春玉米密植高产群体(15吨/公顷以上)弱势粒库特征及其调控机理研究

Our studies showed that fifty-nine stations, in the irrigated plain regions in Inner Mongolia, demonstrated six year continuous unit maize yields of 15-20 tons/ha (27 spring maize hybrids), and that demonstration fields (667 ha in area) produced 15 tons/ha. We have achieved initial success in revealing the physiological mechanism of high yield (above 15t/ha) cultivation in crowded populations. However, the abortion and the filling conditionality of inferior kernels of high yield spring maize under crowded conditions induced decrease in individual kernel number and limited the population sink capability. In order to promote the kernel setting and the grain filling of inferior kernels, so as to increase the individual kernel number and then remove the sink limit and finally explore the yield potential of spring maize, the sink traits of inferior kernels and the physiological and biochemical process in the setting and filling processes of inferior kernels of high yield spring maize will be systematicly researched in this study. Moreover, the key limiting factors for the setting and grain filling of inferior kernels, and the regulatory pathways for them will be illuminated in this research. The results is expected to provide spring maize production with theoretical basis and technical templates in tapping maize productivity potential and enhancing resource use efficiency.

本项目在内蒙古平原灌区连续7年29个品种62个点次实现亩产1～1.34吨、万亩高产示范方实测平均亩产达1吨，且高产（15吨/公顷以上）栽培生理机制研究取得阶段性成果的基础上，针对春玉米密植高产群体弱势粒败育和灌浆受限，导致个体穗粒数提高难度大、群体库容受限进而限制产量挖潜的关键科学问题，以促进弱势粒建成与灌浆实现穗粒数提高，去除库容限制实现产量挖潜为目标，对春玉米密植高产群体弱势粒库特征及其建成、灌浆过程的生理生化变化进行系统研究，明确弱势粒建成与灌浆的关键限制因子与调控途径，为高产春玉米产量挖潜及资源增效栽培提供理论依据与技术途径。

本项目针对春玉米密植高产群体弱势粒败育和灌浆受限，导致个体穗粒数提高难度大、群体库容受限进而限制产量挖潜的关键科学问题，以促进弱势粒建成与灌浆实现穗粒数提高，去除库容限制实现产量挖潜为目标，在控制授粉、肥密互作和外源化控条件下，对春玉米密植高产群体弱势粒库特征、弱势粒建成与灌浆过程的生理生化变化及栽培调控途径进行系统研究，为明确弱势粒建成与灌浆的关键限制因子与调控途径提供理论依据。主要研究结果如下：.（1）密植群体玉米果穗弱势籽粒的败育或灌浆受限不受其库容量的限制，籽粒形成期的库活性是弱势粒败育或灌浆受限的核心限制因子。.（2）弱势粒库活性受其多胺和乙烯平衡的调控，糖分供应充足时，多胺大量合成抑制乙烯释放，促进SAI活性使糖分向籽粒中卸载，使弱势粒成功建成；糖分供应不足时，多胺合成受限而乙烯大量合成，抑制SAI活性，还原糖卸载受阻，籽粒败育或灌浆受限。.（3）氮密互作通过调控籽粒库活性而影响弱势粒败育率和个体库容，且主要受密度影响，这与植株窗口期的氮素积累速率和光合同化能力有关；外源化控同样通过调节SAI活性影响弱势粒建成，可显著降低败育率、提高个体库容和子粒产量。.研究结果明确了弱势粒建成与灌浆受限的核心限制因子和栽培调控途径，达到了预期研究目标。通过项目研究，发表研究论文6篇，其中SCI收录2篇；获得中华农业科技三等奖1项；培养硕士研究生2人，完成了各项任务指标要求。