Effects of tillage depths and green manure overturning on microbial community structure and diversity of tobacco-planting soil

【Objective】 To study the effects of different tillage depths and different green manures on microbial community characteristics of tobacco-planting soil，to screen out the suitable tillage depths and green manure varieties for the yellow soil tobacco area in Fuquan，Guizhou，so as to provide a theoretical basis for fertilization，soil improvement and ecofriendly high-quality tobacco leaf production in the yellow-soil tobacco region of Guizhou.【Method】 Tobacco-planting rhizosphere soil of 0-20 cm after applying 3 green manure varieties（rape，Vicia villosa，ryegrass）under different tillage depths（shallow tillage and deep tillage） was taken as the research objects，and the non-green manure soil was used as the control.Microbial community structure and diversity of tobacco plant rhizosphere soil were analyzed using Illumina MiSeq high-throughput sequencing technology.【Result】Number of OTUs and endemic bacterial species in rhizosphere soil microorganisms were significantly different，overall it followed a trend of green manure treatment>no green manure control，deep tillage>shallow tillage.Richness and diversity of tobacco-planting rhizosphere soil microbial community in vicia villosa and ryegrass treatments were increased，no significant effect was found in rape treatment，but a significant increase was detected under the treatment of vicia villosa and deep tillage.At the level of phylum，Proteobacteria，Acidobacteria，Actinobacteria，Chloroflexi，were dominant in rhizosphere soil；compared with no green manures treatment，the average abundances of Proteobacteria and Acidobacteria were increased by 0.23% and 4.44%，the Actinomycota and Curvularia were decreased by 1.34% and 1.55%.At the level of genus，the main bacterial genera in the rhizosphere soil of tobacco plants between different treatments were Sphingomonas，Chujaibacter，Rhodanobacter； compared with shallow tillage treatment，the average abundance of Sphingomonas，Chujaibacter，and Rhodanobacter was increased by 0.03%，0.74%，and 0.05%，the unidentified_Gammaproteobacteria，Bryobacter，and Gemmatimonas decreased by 0.37%，0.25%，and 0.16%.Overturning green manure at different tillage depths had a significant effect on the evolutionary branch map of LEfSe，a microorganism grew in tobacco-planting rhizosphere soil.In the different treatments，bacteria with important functions were mainly from class，order and family.In addition to rape and shallow tillage treatment，deep tillage mode worked better to increase dominant microbial community in soil，and under deep tillage modes，among all treatments only Vicia villosa had dominant Bacillaceae at the family level.【Conclusion】Microbial community structure and diversity of rhizosphere soil of tobacco plant are regulated by green manures with different tillage depths.The Vicia villosa and deep tillage is the better，which could be used as an effective cultivation and tillage modein Fuquan Guizhou yellow-soil tobacco growing regions.