Analysis Of Soil Microbial Characteristics And Its Influencing Factors In Tobacco Field

This work analyzed the quantity,diversity,community structureand other relevant indicatorsof the rhizosphere soil microbial in tobacco area of Yiyang County,Luoning County,Ruyang County,and Linying County,Henan Province.The effects of the different ecological factors on the rhizosphere soil microbial communities of tobacco fields were explicated,providing theoretical support for thesoil health maintenance of tobacco fields by biotechnological measures.(1)During the growth of tobacco plants,the characteristics of microbes were as follows: the number of culturable bacteria>actinomycetes>fungi in the rhizosphere soils of plains and hilly regions,and the number of culturable microorganisms increased firstly and then decreased,reaching the maximum value atvigorous growing stage.As the growth of tobacco plants,the diversity of bacterial and fungal communities decreased and the similarity of microbial community structure was higher duringthe vigorous growing and mature stages than before the transplanting.In the plain and hilly regions,the differences of the dominant bacteria species in the rhizosphere soil was minor,but the differences ofthe species and abundance of dominant fungi was more significant.(2)The number of culturable bacteria and actinomycetes in the rhizosphere soil of healthy tobacco fields during long-term and mature periods was much higher than that in non-healthy tobacco fields.The number of culturable fungi in susceptible tobacco fields was higher than that in healthy tobacco fields at maturity,and healthy tobacco field microorganisms were also found.The community diversity is basically larger than that of susceptible tobacco fields,and the bacterial and fungal community structures are quite different at maturity.The relative abundance of beneficial bacteria in the rhizosphere soil of mature tobacco fields is higher than that of susceptible tobacco fields.The pathogenic bacteria in the rhizosphere soil of susceptible tobacco fields were higher than those in healthy tobacco fields.(3)Compared with continuous cropping of tobacco,planting corncould increasethe microbial diversity of rhizosphere soil.There isno significant difference of dominant bacterial species in the level of phylum andgenusin the rhizosphere soil between the tobacco field and the corn field after planting.The dominant fungal species in the level of phylum in the rhizosphere of the tobacco field had no significantly difference with the corn field before planting,but the species and relative abundance inthe level of genus fungi changed significantly after planting.(4)During the growth period of tobacco plants,the number of culturable bacteria and actinomycetes in the rhizosphere soil of rotation crops was larger than that of continuous cropping tobacco fields,but the number of culturable fungi was smaller than that of continuous cropping tobacco fields.The diversity of bacterial and fungal communities in the rhizosphere soil of tobacco rotation fields during the growth of tobacco plants was higher than that of continuous cropping tobacco fields.During vigorous growing period and mature period,themicrobial community structure of rhizosphere soil in the rotation cropping tobacco fields showedremarkable difference with the continuous cropping tobacco fields.The relative abundance of probiotics in rhizospheric soil of rotation field was higher than that of continuous cropping tobacco field,andthe pathogenic of Pythium appeared in the rhizosphere soil of continuous cropping tobacco field.(5)With the increase of continuous cropping years,the number of culturable bacteria and actinomycetes in the rhizosphere soil of tobacco fields gradually decreased,and the number of fungi increased.The microbial community diversity and the relative abundance of probiotics gradually decreased,,and the relative abundance of pathogenic increased.During vigorous growing period,the bacterial community structure was quite different in the rhizosphere of the 2 yearscontinuous croppingtobacco fieldwith the 4 and 6 years ones.There was a difference in the fungal community structure during the continuous cropping years before and after the transplanting.(6)By comparing the microbial flora in the rhizosphere of healthy tobacco fields with non-healthy tobacco fields,it was found that the planting methods,theyears of continuous cropping,and the incidence of tobacco fields had important effects on soil health in tobacco fields.The status of tobacco soilcan be improved by adopting rotation measure,reducing continuous years,and managing fertilization methods.