旱地覆膜高产玉米对大气CO2浓度升高的响应与调控机理

It is abundently clear that human activities have caused atmospheric CO2 concentration to increase at an accelerating pace, and rising atmospheric CO2 levels alter the physiology of many plant species. But little is known the effects of elevated CO2 on growth, physiology and yield of high-yield maize (Zea mays L.) grown with film mulching under dryland conditions. To investigate the effects of elevated CO2 on growth and yield of high-yielding film-mulched maize (Xianyu 335 cultivar) under dryland conditions, and to evaluate the interactions between management practices (including soil water condition, N supply) and elevated CO2, a series of independent but complementary field experiments will be conducted in south Loess Plateau. In these field experiments, maize will be planted in sunlit open top chambers (OTCs) at ambient (390 μmolomol-1) or elevated (700 μmolomol-1) atmospheric CO2 concentration with different water and N supply. As a result, this project will identify the effects of elevated CO2 on high-yield maize from stomatal morphology, stomatal density, leaf area, canopy photosynthesis, evapotranspiration rate, C and N accumulation and retranslocation. Also this project will quantify the impacts of potential climate change on dryland maize biomass and yield, as well as provide the suggested adaptive management for dryland maize under elevated CO2 conditions.

针对旱地覆膜高产玉米对大气CO2浓度升高如何响应，以及对水、氮需求量如何变化的研究，是科学判断旱地高产玉米未来生产前景，应对气候变化挑战的基础。本项目拟以旱地覆膜高产春玉米单作体系为对象，在田间利用开顶式气室模拟CO2浓度升高的环境，利用气孔形态、气体交换和叶面积测定技术，以及碳氮化学计量技术，研究CO2浓度升高-气孔形态、密度-叶面积-光合-蒸腾-生育期-个体生物量建成-碳氮累积与转运-生产力之间的联动关系，探明旱地覆膜高产玉米源库器官碳氮耦合特征、光合产物转运过程及生产力对CO2浓度升高的响应特征与机制，明确水分、氮素与玉米对CO2浓度升高响应的耦合关系，从气孔、叶片、个体、群体尺度以及土壤养分库动态角度揭示CO2浓度升高条件下产量形成的水氮调控机理，提出当前高产模式应对CO2浓度升高的适应性调整措施。以期为通过水、氮调控技术应对气候变化挑战提供理论依据与实践指导。

针对旱地覆膜高产栽培玉米对大气CO2浓度升高如何响应，以及对水、氮需求量如何变化的研究，是科学判断旱地高产栽培玉米生产前景，应对气候变化挑战的基础。本项目通过多年田间研究，明确了旱地覆膜高产栽培玉米从气孔-叶片-个体水平上对大气CO2浓度升高的响应特征，探明了水分、氮素与高产栽培玉米对大气CO2浓度升高响应的耦合关系，指出未来气候变化条件下覆膜仍是旱作农业的有效水分管理措施，揭示了仅在大气CO2浓度升高单一条件下，旱作春玉米增产不显著，而在大气CO2浓度升高与开顶式气室（OTC）小幅增温（本试验改进的OTC增温为日均0.4 ℃）联合作用下，旱作覆膜玉米产量显著增加，本研究还对未来气候变化条件下的土壤质量进行了探讨。以上研究结果为明确未来气候条件下旱作玉米产量及其土壤质量，应对未来气候变化提供了数据基础，对未来气候变化条件下旱作玉米种植、管理也具一定指导意义。