不同水氮处理对麦田土壤微生物区系的影响及其调控机制

Water and nutrient uptake of crop depends on root system, and its absorptive ability directly determines crop growth and development and yield formation. Soil microbes are important biological components of soil, as they play a key role in soil physiological processes, including the decomposition of organic matter, the nutrient cycling, the promotion or depression. Soil microbes affect soil fertility for agriculture, via the rate of decomposition of organic material. Therefore, soil microbes can be used as biological indicators of soil fertility and health. This study aimed at assessing the effects of water-nitrogen interaction experimental combination on soil microbial community composition, enzyme activities. It is important for optaimal regulaiton of water and nutrient of winter wheat.The main grain crop–winter wheat of the Huang-Huai-Hai Plain is choosen as study object, and a combination method of rhizo-box experiment and field trial adopt. The main contents of the project are as follows: (1) Relationship of root characteristics (root morphological traits, root activity and root exudates)with soil microbial flora(soil microbial community composition, enzyme activities) under water and nitrogen (2) Regulation mechanism of water and nitrogen on soil microbial flora;(3)Effects of soil microbial flora under water and nitrogen on water and fertilizer use efficiency of winter wheat.Results would be useful for improving water and nitrogen use efficiency and regulation high efficiency management practices of soil microbial flora of winter wheat under water-nitrogen interaction. It’s significant for maintaining soil ecological balance and increasing agricultural productivity.

根系对水分和养分的吸收能力直接决定着植株的生长发育和产量的形成。土壤微生物对土壤中养分的转化循环吸收转运和对逆境抗性的提高有重要作用，可以作为土壤肥力和土壤健康的生物学指标。研究水氮互作对麦田土壤微生物区系特征的影响，对于冬小麦水氮最优调控具有积极的意义。本项目以黄淮海平原主要农作物-冬小麦为研究对象，采用根箱试验和田间试验相结合的研究方法，主要研究内容包括：（1）不同水氮处理下冬小麦根系特征对土壤微生物区系特征的影响；（2）不同水氮处理对冬小麦土壤微生物区系的影响及调控；（3）不同水氮处理下土壤微生物区系对冬小麦水肥利用效率的影响。研究对于通过高效水肥管理措施调控土壤微生物区系，对维护土壤生态平衡和提高农业生产力有重要的指导意义。

合理的灌溉施肥制度有助于提高冬小麦水分和养分利用和产量的增加潜力。本项目以高产冬小麦品种‘百农207’为供试材料，设置不同水分和氮素进行田间和室内试验，利用生理生化研究方法和借助于高通量测序方法研究了不同水氮处理下的冬小麦根系发育特性、根际土壤微生物区域特征。揭示了水氮互作对冬小麦根系生长发育特性、根际土壤微生物群落多样性以及水分利用效率的调控效应。取得以下研究进展：（1）水分是决定次年小麦种子活力指数、种子贮藏物质转运率和转化效率的主要因子；氮素是决定次年种子发芽阶段根冠比的主要因子；（2）不同水氮处理下的根际土壤细菌门水平上，放线菌门、变形菌门、酸酐菌门、绿湾菌门、厚壁菌门五个种群为本研究中的根际土壤微生物中的优势种群。水氮对根际土壤微生物细菌物种丰度存在互作效应，不同水氮处理对土壤细菌群落组成及细菌物种丰度影响差异较大。低氮（N0、N120）处理下一定量的灌水会促进多样性指数增加，而物种的优势度差异不大；在中氮（N180）条件下，不灌水或者灌水过多均会降低多样性指数；在高氮（N240）条件下，灌水会促进多样性指数增加，中氮和高氮条件下，灌水会降低物种的优势度。（3）冬小麦根系的生长发育与土壤环境密切相关，水分和氮素通过影响土壤的物理化学特性，改变土壤PH、湿度、温度等，土壤环境的变化影响土壤呼吸、土壤酶活性和土壤细菌群落结构组成的不同，影响根系的生长发育，最终影响冬小麦的产量和水分利用效率。研究结果可为指导农作生产中优化灌溉施肥制度的发展提供理论依据和技术支撑。