Diversity Analysis Of Bacteria And Fungi In Rhizosphere Soil Of Panax Notoginseng Under Different Water And Fertilizer Conditions And Screening Of Endophytic Antagonistic Bacteria

Panax notoginseng is a valuable traditional Chinese medicine,which has the effect of promoting blood circulation,removing blood stasis,reducing swelling and relieving pain.It likes warmth and dampness,mainly depends on artificial planting,and has strict requirements on the amount of irrigation.Compound microbial fertilizer contains a large number of beneficial microorganisms and organic matter,which can not only improve soil fertility but also improve soil microecological environment,and then promote crop growth and plant resistance.Irrigation and fertilization are the main measures of agricultural production,which have an important impact on crop growth and soil microorganisms in planting areas.The changes of soil microorganisms in the rhizosphere of P.notoginseng under different water and fertilizer coupling conditions are very important for the healthy planting of P.notoginseng.The purpose of this study is to explore the changes of microbial diversity and community structure in rhizosphere soil under different water and fertilizer conditions to provide theoretical reference for the scientific planting of P.notoginseng.The subjects of this study were P.notoginseng rhizosphere microorganisms planted in the southwest of Luxi County,Honghe Prefecture,Yunnan Province.Three irrigation methods were set up: low water(J1),high water(J2)and high-low water alternating irrigation(J3),and two different amounts of low fertilizer(F1)and high fertilizer(F2).The control group was CK(normal water,no fertilizer),irrigated once a week and fertilized once a month.Adopt the form of sprinkler irrigation with the integration of water and fertilizer.The rhizosphere soil of P.notoginseng was collected under different treatments,and the soil bacterial 16 Sr DNA gene and fungal ITS1 gene were sequenced by high-throughput sequencing,the sequence data were counted,and OTU,Alpha diversity,Beta diversity and community structure were analyzed to explore the effects of different water and fertilizer conditions on the microbial diversity in the rhizosphere soil of P.notoginseng.Meanwhile,the strains with antagonistic effect against pathogens were screened from the endophytic bacteria of P.notoginseng.The main results of this thesis are as follows:(1)According to the analysis of bacterial diversity in rhizosphere soil of P.notoginseng under different water and fertilizer conditions,about OTU analysis,the number of OTU in CK group(normal water,no fertilizer)was the lowest,the number of OTU in F1(low fertilizer)was higher than that in F2(high fertilizer),and the number of OTU in J2(high water)treatment was higher than that in J1(low water)and J3(alternate irrigation)treatments.Concerning Alpha diversity analysis,the bacterial richness,number and community diversity of CK group(normal water,no fertilizer)were the lowest,while the six treatments with microbial fertilizer were significantly higher than the control in the above three aspects.Compared with different amounts of fertilization,F1(low fertilizer)is more conducive to the increase of bacterial richness and number.Compared with different irrigation groups,J2(high water)treatment had higher species number and diversity.From the point of view of Beta diversity,compared with different amounts of fertilization,the similarity between fertilization(F1,F2)groups was higher than that of non-fertilization CK treatment.Compared with seven groups of water and fertilizer treatments,CK group(normal water,no fertilizer),J1F2(low water,high fertilizer)and other treatments had very low similarity.(2)Analysis of bacterial community structure in rhizosphere soil of P.notoginseng under different water and fertilizer conditions,the higher abundance of phyla were Proteobacteria,Firmicutes and Bacteroidetes.The community structure of bacteria in each treatment was different at class,order,family and genus level.The six groups of different microbial fertilizer treatments set up in the experiment increased the abundance of many beneficial bacteria,such as Proteobacteria,Acidobacteria,Bacteroidetes,Chloroflexi and Burkholderiales,which improved the diversity of soil bacteria.(3)With regard to the analysis of fungal diversity in the rhizosphere soil of P.notoginseng under different water and fertilizer conditions,there was no obvious rule among the groups of(F)and microbial(J)under different irrigation conditions,and the joint effect of water and fertilizer conditions on fungi was more complex.From the point of view of the number of OTU,the number of OTU in CK group(normal water,no fertilizer)and J2F1(high water,low fertilizer)was less,while the number of OTU in J1F2(low water,high fertilizer)and J3F1(alternative irrigation,low fertilizer)treatment was higher.Compared with J1(low water)and J2(high water)treatment,J1(low water)treatment was more beneficial to the growth of fungi.On Alpha diversity analysis,the richness,quantity and community diversity of fungi in CK group(normal water,no fertilizer)and J2F1 were lower,while those in J1F2(low water,high fertilizer)and J3F1(alternative irrigation,low fertilizer)treatments were very high.According to Beta diversity analysis,the composition of F2(high fertilizer)treatments was similar,while J3F2(alternate irrigation,high fertilizer)and J1F1(low water,low fertilizer)treatments were the most different from other treatments.(4)In the analysis of the fungal community structure in the rhizosphere soil of P.notoginseng under different water and fertilizer conditions,12 fungal phyla were detected in seven groups of samples,Ascomycota,basidiomycetes,Basidiomycota and Mortierellomycota were the most dominant phyla,and soil fungi were different in class,order,family and genus level among different treatments.Except for J3F2(alternate irrigation,high fertilizer)treatments,in general,compared with the control group,the abundance of pathogenic fungi decreased in five different water and fertilizer treatments,such as Aspergillus,Verticillium,Fusarium and Alternaria.The abundance of beneficial fungi,Penicillium and Trichoderma,were similar in seven groups.(5)Bacteria,fungi and actinomycetes were isolated and purified from the endophytic bacteria of P.notoginseng.Seven strains with antagonistic effect against Fusarium oxysporum,the pathogen of P.notoginseng,were obtained by plate confrontation experiment.All of them were identified by molecular biology as Bacillus.