棉秆炭化还田对新疆连作棉田土壤微生物多样性及黄萎病病原菌影响的研究

The increasingly serious Verticillium wilt disease caused by long-term continuous cropping is one of bottlenecks preventing healthy development of Xinjiang cotton industry. A large number of studies showed that soil-borne diseases were closely related with disbalance of the soil microbial ecology. It was proved that biochar had the characteristics of improved living environment of soil microorganisms, regulated of microbial community structure and functional features, and there were a few reports that biochar had control effects on part of soil-borne diseases. Therefore, combined with previous work, the applicant speculate that the returning of carbonized cotton stalk to field will adjust the soil microbial ecology increase beneficial microorganisms and inhibit Verticillium wilt pathogen (Verticillium dahliae) in continuous cropping cotton field . In this project, experimental material will use biochar from cotton stalk. Soil microbial diversity and Verticillium wilt pathogen in long-term continuous cropping and Verticillium wilt of cotton soil-cotton farming system will be taken as the object of this study. We will focus on the effects of returning of carbonized cotton stalk to field on soil microbial survival environment, structure and functional diversity as well as cotton Verticillium wilt pathogen in long-term continuous cropping by using conventional soil microbial ecology technology and modern methods of molecular biology through 4 years of micro-plot experiment. At the same time, we will explore the relationship and mechanism between soil microbial diversity and Verticillium wilt pathogen by returning of carbonized cotton stalk to field . The results of these studies will provide theoretical basis for controlling cotton soil-borne diseases by soil micro-ecological regulation.

长期连作引起的黄萎病等土传病害日益严重是阻碍新疆棉花产业健康发展的瓶颈之一。大量研究表明，土传病害的发生与土壤微生物生态失衡密切相关。生物质炭具有改善土壤微生物生存环境、调节微生物群落结构和功能等特性，已有少量报道生物质炭对部分作物土传病害有防控作用。结合前期工作，申请人认为棉秆炭化还田可以调节土壤微生物生态，增加有益微生物数量，对黄萎病病原菌的繁殖有一定的抑制作用。本项目以棉秆制备的生物质炭为试材，以长期连作并有黄萎病发生的棉田土壤-棉花种植体系中的土壤微生物多样性和黄萎病病原菌为研究对象，采用土壤微生物常规生态学技术和现代分子生物学方法，通过4年微区定位试验，重点研究棉秆炭输入对长期连作棉田土壤微生物生存环境、结构和功能多样性的影响，及其对棉花黄萎病病原菌的影响，探索棉秆炭化还田对土壤微生物多样性与黄萎病病原菌消长之间关系及机制，为土壤微生态调控防治棉花土传病害提供理论依据。

新疆棉花连作现象很普遍。棉秆就地粉碎还田是目前棉秆利用的主要方式，但带病菌棉秆长期还田导致棉田黄萎病加重，棉秆分解产生的化感物质在土壤中积累的自毒效应也进一步加重了连作障碍。棉秆炭能提升土壤稳定碳库储量、改善土壤理化性质、促进作物生长、消除秸秆上携带的病原菌及通过吸附土壤中化感自毒物质，缓解棉花连作障碍。本项目采用实验室模拟及田间应用相结合的方法，对新疆灰漠土和风沙土连作棉田施用生物炭土壤养分和微生物多样性的变化；棉秆直接粉碎还田和棉秆炭化还田对新疆连作棉花根际土壤微生物数量、群落功能和结构多样性的影响；连作棉田施用棉秆炭土壤微生物多样性与土传黄萎病病原菌数量的关系开展了较为系统的研究，在以下方面取得了重要进展：. （1）研究表明，施用生物炭对新疆灰漠土和风沙土连作棉田根际土壤养分和微生物多样性均有提升作用，且提升效果风沙土好于灰漠土。. （2）采用平板计数法、Biolog碳源利用和PCR-DGGE、高通量测序等分子生物学技术，分析了不同棉秆处理对新疆连作棉田根际土壤微生物数量、群落功能和结构多样性的影响和益生、拮抗等功能特征。微区定位试验证实，高量施用棉秆炭可显著提高棉花根际土壤微生物多样性，并明显增加了土壤细菌种类，增加了土壤中芽单胞菌门、酸杆菌门、变形菌门和放线菌门中一些菌群的丰度。. （3）比较了棉秆移除、棉秆直接粉碎还田和棉秆炭化还田处理连作棉田土壤中黄萎病病原菌数量的消长。结果显示，与棉秆移除和棉秆直接粉碎还田相比，棉秆炭化还田土壤中黄萎病病原菌数量明显下降，虽然没有显著降低棉花黄萎病发病率，但有缓解病害发病程度的趋势。. 综上所述，经过4年的连续施用，与传统的棉秆粉碎还田相比，棉秆炭可显著提高棉花根际土壤微生物多样性，并改变土壤细菌群落结构，降低黄萎病病原菌数量，对连作棉田生态系统健康有改善作用。