土壤厌氧消毒对青枯病的控制及土壤细菌群落结构的影响

Effects of Anaerobic Soil Disinfestation on Bacterial Wilt and Soil Bacterial Community

近年来,土壤厌氧消毒(Anaerobic soil disinfestation,ASD)作为一种非化学、环境友好型土壤消毒方法,在缓解连作障碍和防治土传病害方面具有显著效果,但其作用机理尚不完全清楚。本研究设置6个处理,即对照、添加米糠(DRB)、麦麸(DWB)、茶麸(DTB)、秸秆(DRS)和不添加物料(D)5种土壤厌氧消毒处理,分析不同处理对青枯病防控效果、土壤理化性质及土壤细菌群落结构组成及多样性的影响。结果表明,与CK相比,添加4种物料厌氧消毒处理对青枯病的防效均达100%,单纯厌氧处理防效为83.3%,且除了DRB外各厌氧处理均能大幅度促进番茄生长。各ASD能显著提高土壤温度、p H和电导率,降低Eh和土壤青枯菌数量。田间试验表明,与CK相比,ASD的番茄青枯病发病率降低29.4%~42.7%,产量增加2.5倍~4.7倍。利用16S r DNA对土壤测序表明,ASD降低了土壤细菌α多样性指数,不同处理间土壤细菌物种种类、丰富度及多样性均存在显著差异。添加不同有机物料的ASD厚壁菌门(Firmicutes)相对丰度大幅度提高,成为优势群落;该门中的厌氧型细菌梭菌科(Clostridiaceae)、瘤胃菌科(Ruminococcaceae)和耐受性细菌芽孢杆菌科(Bacillaceae)等相对丰度也大幅度提高。本研究表明,土壤厌氧消毒处理显著改变了土壤细菌群落结构组成及多样性,厌氧和耐受型细菌丰度大幅度增加,这可能是ASD防控土传病害青枯病的作用机理之一。

【Objective】Anaerobic soil disinfestation（ASD） has been proven to be a promising nonchemical environment-friendly method to control soil-borne diseases,plant parasitic nematodes and weeds,especially in horticulture.However,it is still not so clear about mechanisms of the effects.In this study,both pot and field experiments were conducted to study the effects of ASD on tomato bacterial wilt（a kind of soil-borne disease）,structure and diversity of soil microbial community,soil properties and crop growth,in an attempt to elucidate mechanisms of ASD controlling soil-borne diseases and improving soil health.【Method】The pot experiment was designed to have five treatments anaerobically disinfected,i.e.Treatment DRB（addition of rice bran）,Treatment DWB（addition of wheat bran）,Treatment DTB（addition of tea seed bran）,Treatment DRS（addition of straw） and Treatment D（addition of none）,and one control（CK）; and the field experiment had only four treatments,i.e.,DRB,DWB,DTB and CK.Effects of the treatments on incidence of wilt,amount of the pathogen,crop growth,soil physiochemical properties（soil p H,Eh,temperature,conductivity） were analyzed.Furthermore,16 SrDNA gene（V3＋V4 region） sequencing was done to analyze the composition of soil bacterial community relative to treatment.【Result】Results show that compared with CK,ASD inhibited bacterial wilt by 100% in all the four treatments added with organic material,and by 83.3% in Treatment D.All the treatments,except for Treatment DRB,significantly promoted tomato growth.ASD significantly increased soil temperature,soil p H and conductivity,but reduced soil Eh and decreased the population of Ralstonia solanacearum in the soil by 97.3% ~ 99.1%.Compared with CK,ASD reduced incidence of the disease by 29.4% ~ 42.7% and increased yield of the crop by2.5~4.7 times.Sequencing of 16 S r DNA gene shows that CK and Treatments D and DRB were higher than Treatments DWB,DTB and DRS in bacterial diversity（Shannon index,Simpson index,ACE and Chao 1 index）.Principal component analysis and cluster analysis show that the treatments varied sharply in species,abundance and diversity of soil bacteria community.Treatments DWB,DTB and DRS were lower in relative abundance of Crenarchaeota,Acidobacteria,Actinobacteria,Chloroflexi,Gemmatimonadetes and Proteobacteria in treatments were reduced compared with CK and Treatments D and DRB,but significantly higher in Firmicutes（mostly anaerobic bacteria）,which became the dominant species in the soil bacterial community in Treatments DRB,DWB,DTB and DRS.Besides,ASD significantly decreased the relative abundance of Burkholderiaceae and Ralstonia.【Conclusion】ASD is an effective approach to control soilborne bacterial wilt,and improve soil quality and crop productivity.ASD coupled with addition of organic materials significantly changed the soil bacterial community in structure,composition and diversity,and significantly increased the abundance of anaerobic and anaerobically tolerant bacteria,which may be one of the mechanisms of ASD preventing and controlling bacterial wilt.