玉米根系对局部供磷和相邻作物根系的协同响应及根际调控机制

Plant roots exhibit high morphological and physiological plasticity in response to nutrient heterogeneity in order to exploit nutrient resources effectively. Root proliferation and rhizosphere acidification can be enhanced by localized nutrient supply in nutrient-rich patches, resulting in improved nutrient use efficiency. The root proliferation in nutrient-rich patches can be significantly affected by root interactions of neighbors. However, how the plant roots co-respond and integrate the information from heterogeneous nutrient resources and neighbors is largely unknown, which is a key question related to efficient capture and use of heterogeneous nutrient resources in intensive farming system for maize (Zea mays L.). Based on a series of rhizobox experiments and field trials, the present study focuses on synergistic responses of maize roots to localized P supply and neighbors and their rhizosphere regulation mechanisms of P efficient use. The studies are conducted by using new methods or techniques such as in situ monitoring rhizosphere processes, localized nutrient supply control technique, visualization of pH changes in the rhizosphere, probe of fluorescence dye technique for NO and phosphatase and molecular biological techniques. The main objectives in the studies are to investigate the effects of homogeneous and heterogeneous P supply intensity on root interactions of maize and neighbor and their spatio-temporal distribution, examine the synergistic responses of maize roots to localized P supply and neighbors and their contribution to improved P uptake, reveal the processes of root-root interactions of maize roots and neighbor under the conditions of localized P supply and the regulation mechanisms of rhizosphere processes, and establish the technique pathway of rhizosphere/root zone management for improving P use efficiency for intensive maize cropping system. This study will provide important scientific bases to uncover the mechanism of efficient use of heterogeneous nutrient resources by maize at presence of root competition of neighbor in cropping system, and thus improve heterogeneous P use efficiency for sustainable maize production.

植物根系对异质性养分供应具有高度的形态与生理可塑性。局部养分富集显著刺激根系增生和根际酸化，提高了养分吸收效率。根系对局部养分的响应受相邻植物竞争的强烈作用，但植物根系对局部供磷和相邻植物的协同响应及其调控机制并不清楚。这是深入揭示集约化条件下玉米根系对局部养分资源高效利用的关键问题。本研究通过根箱模拟和大田试验，以玉米根系对局部供磷和相邻植物的协同响应及根际调控机制为主线，采用根际原位监测、局部养分控制、pH荧光探针检测结合分子生物学手段等方法，研究整体和局部供磷强度对玉米和相邻植物根系互作与时空分布的影响，探讨玉米根系对局部供磷和相邻植物根系的协同响应及对磷吸收的贡献，揭示局部供磷条件下玉米和相邻植物的根系互作过程及根际调控机制，提出农田磷高效利用的根际调控途径。为揭示集约化种植条件下玉米对异质性养分资源高效利用机制，通过根际调控提高磷资源的利用效率，实现作物可持续生产提供科学依据。

植物根系对异质性养分供应具有高度的形态与生理可塑性。局部养分富集显著刺激根系增生和根际酸化，提高了养分吸收效率。根系对局部养分的响应受相邻植物竞争的强烈作用，但植物根系对局部供磷和相邻植物的协同响应及其调控机制并不清楚。本研究采用根际原位监测、局部养分控制、荧光探针检测等方法，系统探讨了玉米根系对局部供磷和相邻植物的协同响应及根际调控机制，主要进展包括：（1）揭示了整体和局部供磷强度对玉米和相邻植物根系互作与时空分布的影响，发现局部养分供应与玉米根系生长的时空耦合影响群体竞争与产量；（2）阐明玉米根系对局部供磷和相邻植物根系的协同响应，发现局部供磷刺激玉米根系增生，促进玉米/蚕豆体系中玉米对局部养分的利用；（3）明确了局部供磷条件下玉米和相邻植物的根系互作过程及根际调控机制，发现局部供磷显著影响玉米与相邻植物的根际互作效应，揭示了玉米/豆科作物间作高效获取土壤磷的根际互补策略与机制，首次揭示相邻植物通过根际互作修饰玉米根系觅食行为的新机制；（4）揭示了一氧化氮和糖介导局部供磷调控玉米根系增生的分子生理机制，发现侧根原基生长素积累与一级侧根细胞活性增强是局部供磷诱导侧根增生的主要机制，一氧化氮和糖在调控局部供磷促进玉米根系增生中起到关键信号作用；（5）揭示了作物对局部供磷的响应及其高效利用的根际效应机制，阐明了玉米根系时空分布与磷资源分配的协同关系；（6）建立了农田土壤异质性磷高效利用的根际养分调控途径。在主流期刊发表论文26篇，其中在Trends in Plant Science、New Phytologist、Functional Ecology、Plant and Soil 等发表SCI论文21篇，有14篇IF>5，第一标注的SCI 文章8篇；作大会特邀报告3次，分组报告4次；培养博士后3人；培养研究生10名（博士4人，硕士6人）。研究成果为揭示集约化种植条件下玉米对异质性养分资源高效利用机制，通过根际调控提高磷资源的利用效率，实现作物可持续生产提供了科学依据。