中文摘要：

为给未来大气CO2浓度升高条件下超高产小麦的氮肥管理提供技术支撑，在大田条件下利用LI-6400便携式光合作用测定仪，采用开放式气路测定了不同CO2浓度下小麦旗叶的净光合速率（Pn）、气孔导度（Gs）、胞间CO2浓度（Ci）、蒸腾速率（Tr）、水分利用效率（WUE）等相关指标，分析了施氮量对开花期超高产小麦旗叶CO2响应曲线的影响。结果表明，氮素对开花期超高产小麦旗叶的CO2响应有较大的调节作用，随着外界CO2浓度的升高，小麦旗叶的光合参数Pn、WUE逐渐上升并在800umol CO2·mol^-1左右趋于稳定。但施氮量在375kg／ha条件下Pn、WUE反而较施氮量为300kg／ha的降低，说明在合理的施氮范围内，施氮和提高外界CO2浓度能通过增强小麦旗叶对胞间CO2的利用能力来提高光合速率、降低蒸腾速率、提高水分利用效率，从而改善旗叶的光合性能。

英文摘要：

The effects of nitrogen supply on the CO2-response curve in flag leaves of superhigh-yield winter wheat at flowering stage were studied under field conditions to provide scientific and technological support for nitrogen management of the superhigh-yield winter wheat. The net photosynthesis rate（Pn）, intercellular CO2 concentration（Ci）, stomatal conductance（Gs）and transpiration rate （Tr）in superhigh-yield winter wheat were measured using LI-6400 Portable Photosynthesis System with an open flow gas exchange system. The results showed that nitrogen could regulate the CO2-response of the flag leave in some degree at flowering stage. The net photosynthesis rate（Pn）, water use efficiency（WUE）increased as the atmospheric CO2 concentrations elevated and kept stable at 800 umol CO2 · mol^-1. But under N 375 kg/ha application the net photosynthesis rate（Pn）and water use efficiency（WUE） decreased compared to N 300 kg/ha. On the rational nitrogen application amount, nitrogen application and elevating the atmospheric CO2 concentrations can increase the net photosynthesis rate （Pn）, decrease the transpiration rate, improve the WUE to improve the photosynthetic performance of the flag leave by enhancing the ability to use the intercellular CO2. The highest grain yield was observed in the treatment with N 300 kg/ha application.