花生根系分泌物的生态效应及其与红壤地区花生连作障碍关系研究

Peanut is an important oil and cash crop in the hilly red soil regions of southern China. Peanut replanted obstacle has been seriously confining the sustainable development of local peanut industry. Peanut can change soil environment by root exudates during its growing period, and the changes of soil environment also influence disease resistance of peanut and its growth. The objectives of this subject therefore were to study ecological effects of peanut root exudates on soil organism and disease resistance of peanut, and explore its relation with peanut replanted obstacle as viewed from soil micro-ecosystem change. Peanut root exudates will be collected in the controlled hydroponics condition and determined using liquid chromatography, and the dynamics of their remaining in the red soil will be observed by simulated experiments. The effects of peanut root exudates on soil microbial and nematode community, peanut root-rot pathogen will be studied using the microcosm culture. The effects of peanut root exudates on resistance of peanut in physiological and biochemical characteristics, defense gene expression to root-rot disease will be studied by potting experiment in greenhouse. The results are, therefore, crucial important to illustrate the mechanism of peanut replanted obstacle, and to develop its control techniques in the red soil regions of southern China.

花生是南方低丘红壤区的主要经济作物和油料作物，长期连作引起的生产障碍已严重制约着当地花生产业的可持续发展。花生在其生长过程中不断通过根系分泌物影响着土壤环境，土壤环境的变化反过来也会影响花生的抗病性能及其生长发育。因此，本项目拟通过室内培养实验收集花生根系分泌物，测定主要成分,并研究其在红壤中存留特性；通过实验室微宇宙培养，研究花生根系分泌物对土壤微生物群落、土壤线虫种群及花生根腐病菌的影响机制；通过盆栽试验研究花生根系分泌物对花生抗根腐病的生理生化活性和防卫基因表达的影响, 以期阐明花生根系分泌物对土壤生物、花生抗病性的影响机制等生态效应，并从根际微生态角度探讨其与花生连作障碍的关系。研究结果对揭示南方红壤区的花生连作障碍机制有重要理论意义，对进一步研发花生连作障碍防治技术具有重要参考价值。

针对南方红壤旱地区花生连作障碍的农业生产问题，从花生根系分泌物组成和土壤生态效应角度，研究了根系分泌物与花生连作障碍的关系。通过项目3年的实施，取得主要结果如下：明确了花生根系分泌物组成是判断花生抗病性能的重要指标，说明花生根系分泌物与连作下花生病害上升有直接关系；证实了花生根系分泌物是连作花生地土壤微生物群落演变的重要推动者，其不断分泌会引起土壤中有关花生病原真菌明显增加，而一些有益菌群如根际促生细菌、菌根真菌显著降低，并且假单胞菌群落组成发生显著变化；揭示了花生根系分泌物中酚酸物质可通过诱导土壤微生物群落变化引起花生生长不良； 明确了花生根系分泌物介导下连作花生土壤微生物群落演变规律，发现连作土壤病原菌的增加是以牺牲土壤有益微生物菌群为代价，恶化了由土壤生物群落（土壤线虫、微生物）生态功能。 发表SCI论文6篇，中文核心论文2篇，培养研究生2名。研究结果为揭示南方红壤区的花生连作障碍机理提供了重要理论依据，对研发花生连作障碍防治技术具有重要参考价值。