控水、增密对高产氮高效水稻氮素亏缺的调节效应及机理研究

The main characteristics of rice production in China are high nitrogen(N) fertilizer inputs and low fertilizer N use efficiencies. However, a little attention has already been paid to the combined increase of rice yield and N use efficiency. Therefore, we want to study how to decrease the N application meanwhile achieving high rice yield, based on our previous research in which the rice cultivars with high yields and high N use efficiencies were screened out and their optimum N application amounts have been determined. (1) In different nitrogen deficit conditions, the effects of water and density management on rice yield and N use efficiency will be studied, and the best cultivation mode of “nitrogen-water-density” will be suggested. (2) Based on the best cultivation mode of “nitrogen-water-density”, these morphological and physiological characteristics including root, leaf, nitrogen accumulation and utilization, dry matter production and transporting will be studied, on the basis of above morphological and physiological characteristics, the regulation mechanism of water and density management on nitrogen deficiency in rice will be clarified. The understanding of “nitrogen-water-density” interaction relationship will be deepened. Furthermore, we hope to provide very useful information for high-yield cultivation on the premise of reducing nitrogen application compared with the nitrogen application that results in the highest yield.

紧扣我国水稻生产中氮肥用量大、氮肥利用率低的重大实际问题，在已有研究的基础上，选用高产氮高效水稻基因型为对象，以其最适施氮量（最高产施氮量）为标准，通过减氮形成氮素亏缺，开展控水、增密对高产氮高效水稻氮素亏缺的调节效应及机理研究：（1）以正常高产栽培为对照，在不同程度氮素亏缺条件下研究控水、增密对高产氮高效水稻产量形成和氮素吸收利用的影响，明确“减氮-控水-增密”最佳耦合模式，揭示控水、增密对高产氮高效水稻氮素亏缺的调节效应。（2）基于“减氮-控水-增密”最佳耦合模式，以“不减氮-不控水-不增密”模式（CK1）和“减氮-不控水-不增密”模式（CK2）为对照，研究“减氮-控水-增密”最佳耦合模式下高产氮高效水稻的根系形态生理及氮素吸收利用特性、叶片形态生理及光合物质生产转运特性，进而阐明控水、增密对高产氮高效水稻氮素亏缺的调控机理，为大面积水稻生产合理减氮和高产高效栽培提供重要理论支撑。

以水稻减氮条件下如何实现高产为研究目标，探索栽培措施对水稻减氮后氮素亏缺的调控效应及生理机制。项目选用高产氮高效型杂交籼稻品种为试材，以常规高产栽培为对照，在两种减氮条件下（减氮10%和减氮30%）分别设置9种控水增密耦合模式，研究控水增密模式对水稻氮素亏缺的调节效应及生理机理，主要取得以下两方面研究结果：（1）减氮10%条件下，2种控水增密模式较对照增产，7种模式较对照减产，最佳耦合模式为“轻干湿交替灌溉-增密20%”，该模式较对照增产3.7%，可实现减氮高产；减氮30%条件下9种控水增密模式均较对照减产，最佳耦合模式为“中干湿交替灌溉-增密40%”，较对照减产16.2%。（2）单一减氮栽培造成水稻光合生产和氮素积累量显著降低，造成显著减产；减氮增密栽培能增加水稻光合生产量和氮素积累量，可一定程度上弥补减氮造成的产量损失，但碳氮同化物向穗部转运率低，收获指数较低；减氮控水增密栽培能在较高群体生长量基础上，通过延缓植株衰老保持抽穗后叶片和根系较高的光合能力和氮素积累量，促进干物质和氮素向籽粒转运，显著提高收获指数和氮肥利用率，实现节水减氮增产。本研究在《作物学报》、《The Crop Journal》等重要期刊发表论文7篇，出版学术专著1部，研究结果可为水稻减氮高产栽培提供重要理论依据。