小麦蚕豆间作根际红壤磷活化及其对（无机）磷施用的响应机制

合理间作能提高土壤磷的有效性、促进作物磷的吸收利用，但合理间作提高土壤磷有效性的机制了解不多，尤其在红壤条件下的作用机制尚不清楚。前期研究中发现，小麦蚕豆间作可以提高红壤根际磷有效性、改变根系低分子量有机酸的分泌、促进作物对磷的吸收利用，且这种效应与肥料施用量有关。但间作根系有机酸的分泌与根际红壤磷有效性之间的关系如何并不清楚，尤其是不同磷水平下，间作改变根际红壤磷有效性的机制如何，尚不明确。因此，本项目主要探讨小麦蚕豆间作条件下：（1）不同无机磷用量下，间作作物根际红壤有效磷含量、无机磷组分变化和根系有机酸分泌特征；（2）不同无机磷用量与间作作物根系有机酸的分泌、无机磷组分变化、根际红壤有效磷活化的响应机制。研究可阐明间作条件下无机磷供应-根系低分子量有机酸分泌-红壤磷活化的互作机制，对深入认识间作提高养分资源利用效率，科学施肥提高产量和农田生态系统生产力具有重要理论和实践价值。

It is well documented that rational intercropping could improve soil phosphorus availability and enhance P acquisition. However, little is known about the mechanism, especially on red soil. In the previous studies we found that wheat and faba bean intercropping improved red soil phosphorus availability and increased organic acids exuded by roots, and also increased P uptake by crops. In addition, the intercropping effect was related to the amount of phosphorus fertilizer applied. Whereas, the relationship between organic acids exuded by roots in intercropping system and rhizosphere phosphorus availability on red soil is still unclear. Especially in the condition of different P levels, the mechanism of intercropping changed rhizosphere phosphorus availability on red soil is remaining unknown. Therefore, based on the former researches, the study will mainly discuss in wheat and faba bean intercropping system:(1) under the condition of different rates of inorganic P fertilizer applied on red soil, the characteristics of rhizosphere available phosphorus content, inorganic phosphorus fraction of red soil and low molecule organic acids exuded by roots; (2) the reaction mechanism among different rates of inorganic P fertilizer applied, organic acids exuded by roots in intercropping system, changing of inorganic phosphorus fraction and mobilization of rizhosphere phosphorus. The study will determine the inter-mechanism among inorganic P applied-organic acids exuded by roots- P mobilization of red soil in intercropping system. The research will have important role on theoretically and practice value for people deeply understands the mechanism of intercropping could improve resources use efficiency, and scientific fertilization is important for increaseing crop yield and farmland ecosystem productivity.