水氮互作调控超级稻弱势籽粒充实的生理机制

The super rice is almost large-spike type cultivar, the poor filling of inferior spikelets of large-spike type cultivar is a general problem, and limits the realization of great yield potential. The main factors in rice cultivation are water and nitrogen, interaction of water and nitrogen fertilizer is main measures contributed to a high grain yield of rice, but few studies on physiology mechanism of water and nitrogen fertilizer interaction regulating the filling of inferior of super rice have been reported. The study will take the endogenous hormone contents-RNA and mRNA-endosperm development and activities of key enzymes involved in sucrose-to-starch conversion-grain filling-yield and quality formation as the main line. The main contents of the study including: (1) Effect of water and nitrogen fertilizer interaction on super rice cultivars with significant difference in seed setting characteristics and grain filling in superior and inferior spikelets of same cultivar. (2) Under water and nitrogen fertilizer interaction, the changes of endogenous hormones during the endosperm development and the proportional relationship among endogenous hormones. (3) Under water and nitrogen fertilizer interaction, the changes laws of endosperm development and activities of key enzymes involved in sucrose-to-starch conversion. (4) Under water and nitrogen fertilizer interaction, the technique regulation approaches of regulating hormones synthesis and balance and improving grain filling of inferior spikelets of super rice. To reveal the physiology mechanism of water and nitrogen fertilizer interaction regulating the filling of inferior of super rice, propose the regulation approach of water and nitrogen fertilizer interaction enhancing grain filling of inferior spikelets, and establish the corresponding water and nitrogen fertilizer management measures to give full play to yield potential of super rice.

超级稻几乎均为大穗型品种，但大穗型品种弱势粒充实不良是普遍问题，严重影响超级稻优势发挥。水分和氮素是水稻栽培的主要因子，水氮互作是实施水稻高产的主要措施，但是水氮互作调控超级稻弱势粒充实生理机制的研究几乎是空白。本项目以内源激素含量-RNA和mRNA--胚乳发育、蔗糖淀粉代谢途径关键酶活性--籽粒充实--产量和品质形成的研究为主线。研究内容：（1）水氮互作对结实特性明显差异的超级稻及同一品种强、弱势籽粒结实指标的影响。（2）水氮互作条件下，胚乳发育充实过程中内源激素水平的变化及各激素间的比例关系。（3）水氮互作条件下，蔗糖-胚乳发育、淀粉代谢途径关键酶活性的变化规律。（4）水氮互作条件下，调控激素产生和激素间平衡、改善超级稻弱势粒籽粒充实的技术调控途径。通过研究，揭示水氮互作调控超级稻弱势籽粒充实的生理机制，提出水氮互作提高弱势籽粒充实的调控途径，制定相应的肥水管理措施。

超级稻几乎均为大穗型品种，但大穗型品种弱势粒充实不良是普遍问题，严重影响超级稻优势发挥。水分和氮素是水稻栽培的主要因子，水氮互作是实施水稻高产的主要措施，但是水氮互作调控超级稻弱势粒充实生理机制的研究几乎是空白。本项目以内源激素含量--蔗糖淀粉代谢途径关键酶活性--籽粒充实主线开展研究。.研究内容：（1）水氮互作对超级稻弱势籽粒充实的影响。（2）水氮互作对胚乳发育充实过程中内源激素水平、淀粉代谢途径关键酶活性的影响。（3）改善超级稻弱势粒籽粒充实的技术调控途径。. 重要结果：（1）施氮量和灌溉方式对水稻产量和籽粒灌浆的影响有明显的互作效应。中等施氮量与轻干湿交替灌溉相结合（MN+WMD），可以促进弱势粒灌浆，提高弱势粒粒重，进而提高产量和氮肥利用效率。（2）在中等施氮量与轻干湿交替灌溉相结合（MN+WMD）栽培模式下，根系和籽粒中内源激素含量的增加、淀粉合成相关酶活性及基因表达量的增强、叶片抗氧化酶的活性与光合速率的提高、以及花后茎中NSC向籽粒转运的促进是提高弱势粒灌浆和粒重、增加产量和氮肥利用效率的重要生理原因。. 科学意义：（1）明确了中等施氮量与轻干湿交替灌溉相结合可以促进弱势粒充实与提高氮肥利用效率，这一结果对水稻高产高效生产有重要的应用价值。（2）从内源激素、酶活性和基因表达、叶片抗氧化酶的活性、叶片光合和物质转运等方面揭示了水氮互作影响水稻弱势粒灌浆的机理，对于探明作物弱势粒充实差的原因和促进弱势粒灌浆的生理调控途径，提供了科学论据。