豆科//禾本科促进豆科作物结瘤固氮是形成间作产量优势的重要保证。长期以来，对豆科//禾本科系统的研究主要集中在地上部光热资源利用、养分吸收、病害控制等方面，对地下部种间互作影响豆科作物结瘤固氮的研究较少。最近研究表明，豆科//禾本科系统根系分泌物中黄酮类物质在豆科作物结瘤中发挥重要作用，但有关间作系统氮素施用对黄酮类物质分泌的影响及其在豆科作物结瘤固氮中的作用机理还未见报道。本项目以小麦//蚕豆为对象，利用大田试验、砂培、琼脂培养方法和根瘤菌接种手段研究：（1）氮素对小麦//蚕豆系统蚕豆结瘤的影响；（2）氮素对小麦//蚕豆系统根分泌黄酮类物质的影响；（3）黄酮类根分泌物影响豆科作物结瘤固氮的机理；（4）豆科//禾本科系统氮素影响生产力的地下部氮素-根系黄酮类物质分泌-结瘤固氮的互作机制。开展本研究对阐明豆科//禾本科提高作物养分利用效率、农田生态系统生产力和稳定性具有重要的理论和现实意义。

Facilitation of legume crop nodulation and symbiotic N2 fixation in Legume//cereal is the main basis of intercropping yield advantage. It has been paid much attention on the investigation of light and heat resource use efficiency, nutrient uptake and diseases control in Legume//cereal system, but few researches have been focused on the relationship of rhizosphere processes with legume crop nodulation. Recent studies showed that, flavonoids in root exudates play an important role in legumes crop nodulation, but little information is known about the effects of nitrogen on root exudation of flavonoids and its role in nodulation and nitrogen fixation of legumes crop in legume//cereal system. Field trials, sand/agar cultures and rhizobium inoculation method for wheat//faba bean system will be implemented in this study, the objectives are to investigate: (1) Effects of nitrogen application on faba bean root nodulation in wheat//faba bean system; (2) Effects of nitrogen application on root exudation of flavonoids in wheat//faba bean system; (3) Mechanisms of flavonoids root exudates on faba bean nodulation and nitrogen fixation; (4) Mechanism of interactions among nitrogen - root exudation of flavonoids - faba bean nodulation and nitrogen fixation. Implementation of this research is of scientific and practical importance not only for comprehensive understand the reality of yield advantages, but also for elucidate the improvement of nutrient use efficiency, productivity and stability of field ecosystem in legume and cereal intercropping.