不同施氮量和密度下直播油菜根系发育协调产量及茎秆抗倒性机制研究

The stem lodging at maturity stage is not only the key limitation for increasing yield and quality of directly-sown rapeseed, but also the major reason for high yield loss rates resulting in difficulty in promoting mechanized harvesting technology. Previous reports revealed that reasonable nitrogen rate and plant density can both increased stem lodging resistance and yield of rapeseed, well coordinating the contradiction between high yield and high stem lodging resistance. But the mechanism of root development coordinating yield and lodging resistance under different nitrogen rate of rapeseed has been rarely reported. This project using the rapeseed Huayouza 62 and Fengyou 520 as experimental material, setting various nitrogen applications and plant density to create different root architecture, yield and stem lodging, aim to find out the ideal root architecture related to high yield and high stem lodging resistance, finally illustrating the correlation between key indices of ideal root architecture and aboveground growth. Moreover, the researches conducting on physiology, biochemistry, combined with root metabolomics and transcriptomics to deeply study the physiological and molecular mechanisms of ideal root architecture development effects on rapeseed yield and stem lodging resistance. The results will provide a theoretical basis for the establishment of rapeseed populations with high yield and lodging resistance that are suited to machine harvesting, also provide reference related with the establishment of root evaluation system and varieties breeding of high yield and high stem lodging resistance.

成熟期茎秆倒伏不仅是直播油菜产量品质提高的关键限制因素，也是机械收获损失率高进而限制机械化生产水平提高的重要因素。前人研究表明，合理施氮量和种植密度可在提高油菜茎秆抗倒性的同时提高产量，较好地协调倒伏和高产间的矛盾，但其根系关键指标及其生长进程协调油菜地上部产量与抗倒性机理尚不明确。本项目以华油杂62和沣油520为材料，设置不同施氮量和密度水平，构建直播油菜不同根系构型及其对应的成熟期籽粒产量与茎秆抗倒性，明确高产、抗倒油菜的理想根系构型，阐明理想根系构型的关键指标参数和地上部的关联，从生理生化水平结合根系代谢组学和转录组学分析，深入研究根系主要关键指标的动态过程对成熟期产量及茎秆抗倒性影响的生理和分子机制，为油菜高效生产提供理论支撑，为高产抗倒协调的油菜根系评价体系的建立、高产抗倒品种的选育提供参考。

成熟期茎秆倒伏不仅是直播油菜产量品质提高的关键限制因素，也是机械收获损失率高进而限制机械化生产水平提高的重要因素。合理施氮量和种植密度可在提高油菜茎秆抗倒性的同时提高产量，较好地协调倒伏和高产间的矛盾。本研究开展了不同基因型甘蓝型油菜的大田试验与盆栽验证分析试验，我们通过设置不同施氮量和密度水平，构建了直播油菜不同根系构型，及其对应的成熟期籽粒产量与茎秆抗倒性。明确了在施氮量为240 kg.hm-2、种植密度为45万株.hm–2的条件下构建了高产、抗倒油菜的理想根系构型，此时具较大的群体根系表面积和合理的主侧根比，合理的激素含量，具较强的根系活力，促进根系养分的吸收与转运，相应地形成较大的叶面积指数，有利于氮素和干物质累积，优化茎秆成分，协同提高产量和抗倒性。相关分析表明花期是根系影响油菜生产的关键时期，结合生理生化及分子水平分析表明IAA是施氮量和种植密度影响油菜根系生长发育进而影响产量与抗倒性的关键指标参数。转录组分析表明，BnaMYB61、BnaLAC4等是施氮量和种植密度影响直播油菜产量和倒伏的候选基因，它们的表达情况受施氮量和种植密度的调控。鉴于BnaMYB61在减氮增密栽培中的应用潜力，我们分析了不同施氮量和种植密度下茎秆和籽粒中BnaMYB61的表达模式，并创建了突变体进行了功能分析。本研究结果为油菜高效生产提供理论支撑，为高产抗倒品种的选育提供参考。