施氮量对苗期受渍油菜根系发育与产量形成的调节机制研究

Waterlogging is one of the important factors that limiting rapeseed production in Yangtze River. Reducing the yield loss by improving resistance to waterlogging is of great importance to obtaining stable and high yield and efficient production in rapeseed. Reasonable nitrogen management is an important cultivation measure to improve resistance to waterlogging in rapeseed. The root is the original organ that causes physiological and biochemical dysfunction after waterlogging. Its growth and metabolism directly influences crop yield. In the present study, waterlogging was set up at seedling stage under four nitrogen rates with two cultivars. Based on the relationship between root development and yield formation, this research will focus its study on dynamic changes of soil nutrients, antioxidant system and hormone and their correlations with the root system configuration. The key period that nitrogen regulating root development will be then identified. In combination with differential protein expression profiles and gene expressions, this research will well elucidate the regulating mechanisms that nitrogen rates affect root growth and yield of waterlogged rapeseed at seedling stage, and also help to develop effective techniques to alleviate adverse impact by waterlogging and will be useful in waterlogging-tolerant rapeseed screening.

渍害是长江流域油菜高效生产的重要限制因子之一，提高油菜耐渍性，降低产量损失，对我国油菜高产稳产高效生产具有积极意义，而合理的氮肥运筹是提高油菜耐渍性的重要栽培措施。根系是渍水胁迫引起油菜各种生理和生化功能紊乱的原初器官，其生长及代谢直接影响作物生长发育与产量形成。因此，本项目拟以耐渍性差异显著的2个油菜品种为材料，在不同施氮量下进行苗期渍水胁迫，从“根系生长发育-产量形成”的关系出发，重点研究土壤养分、根系抗氧化系统、激素含量动态变化与根系构型和建成的关系，筛选氮素调控苗期受渍油菜根系发育的关键时期，结合该时期根系蛋白质表达图谱及关键编码基因的差异，深入研究并阐明施氮量对苗期受渍油菜根系发育与产量形成的调节机制，将为油菜抗渍栽培调控研究提供重要的理论依据，同时为油菜耐渍评估体系的建立及优良耐渍品种的筛选提供重要的指导意义。

苗期渍害后，耐渍型油菜在根系干物质分配减少的同时，叶片干物质分配减少，缓解了生理性缺水，利于恢复期生长，而敏感型油菜根系干物质分配在渍害后增加，和叶片干物质变化不同步。耐渍型油菜在施氮90-270 kg hm-2下，薹期和花期叶片数增加，适量增施氮肥通过增加叶片数，提高光合能力，促进地上部干物质累积，为籽粒蛋白质合成奠定基础，而敏感型油菜叶片数在恢复期仍低于对照，叶面积及SPAD值下降，光合能力弱；薹期叶片可溶性蛋白在耐渍型油菜中最高，敏感型油菜中最低。敏感型品种氮代谢弱，植株长势差，进一步阻碍了籽粒蛋白质的合成。渍害油菜叶片可溶性糖含量虽降低，籽粒油脂代谢碳源减少，但由于籽粒蛋白质合成减弱，碳底物优先分配合成脂肪酸，促进了渍害下油分的累积。苗期渍害显著降低了两品种籽粒产量；但在90-180 kg ha-1施氮量下，ZS 9在渍害后产油量高于对照，GH 01在各施氮量下发生渍害后，产油量仍显著低于对照。在0-90 kg ha-1施氮下，两品种渍害叶片薹期Pn仍显著低于对照，在180-270 kg ha-1条件下虽低于对照，但差异不显著；施氮下，渍水后叶片Rubisco活性在苗期和薹期显著低于对照，在花期则高于对照，且Rubisco活性均与籽粒产量显著正相关著。ZS 9在180-270 kg ha-1下发生渍害后，薹期和花期叶片SuSy和SPS活性和对照间无显著差异；GH 01在各施氮量下发生渍害后，薹期叶片SuSy和SPS活性显著高于对照，其他时期均显著低于对照，单株产量与花期SPS活性显著正相关，表明与对照相比，耐渍型品种在适宜施氮量下，花期光合产物运转能力显著增强，而敏感型品种仍受到明显抑制，花期光合产物运能力的差异是导致两品种在发生渍害后产量存在差异的主要原因。薹期根系代谢组分析，筛选了不同处理组间存在共有差异显著代谢物pmb0874，且施氮后该代谢物均表现为上调，揭示了脂质-甘油磷脂类物质在氮肥调控渍害油菜生长中的重要作用。