氮素对拔节期受旱玉米根系发育与产量形成的调控机制研究

In China, soil drought occurred frequently in maize-growing region during jointing stage, which reduced maize yield seriously. Reasonable nitrogen management could improve drought resistance and water use efficiency in maize. The root is the original organ that responding to the change of soil water and nitrogen content, and the root system architecture and root vigor are closely linked to drought resistance in maize. Thus, we will conduct a pot trait with drought sensitive and tolerant genotypes at various nitrogen fertilization regimes and soil drought will set up at jointing stage. The research will be focused on the dynamic of root system architecture, physiological metabolic activity, differential protein expression profiles and gene expression, to investigate the regulatory mechanism of nitrogen rate on root development in water stressed maize. In combination with dynamic of water and nitrogen acquisition, assimilates translocation and yield variance, the research will reveal the relationship between resistance to drought and root development that affected by nitrogen rate in drought tolerant and sensitive maize genotypes. These findings will add the complexity water and nitrogen attainability interaction that determine yield of maize, also will be helped to develop effective techniques to alleviate drought stress in maize cultivation and would be useful in high tolerant maize cultivars screening.

拔节期土壤干旱在我国玉米产区发生频率高，严重影响玉米安全生产，而合理施氮利于玉米抗旱性的提升和水肥资源的高效利用。根系作为响应水肥环境的原初器官，其构型和代谢特性与玉米的抗旱性密切相关。本项目拟选择抗旱性差异玉米品种，在不同施氮量下进行拔节期干旱胁迫，从根系发育入手，对根系“构型的时空变化-生理活性的改变-蛋白和关键基因表达差异”进行剖析研究，逐步深入阐述氮素调控玉米根系发育差异响应干旱胁迫的机制；结合植株养分吸收、同化物运转和籽粒产量的变化，分析并阐明玉米抗旱性获得与根系发育响应氮素的关系，丰富水分和氮素对玉米产量形成的协同机理，为选育耐旱玉米品种和探索抗旱栽培技术提供理论依据。

针对土壤干旱严重影响玉米生产的问题，从合理施氮提升玉米抗旱性和水肥资源利用角度入手，选用抗旱性差异玉米品种，设置氮肥梯度和关键生育期干旱试验，研究氮素对受旱玉米根系形态建成、生理生化特性的调控效应及其与地上部物质生产之间的相关关系，进而阐释氮素调节玉米抗旱性的机制。研究表明：氮素能缓解受旱玉米的产量损失，这与其明显提高玉米气生根的根长、根表面积及其占比显著正相关。通过比较不同氮素水平下抗旱性不同玉米品种根系发育与产量形成对干旱响应的差异发现，较大的浅层节根占比有利于提高玉米抗旱性。生理生化分析表明，氮素能够通过提高渗透调节物质含量、增强抗氧化系统以减少膜脂过氧化，并协调植物激素合成，从而改善其对水分胁迫的适应能力。两个抗旱性不同品种对干旱胁迫和氮素的响应差异主要表现在抗旱品种根系渗透调节物质含量、谷胱甘肽含量，以及内源激素含量变化对干旱和氮素的响应幅度大于干旱敏感品种。研究结果丰富了水分和氮素对玉米产量形成的协同机理，可为选育耐旱玉米品种和探索抗旱栽培技术提供理论依据。