茅苍术间作缓解南方红壤地区花生连作障碍的机理

Peanut is an important cash crop in the hilly red soil regions of southern China, and its replanted obstacle has been seriously decreasing the yield and quality of peanut. The earlier results showed that the intercropping with Atractylodes lancea can effectively relieve peanut replanted obstacle. When A. lancea intercropping with peanut, A. lancea can change soil biota community by root exudates during its growing period, and then influence disease resistance of peanut, or directly influence disease resistance of peanut by the special volatile components released from the aerial part of A. lancea. Therefore, root exudates and volatile components released from A. lancea will be collected, and determined using liquid chromatography or gas chromatography-mass spectrometry. The effects of A. lancea root exudates on soil microbial and nematode community, peanut soil-borne pathogens will be studied using 454 high-throughput sequencing, identification of populations and vitro culture respectively. The effects of the root exudates and volatile components from A. lancea on the resistance of peanut in physiological and biochemical characteristics, defense gene expression to soil-borne disease will be studied by pot experiment in greenhouse. Certain compounds of A. lancea that having the main ecological effects of its intercropping will be identified, and the mechanisms of relieving peanut replanted obstacle by intercropped with A. lancea will be verified through field trials. The results are, therefore, crucial important to illustrate the regulating mechanisms of intercropping to peanut replanted obstacle, and to develop its control techniques in the red soil regions of southern China.

花生是红壤地区的主要经济作物，长期连作引起的生产障碍已严重制约着花生生产。近来研究结果表明茅苍术间作能有效缓解花生连作障碍。茅苍术与花生间作，可能通过根系分泌物对土壤生物群落产生影响，进而影响花生生长；也可能直接通过地上特殊挥发油组分对临近花生生理生长产生影响。因此，本项目拟通过收集茅苍术根系分泌物和地上挥发性组分，采用液-质联用、气-质联用等方法测定其主要成分；采用454高通量测序、种群鉴定及离体培养方法，研究其根系分泌物对土壤微生物及主要土传病原菌和土壤线虫的影响；通过测定花生抗性酶活性，并利用荧光定量PCR等方法，研究其根系分泌物和挥发性物质对花生生理抗性、防卫基因表达的影响及机制；探明茅苍术间作生态效应的主要化合物；并通过田间试验验证茅苍术间作缓解花生连作障碍的机理。研究结果对揭示红壤区花生连作障碍的间作调控机理具有重要理论意义，对进一步研发花生连作障碍调控技术具有重要参考。

茅苍术间作可有效缓解南方红壤区花生连作障碍，但具体间作调控机理尚不清楚。本项目从地下和地上途径系统揭示了间作茅苍术缓解花生连作障碍的机制，明确了间作药用植物综合生态效应。项目实施4年来，取得主要结果如下：茅苍术间作显著改善了花生根际微生物区系、线虫群落，提高了花生产量，说明优化根际微生态环境是改善连作花生生长的重要作用途径。扩散培养试验发现茅苍术根茎挥发物可在土壤中扩散，优化连作花生土壤真菌群落组成，但对细菌群落影响较小；进一步离体培育实验揭示出根茎挥发物对花生根腐病菌有显著的直接抑制作用，利用GC/MS鉴定出萜类物质是茅苍术块茎挥发物抑制病原菌的主要成分。而茅苍术根系分泌物对连作花生主要病原菌并无明显抑制作用。 花生/茅苍术根部隔开仅地上进行互作的间作方式提升了花生抗病相关酶活，表明茅苍术地上部可产生挥发性化感物质诱导花生生理反应，这种反应进一步导致花生根系分泌特征的变化，改善了根际微生态抗性，进而降低土传病害发生；同时应用顶空固相微萃取-GC/MS鉴定多种烯类化合物是提升花生抗性的主要功能物质。项目研究发表了SCI论文8篇（一区TOP论文3篇），中文核心论文3篇，培养2名研究生毕业，部分内容参与成果集成获省科技进步二等奖1项。研究结果探索出植物与植物、植物与土壤微生物、土壤微生物之间等作用方式缓解连作障碍的机制，对推到我国连作障碍调控研究具有重要理论意义，也为攻克连作障碍难题提供了新的思路。