半高秆超级杂交稻叶鞘对抗倒伏的影响机理及调控研究

Semi-high-stem super hybrid rice was proposed by Professor Yuan longping based the practical experience on morphological improvement of super hybrid rice and super high yield project. In essence, the purpose of super high yield is got though increasing plant height moderately. Hence, lodging resistance becomes the related key factor. In former research about the lodging resistance, more focused on stalk, but the sheath was ignored. However, the breaking-resistant strength of sheath was twice than without it, and this showed the importance of sheath. The object of improved biomass has been proved that it cannot come true by the breeding or cultivation methods on reducing plant height to strengthen the stalk. The new method has to be applied with the utilization of lodging resistance of sheath. In this project, semi-high-stem super hybrid rice in the field is as material to research the relationship between lodging resistance and key morphology and physiological index of sheath in the varieties with endurance resistance and control. The purpose is to demonstrate the variation pattern of morphology and physiological index of sheath in semi-high-stem super hybrid rice under different nitrogen level, nitrogen application, water management, and chemical regulation, to set up the model among morphology and physiology of sheath, agriculture management, and response to lodging resistance, to break through the limit of rice height and achieve the theoretical and technical support for high yield with lodging resistance.

半高秆超级杂交稻是由袁隆平院士根据超级稻植株形态改良规律及超高产实践总结提出的，本质是通过适度增加株高来提高生物量以实现超高产目标，而抗倒伏随之成为能否实现超高产目标的关键因素之一。以往抗倒伏研究及调控多以茎秆为对象，忽略了叶鞘的作用，且前期研究发现含鞘茎秆抗折力是去鞘的1～2倍，叶鞘作用巨大。前人通过降低株高强化茎秆抗倒能力的育种、栽培方法难以实现通过增加株高来提高生物量的目标，需要开展全新的抗倒高产研究，充分发挥叶鞘的抗倒伏作用。本研究以大田种植的半高秆超级杂交稻为材料，研究高产条件下半高秆超级杂交稻叶鞘耐衰品种及其对照品种的叶鞘关键形态、生理指标与抗倒伏的相关性，探明不同施氮水平、氮肥运筹、水分管理、物化调控等条件下半高秆超级杂交稻叶鞘形态生理的变化规律，建立水稻叶鞘形态生理- 农艺措施- 水稻抗倒伏响应模型，为半高秆超级杂交稻突破传统秆高的限制，实现抗倒高产提供理论依据和技术支撑。

要提高水稻产量上限应进一步提高生物量，而增加株高是提高生物量的一项有效且可行的方法。为了突破传统秆高的限制，因此必须开展全新的超高产抗倒伏研究。本研究思路通过发挥叶鞘的功能，为通过增加株高进一步提高生物量且保持抗倒伏的育种策略提供一种新思路。. 本研究在大田种植条件下，研究比较叶鞘耐衰品种及其对照品种的叶鞘抗倒能力及抗倒关键形态、生理指标差异；叶鞘抗倒关键形态、生理指标对主要农艺措施的响应及探索形成主体农艺措施—水稻叶鞘形态生理功能—超高产抗倒伏的响应模型共4个方面的研究内容。. 研究表明叶鞘耐衰品种节间包鞘、去鞘的抗折力均极显著大于对照品种。节间包鞘抗折力是去鞘抗折力的1.4~1.9倍，去鞘后的抗折力较包鞘降幅24.3%~46.8%，叶鞘能够极显著提高水稻节间的抗折力。且叶鞘在齐穗期对抗倒性弱的品种影响大，而在成熟期对抗倒性强的品种影响大。. 叶鞘耐衰品种叶鞘包茎层数、叶鞘厚度、叶鞘存活数量、叶绿素含量、纤维素、可溶性糖、硅、钾含量含量等形态及生理指标均显著或极显著大于对照品种，且下降幅度表现为叶鞘衰老品种大于叶鞘耐衰品种。且叶鞘形态生理指标与节间包鞘的抗折力呈显著或极显著正相关。表明叶鞘包茎层数、包茎厚度、叶鞘存活数量、叶绿素含量、纤维素、可溶性糖、硅、钾含量为影响叶鞘抗折力的关键形态、生理指标。. 不同农艺措施会不同程度的通过影响叶鞘形态生理功能进而影响水稻的抗倒伏特性，并对产量产生不同的影响。为了达到抗倒伏且获得较高产量的效果，因此农艺措施处理在生产上存在一个相对适宜值。. 水稻主体农艺措施—水稻叶鞘形态生理功能—超高产抗倒伏的3者之间的响应模型关键核心技术为“活鞘延衰抗倒栽培”。形成的响应模型的核心技术能够降低水稻超高产栽培中的倒伏风险，充分发挥水稻良种超高产潜力，实现农民节本增收的效果。. 本研究对于突破水稻传统秆高的限制、保持强抗倒力前提下大幅提高生物产量的超高产育种及超高产抗倒栽培调控均具有重要的意义。