玉米和紫花苜蓿作为东北农牧交错区重要粮食作物和优良豆科牧草，两者间作对兼顾区域粮食安全和生态环境改善具有重要意义。磷是限制作物生长发育和产量的重要营养元素，在土壤中有效性低，但间作作物可通过根系构型生态位互补、菌根侵染与根际活化互利来实现间作体系磷素的高效利用，而这些根系形态和生理变化都与根系周转密切相连，但其耦合作用如何促进磷素高效利用的地下过程机理尚不清楚。本研究通过田间试验和盆栽试验，采用同位素示踪技术、根系分隔技术和根系原位扫描技术，综合运用生态学、农学及生理学知识，试图揭示玉米/紫花苜蓿间作根系周转与根系构型和菌根侵染之间互作机理，阐明上述地下过程与磷素高效利用的关系。本研究从根系周转—土壤养分释放—根系吸收的新视角刻画玉米/紫花苜蓿间作提高磷素利用效率的机理，在学术思想上具有创新性。预期成果有望为玉米/紫花苜蓿间作体系精细调控磷肥、减少磷肥投入和降低环境风险提供科学理论依据。

Maize and alfalfa, as the important food crop and the excellent leguminous forb, respectively, have been prioritized in the development of the northeast farming and pastoral area, and their intercropping system has promising prospects. It is probable that belowground processes including water and phosphorus capture are important elements of the productivity of this polyculture. However, the mechanisms of root interactions in polyculture systems are poorly understood. The proposed project would integrate field and greenhouse experiments, isotope tracer methods, root separation methods, and in-situ root scanning methods to explore the relationship between root architecture, rhizosphere mycorrhizal infection and root turnover in different maize/alfalfa intercropping modes, clarify the relationships between these parameters with the absorption and utilization of water and phosphorus of intercropped crops. The study will provide theoretical basis for delicately regulating phosphorus fertilizer utilization in maize/alfalfa intercropping system and reducing its input and risks to the environment.