to pathogenic bacteria to resist diseases.In addition,planting ginseng decreased the richness and diversity of microbial communities in the rhizosphere soil of ginseng,had a small impact on the diversity of soil eukaryotic microorganisms,and significantly changed the diversity of soil prokaryotic microorganisms.The growth of ginseng promotes the enrichment of beneficial bacteria such as Actinobacteria,Bacillus,and Firmicutes in the rhizosphere soil,which helps to inhibit the growth of pathogenic bacteria and reduce the occurrence of ginseng diseases.However,the relative abundance of pathogenic fungi Humicola and Fusarium in the rhizosphere soil of ginseng has also increased,and biological control can be carried out against such pathogenic bacteria in combination with actual conditions.Changes in nutrient content in the rhizosphere soil can cause changes in the structure of soil microbial communities.Both decreased nutrient content and changes in the structure of microbial communities may cause ginseng diseases.By artificially adjusting the soil nutrient content and the number of beneficial bacteria,it may promote the healthy growth of ginseng.