Effects Of Intercropping On Soil Microbial Diversity In Tobacco Rhizosphere

In order to understand the growth and development of tobacco plants under different intercropping conditions,the soil nutrient status of tobacco rhizosphere and the dynamic changes of its microflora structure,finding out tobacco intercropping combinations that have the advantages of intercropping,so as to improve the theoretical basis for tobacco ecological control and continuous cropping obstacles.In this study,tobacco-based crops were selected,and local suitable sweet potatoes(Ipomoea batatas(L.)Lam.),soybeans(Glycine max(Linn.)Merr.),and Chinese herbal medicine salvia(Salvia miltiorrhiza Bge.)were selected as intercropping combinations.The changes of soil nutrients,the development of tobacco plants and the dynamic changes of soil microbial community structure were analyzed.The main results are as follows:(1)The physical and chemical properties of tobacco rhizosphere soil did not change significantly in different treatments.During the growth and development of tobacco,soil p H showed an upward trend,and soil organic matter,total nitrogen,alkali-decomposed nitrogen,available phosphorus,and available potassium showed a downward trend;Tobacco rhizosphere soil organic matter content in intercropping treatment,total nitrogen content is higher than monocropping tobacco,alkali nitrogen content is lower than monocropping tobacco;Salvia / tobacco intercropping,soybean / tobacco intercropping soil available phosphorus content And the content of available potassium is higher than that of sweet potato / tobacco intercropping and tobacco monocropping.(2)Under the intercropping cultivation mode,the agronomic traits of tobacco such as plant height,stem circumference,number of effective leaves,and leaf area are not significantly different.Under the intercropping of Salvia miltiorrhiza / tobacco,each agronomic trait is slightly higher than that of single crop tobacco.(3)Tobacco rhizosphere soil is rich in microbial community composition,and is relatively high during the fast growing period;In general,the diversity of bacterial and fungal communities in intercropping treatments is lower than that in monocropping tobacco treatment,and the richness of bacterial communities is higher than that in monocropping tobacco treatment.The fungus community richness of sweet potato / tobacco and soybean / tobacco intercropping was lower than that of monocropping tobacco,and the fungus community richness of salvia miltiorrhiza / tobacco intercropping was higher than that of monocropping tobacco.(4)The dominant bacterial flora of tobacco rhizosphere soil are: Proteobacteria,Actinobacteria,Acidobacteria,Bacteroidetes,Gemmatimonadetes,Chloroflexi;The dominant fungal flora are: Olpidiomycota,Ascomycota,Mortierellomycota,Basidiomycota;The dominant fungal flora of tobacco rhizosphere soil are: Olpidiomycota,Ascomycota,Mortierellomycota,Basidiomycota;(5)Intercropping has changed the microbial community structure of tobacco rhizosphere soil to a certain extent.In the intercropping treatment,the relative abundance of Proteobacteria,Bacteroidetes,Acidobacteria,Olpidiomycota,Olpidium is higher than that of single-cropping tobacco treatment,Actinomycetes,Green Campylobacter,The relative abundance of Actinomycetes,Chloroflexi,Ascomycetes,Fusarium and Cercophora is lower than that of monocropping tobacco.(6)Bacterial community functional annotation results show: As tobacco grows and develops,the functional genes that exercise metabolism,genetic information processing,and organic systems gradually increase,and the functional genes that perform environmental information processing and human diseases gradually decrease,and the proportion of cellular processes fluctuates;In intercropping treatment,the functional genes of metabolism,genetic information processing,and cellular processes are lower than those of monocropping tobacco treatment,and the functional genes of environmental information processing and human disease functions are higher than monocropping tobacco treatment;(7)Annotated results of fungal community function showed that under intercropping treatment,the relative abundance of symbiotic vegetative fungi in tobacco rhizosphere soil was lower than that of monocropping tobacco treatment.The changes of saprophytic fungi in the soil are more obvious.To sum up,rational intercropping is beneficial to increase the nutrient content of tobacco rhizosphere and increase the richness of soil microbial community in tobacco rhizosphere.Intercropping has changed the microbial community structure of tobacco rhizosphere soil,resulting in changes in the functional structure;The metabolic function of replication and repair in intercropping is weakened,which may involve the reduction of tobacco target spot disease;Salvia miltiorrhiza / tobacco intercropping cultivation model showed obvious intercropping advantages.