Effects Of Rhizosphere Microbial Structure Reconstruction Based On Biological Fertilizer On Growth And Quality Of Panax Quinquefolium L.

Panacis Quinquefolii Radix has the efficacy of invigorating qi,nourishing yin,clearing heat and promoting salivation.It is considered as a tonic for "tonifying but not dryness",and is the raw material of many Chinese patent medicines and health products.Panax quinquefolium L.is a continuous cropping medicinal plant,which is generally harvested 3-5 years after sowing.However,serious root diseases and the use of a large number of pesticides and fertilizers have seriously affected its quality and drug safety.Root-knot nematode disease of American ginseng is one of root diseases of American ginseng,which can reduce the yield of P.quinquefolium by more than 70%in severe cases,and has a serious adverse effect on the yield and quality of P.quinquefolium.In addition,the wound invaded by pathogenic nematodes can become the invasion port of rust and root rot pathogens,thus aggravating the loss of production.In order to prevent and control root-knot nematode diseases,pentachloronitrobenzene or chloropicrin with high toxic pesticide content of 98%is often used as soil disinfectant for soil disinfection in production.However,these pesticides have stable chemical properties,with a residual period of up to 60 years,which has adverse effects on drug safety,sustainable utilization of soil and human life and health.Soil beneficial microorganisms play an important role in promoting plant growth,accumulating effective components and degrading pesticide residues.It is of great practical significance to introduce compound biological fertilizer with beneficial microorganisms as raw materials into the ecological cultivation of American ginseng for providing high-quality and safe American ginseng medicinal materials.As a key member of soil micro-ecosystem,rhizosphere microorganisms of medicinal plants are closely related to soil function and health of medicinal plants.In this study,metagenomics technology will be used to analyze the effects of biofertilizers on the structure and composition of rhizosphere microorganisms,as well as on the yield and quality of American ginseng,in order to explore the application prospects of different types of biofertilizers in western ecological cultivation.The findings are as follows:(1)The application of the biofertilizer of the No.1 biofertilizer+50 potassium biofertilizer,the gulefeng polyglutamic acid biofertilizer and the garbage enzyme biofertilizer increased the yield of P.quinquefolium by 83.84%(P<0.01),88.61%(P<0.010)and 56.33%(P<0.05),respectively,while the gulefeng polyglutamic acid biofertilizer and the garbage enzyme biofertilizer reduced the incidence of root-knot nematode disease of P.quinquefolium(57.25%and 64.35%respectively,P<0.05)Metagenomics analysis showed that the relative abundance of soil beneficial microorganisms,such as Nordella and Nitrospira related to biological nitrogen fixation,Chaetomium,Microascus and Xylaria related to plant pathogen prevention and control,and Hyphomicrobium related to heavy metal adsorption increased significantly,while the relative abundance of pathogenic microorganisms Plectosphaerella and Rhizobacter decreased significantly.(2)Metagenomics analysis showed that the relative abundance of plant growthpromoting microorganisms,such as Bacillus and Lactococcus,decreased significantly after two years of continuous cropping,while the relative abundance of pathogenic microorganisms Fusarium and Phaeosphaeria increased significantly.After applying biofertilizer for two consecutive years,it was found that the relative abundance of microorganisms with plant growth promotion,environmental restoration or plant pathogen control,such as Cladophialophora,Exophiala,Gymnoascus,Leptodontidium,Metarhizium,Mortierella,Paraphaeosphaeria and Phialemoniopsis,increased significantly.In addition,gulefeng polyglutamic acid biofertilizer,tuxiu biofertilizer+50 potassium biofertilizer and garbage enzyme biofertilizer significantly increased the yield of P.quinquefolium by 44.21%(P<0.01),32.02%(P<0.001)and 20.68%(P<0.05).Gulefeng polyglutamic acid biofertilizer and garbage enzyme biofertilizer significantly reduced the incidence of root-knot nematode disease of P.quinquefolium(57.72%and 66.30%,P<0.05).(3)In the presence of pentachloronitrobenzene,the content in P.quinquefolium leaves was reduced by 64.17%,52.02% and 42.83%(P<0.05),which indicated that the multifunctional biofertilizer had significant degradation effect on pentachloronitrobenzene.Metagenomics analysis showed that the relative abundance of Stenotrophomonas,Ralstonia,Sphingomonas and Pseudomonas involved in the degradation of soil organic pollutants in P.quinquefolium rhizosphere soil increased significantly by 160.16%,117.31%,89.44%and 35.15%(P<0.05),The relative abundance of Gaiella,Penicillium and Pseudogymnoascus involved in the degradation of environmental pollutants in P.quinquefolium rhizosphere soil increased significantly by 114.04%,580.16%and 5937.04%(P<0.05).The results of this study showed that the application of biological fertilizer in ecological cultivation of P.quinquefolium had a significant effect on improving the yield and quality of P.quinquefolium.Biofertilizer significantly increased the yield of P.quinquefolium,reduced the incidence of root-knot nematode disease and the content of pentachloronitrobenzene in P.quinquefolium.The results of metagenomics study showed that the application of biofertilizer had a positive effect on improving rhizosphere microecology of P.quinquefolium.In a word,this study provides a reference for biological fertilizer in ecological cultivation of medicinal plants.