轮作对香蕉土壤线虫群落组成及多样性的影响

With growing demand and increasing land-use pressure, the soils used to grow banana in China are not as productive as they could be. Continuous banana cropping has been a common practice in the tropical region of China. Continuous cropping involves the build up of soil-borne pathogens such as plant parasitic nematodes, which has seriously affected the healthy development of the banana industry in China. Rotation is one of effective methods to control of plant parasitic nematodes. Reasonable rotation can maintain farmland ecosystem balance, increasing soil nematode diversity, promoting soil organic matter decomposition and nutrients mineralization and other ecological processes. Economic benefit and ecological benefit are also significantly improved in banana rotation planting areas. The project is conducted at long-term banana continuous cropping and rotation experimental site, Chinese Academy of Tropical Agricultural Sciences, Hainan, China. The project studies the temporal and spatial variation characteristics of soil nematode community and diversity in banana plantation under continuous cropping and rotation systems, using nematode morphology classification and PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) molecular biology techniques. The purpose of this study is to compare the relationships between soil nematode community structure and soil physicochemical properties and soil biological activity characteristics under continuous cropping and rotation systems, investigating the effects of continuous cropping and rotation on soil ecological indicators of banana plantation, revealing the reasons of rotation to control banana plant parasitic nematodes disease and establishing soil nematode DNA fingerprint analysis method under different banana cropping systems. We expect this study can provide theoretical basis for the application of rotation to control plant parasitic nematodes in Chinese banana planting areas.

由于耕地有限，需求量不断增长，香蕉都是以大面积连作为主。随着连作年限不断增加，香蕉产区的植物寄生线虫病害逐年加重，已经严重影响了我国香蕉产业的健康发展。轮作是防治植物寄生线虫病害的有效方法之一，合理轮作能够维持农田生态系统的平衡，增加土壤线虫的生物多样性，促进土壤有机质分解和养分矿化等生态过程，显著提高香蕉产区的经济效益和生态效益。本项目采用线虫形态学分类和PCR-DGGE(聚合酶链式反应-变性梯度凝胶电泳)分子生物学技术相结合的方法，开展连作和轮作条件下香蕉产区土壤线虫群落组成和多样性的时空变化特征研究。通过比较连作和轮作条件下香蕉产区的土壤线虫群落结构和土壤生物活性与土壤理化性质之间的相互关系，探讨连作和轮作对蕉园土壤生态因子的影响，揭示轮作防治香蕉植物寄生线虫病害的原因，并建立连作和轮作条件下香蕉产区土壤线虫DNA指纹分析方法，为推广应用轮作措施防治香蕉植物寄生线虫病害提供理论依据。

由于耕地有限，需求量不断增长，香蕉都是以大面积连作为主。随着连作年限增加，香蕉产区的植物寄生线虫病害逐年加重，已经严重影响了我国香蕉产业的健康发展。轮作是防治植物寄生线虫病害的有效方法之一，合理轮作能够维持农田生态系统的平衡，增加土壤线虫的生物多样性，促进土壤有机质分解和养分矿化等生态过程，显著提高香蕉产区的经济效益和生态效益。本项目采用线虫形态学分类和PCR-DGGE(聚合酶链式反应-变性梯度凝胶电泳)分子生物学技术相结合的方法，开展连作和轮作条件下香蕉产区土壤线虫群落组成和多样性的时空变化特征研究。通过比较连作和轮作条件下香蕉产区的土壤线虫群落结构与土壤理化性质之间的相互关系，探讨连作和轮作对蕉园土壤生态因子的影响，揭示轮作防治香蕉植物寄生线虫病害的原因，并建立连作和轮作条件下香蕉产区土壤线虫DNA指纹分析方法，为推广应用轮作措施防治香蕉植物寄生线虫病害提供理论依据。.研究结果表明，不同土层深度轮作和连作蕉园共发现土壤线虫49-53属。香蕉-菠萝、香蕉-番木瓜和香蕉-水稻轮作区的土壤线虫总数、食细菌线虫数量、捕食/杂食线虫的数量、多样性指数(H‘)、自由生活线虫成熟度指数(MI)、结构指数(SI)和富集指数(EI)指数显著高于香蕉连作(P < 0.01)，而植物寄生线虫数量、优势度指数(λ)和植物寄生线虫成熟度指数(PPI)显著低于香蕉连作区(P < 0.01)；随着土层深度的增加，土壤线虫总数、食真菌线虫数量、植物寄生线虫数量、H’、λ、PPI和EI指数显著降低(P < 0.01)，捕食/杂食线虫数量、MI和SI指数显著增加(P < 0.01)。本研究显示，土壤线虫群落结构可有效反映轮作和连作蕉园土壤的健康状况，土壤线虫可作为土壤中重要的指示生物。.研究发现，通过PCR-DGGE与形态分类方法得到线虫多样性信息的变化趋势基本一致，且相对于形态学方法，PCR-DGGE方法得到的多样性指数能够比较迅速地反映线虫多样性的变化，具有较高的灵敏度。PCR-DGGE结果的聚类分析能够直观地反映线虫群落结构的变化。PCR-DGGE方法能够在优化样品量和提取方法的条件下获得更多的种属信息，且凝胶条带的峰强度能够反映出该条带基因测序后所对应种属的丰富度，是揭示轮作和连作条件下土壤线虫多样性变化的有效工具。