控释氮肥调控高产玉米花后氮分配与光合氮利用效率的生理机制

高产玉米要求花后更多氮素的持续供应才能维持其正常的光合作用，累积更多干物质，降低早衰风险。但是目前集约化生产以及成本约束限制了多次施肥的进行，控施氮肥的一次性施入由于其省工、高效受到广泛关注。目前对于玉米花后氮素供应研究多停留在植株和群体层面，缺乏对于控施氮肥一次施用影响玉米花后叶片氮分配以及光合氮利用效率的研究。本项目拟安排3年的田间试验，利用15N标记不同氮素（控释氮和尿素氮），采用郑单958作为材料，在田间设置不同比例控释氮肥和尿素掺混的一次性施肥试验，以期在(i)植株尺度，明确玉米花后控释氮在植株各器官的吸收、分配和转移特性；(ii)冠层尺度，探究控释氮肥影响玉米花后冠层光、氮分布以及相应的关键酶活性的生理机制；(iii)叶片尺度，探究控释氮肥对玉米花后穗位叶光合系统氮分配以及光合氮利用效率的影响。为进一步利用控释氮肥优化高产玉米花后氮素分配和提高光合氮利用效率提供理论依据。

More nitrogen should be applied after silking stage in order to maintain normal photosynthesis, accumulate more biomass, reducing the risk of premature aging in high-yield maize system. However, multiple fertilizations were restricted because of large-scale intensive production and laboring saving, one-off application with controlled release nitrogen had been paid more attention due to its high efficiency. So far, more studies focus on the nitrogen supply of high-yield maize during post-silking stage at plant and population level, and lacking of attention to study on the nitrogen partitioning and photosynthetic nitrogen use efficiency(PNUE) in ear-leaf of maize for control released nitrogen one-off application. In our study, a three-year field experiment of different proportions combined with controlled release and normal nitrogen was conducted, with different nitrogen sources(controlled release nitrogen and urea nitrogen) labeling 15N and variety ZhengDan 958(ZD958) as the selected material, the specific contents are as follows:(i) Identifying the distribution and transfer of controlled release nitrogen in different organs of maize during post-silking stage at the level of plant scale; (ii) Exploring the light and nitrogen distribution, the activities of key enzymes of maize leaves during post-silking stage at the level of canopy scale; (iii) Exploring the nitrogen partitioning and PNUE in ear-leaf of maize at the level of leaf scale. The purpose of this study is to provide the theoretical foundation for the optimization nitrogen partitioning and improvement of PNUE in ear-leaf during post-silking stage of high-yield maize by controlled release nitrogen one-off application.