中文摘要：

通过测定小麦拔节期叶片的光合气体交换参数和光强-光合速率（Pn）响应曲线,研究了氮素对长期高大气CO2浓度（760μmol.mol-1）下小麦叶片光合作用的影响.结果表明：在长期高大气CO2浓度下,增施氮肥能提高小麦叶片Pn、蒸腾速率（Tr）和瞬时水分利用效率（WUEi）;与正常大气CO2浓度相比,高大气CO2浓度下小麦叶片的Pn和WUEi增加,气孔导度（Gs）和胞间CO2浓度（Ci）降低.随光合有效辐射的增强,高大气CO2浓度下小麦叶片的Pn和WUEi均高于正常大气CO2浓度处理,Gs则较低,而Ci和Tr无显著变化.高氮水平下小麦叶片Gs与Pn、Tr、WUEi呈线性正相关,Gs与Ci在正常大气CO2浓度下呈线性负相关,但高大气CO2浓度下二者无相关性;低氮水平下小麦叶片的Gs与Pn、WUEi无相关性,而与Ci和Tr呈线性正相关,表明高大气CO2浓度下低氮水平的小麦叶片Pn由非气孔因素限制.

英文摘要：

In this paper,the effects of nitrogen（N） fertilization on the wheat leaf photosynthesis under long-term elevated atmospheric CO2 concentration（760 μmol·mol-1） was studied,based on the measurements of photosynthetic gas exchange parameters and light intensity-photosynthetic rate response curves at jointing stage.Under the long-term elevated atmospheric CO2 concentration,applying sufficient N could increase the wheat leaf photosynthetic rate（Pn）,transpiration rate（Tr）,and instantaneous water use efficiency（WUEi）.Comparing with those under ambient atmospheric CO2 concentration,the Pn and WUEi under the elevated atmospheric CO2 concentration increased,while the stomatal conductance（Gs） and intercellular CO2 concentration（Ci） decreased.With the increase of light flux intensity,the Pn and WUEi under the elevated atmospheric CO2 concentration were higher those under ambient atmospheric CO2 concentration,Gs was in adverse, while Ci and Tr had less change.At high fertilization rate of N,the Gs was linearly positively correlated with Pn,Tr,and WUEi,and the Gs and Ci had no correlation with each other under the elevated atmospheric CO2 concentration but negatively correlated under ambient atmospheric CO2 concentration.At low fertilization rate of N,the Gs had no correlations with Pn and WUEi but linearly positively correlated with Ci and Tr.It was suggested that under the elevated atmospheric CO2 concentration,the wheat leaf Pn at low N fertilization rate was limited by non-stomatal factor.