淹水对辣椒连作土壤化学性质与微生物群落结构的影响

【目的】 明确淹水对连作辣椒土壤环境的影响,为减轻辣椒连作障碍提供技术依据。【方法】 以安徽和县的大棚内连作辣椒进行连续3年的淹水和不淹水土壤为研究对象,以不淹水为对照,采用流动分析仪、qPCR荧光定量技术和Miseq测序技术探究淹水对辣椒连作土壤化学性质和微生物群落结构的影响;同时以辣椒为试材,采用体外培养皿法验证淹水和不淹水土壤对辣椒种子萌发和幼苗生长的影响。【结果】 土壤淹水处理显著降低了土壤EC值、有机质、硝态氮、铵态氮、速效钾和有效磷的含量。荧光定量结果表明土壤淹水处理显著增加了细菌菌群丰度（P<0.05）,但降低了真菌菌群丰度。高通量测序结果表明,微生物群落组成在门水平上,淹水处理显著增加了放线菌门（Actinobacteria）和Myxococcota的相对丰度,降低了厚壁菌门（Firmicutes）和被孢霉门（Mortierellomycota）的相对丰度;在属水平上,淹水处理降低了潜在病原菌镰孢菌属（Fusarium）相对丰度并与土壤硝态氮呈显著正相关,增加了潜在固氮菌属中的固氮弧菌属（Azoarcus）、芽单胞菌属（Gemmatimonas）、Sideroxydans、Candidatus_Solibacter、藓杆菌属（Bryobacter）及潜在有益菌属Aspergillus和枝顶孢霉属（Acremonium）的相对丰度,并与土壤硝态氮呈显著负相关;土壤硝态氮含量显著影响土壤细菌和真菌的群落结构。培养皿试验结果表明,淹水处理土壤中的辣椒种子发芽率、幼苗鲜重和根长显著高于不淹水处理土壤。【结论】 辣椒连作土壤淹水处理显著降低了EC值,降低了潜在病原菌和增加了潜在有益菌丰度,但土壤速效养分含量显著降低。同时,土壤淹水有利于辣椒种子萌发与幼苗生长,有利于缓解辣椒连作障碍。

Effects of Flooding on Soil Chemical Properties and Microbial Community Composition on Farmland of Continuous Cropped Pepper

【Objective】This paper aimed to clarify the effect of farmland flooding on the soil environment of continuous pepper cropping, and to provide the technical basis for reducing the soil sickness caused by continuous pepper cropping. 【Method】In this experiment, the flooded and non-flooded soil of continuous cropped pepper in Hexian County of Anhui Province were analyzed, with non-flooded soil as control. The determination of chemical property and microbial community structure in soil with flowing analyser, qPCRand Illumina MiSeq sequencing explored the effect of flooding on the soil. Besides, the pepper was used as plant material to explore the effects of flooded and non-flooded soil on seed germination and seedling growth by the Petri dish method. 【Result】Soil flooding significantly decreased the soil EC value, organic matter, nitrate N, ammonium N, available K, and Olsen P. Quantitative PCR analysis showed that soil flooding significantly increased the bacterial community abundance (P<0.05), however decreased that of the fungal communities. Illumina MiSeq sequencing showed that the soil flooding significantly increased the relative abundances of Actinobacteria and Myxococcota, which decreased the Firmicutes and Mortierellomycota at phylum level. The soil flooding decreased the relative abundance of potential pathogenic fungi, such as Fusarium spp., positive correlation with nitrate N. The soil flooding increased potential Azotobacter, including Azoarcus, Gemmatimonas, Sideroxydans, Candidatus_Solibacter, Bryobacter, Sideroxydans spp. and plant-beneficial potential such as Aspergillus and Acremonium spp., which were negatively correlated with nitrate N. The soil microbial community structure and composition was significantly affected by soil nitrate N. In petri dish, the seed germination rate, seeding fresh weight and root length of peppers planted in flooded soil were significantly higher than those in non-flooded soil. 【Conclusion】Soil flooding significantly reduced the EC value and abundance of potentially pathogenic microbial community and increased the abundance of potentially beneficial bacterial, but significantly reduced the content of available nutrients. At the same time, Soil flooding was conducive to the seed germination and seedling growth and alleviated the pepper continuous cropping obstacles.