长期稻-稻-绿肥轮作对水稻根际微生物多样性及功能群落的影响

大量研究证实，绿肥是保持和提高土壤肥力和质量的有效措施之一，虽然已有绿肥对土壤微生物影响的相关研究报道，但由于方法和技术所限，相关研究不够系统深入，特别是绿肥对水稻根际微生物影响的研究尚属空白。本课题拟以湖南祁阳农田系统国家野外科学观测研究站具有30年长期定位历史的稻-稻-绿肥（豆科植物紫云英、禾本科植物黑麦草和十字花科植物油菜）及稻-稻-冬闲轮作水稻系统为材料，采用基于16S rRNA、nifH、amoA等基因为基础的先进的分子生态学方法与传统的培养方法相结合，深入研究不同绿肥轮作水稻根际微生物的多样性、氮循环重要的微生物类群（固氮和氨氧化微生物）组成，及其对一些功能性微生物的影响；同时针对性地分离培养微生物类群。研究结果可为长期轮作绿肥对水稻产量的影响提供理论依据，并有利于揭示微生物与植物的相互作用关系，同时将获得提高水稻产量的有益微生物资源。

The application of green manures to rice field is a traditional agricultural practice in China, especially in southern-central part of China. It has been demonstrated that the green manure can increase sustainability of soil eco-system by reducing soil erosion, ameliorating soil physical properties and promote soil fertility; it plays an important role in improving rice yield and maintaining the stability of soil eco-system. However, the effects of green manure on microbial diversity and functional communities in the rhizosphere of succession crops are still not investigated extensively and systematically and our knowledge on the mechanism of effects is still very limited so far. This project will focus on the studies of the effects of long-term winter-growing green manure plants on microbial diversity and nitrogen-cycle related functional communities (e.g.: nitrogen-fixing bacteria and ammonia oxidation microbes) in the rhizosphere of rice based on a 30-year long-term experiments in the Key Field Monitoring Experimental Station for Red Soil Eco-environment of Ministry of Agriculture, Qiyang County of Hunan Province. Four treatments will be setup as rice-rice-winter fallow, rice-rice-Chinese milk vetch, rice-rice-rape and rice-rice-ryegrass and these three different kinds of plants will be used as the three types of green-manure applied commonly in the rice field: Leguminosae, Cruciferae and Gramineae. To look into the effects of long-term rice-rice-green manure rotation on microbial diversity and function communities in the rhizosphere of rice, Culture-independent methods based on the analysis of 16S rRNA, nifH, amoA and amoB genes and traditional Culture-dependent methods will be used cooperatively in this study. Phylogenetics of cultured bacteria by using the method of polyphasic taxonomy; characteristics of cultured strains by testing the production of IAA, phosphate-dissolving ability, nitrogen-fixing and ammonia-oxidizing will be investigated as well. The results of this project will be important for us to better understand the functions of green manure and its effects on the interactions between microorganisms and rice plant. It will be very helpful for us to achieve some rice growth-promotion related microbial resources.