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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.
The photosynthetic gas exchange parameters and photosynthetic rate (Pn) response curve of wheat at jointing stage were studied to study the effects of nitrogen on photosynthesis of wheat leaves under long-term high atmospheric CO2 concentration (760μmol.mol-1). The results showed that (Pn), transpiration rate (Tr) and instantaneous water use efficiency (WUEi) of wheat leaves increased with nitrogen application at long-term high CO2 concentration. Compared with normal atmospheric CO2 concentration, Pn WUEi increased, stomatal conductance (Gs) and intercellular CO2 concentration (Ci) decreased.With the increase of photosynthetically active radiation, Pn and WUEi in wheat leaves under high atmospheric CO2 concentration were higher than those under normal atmospheric CO2 treatment, while Gs was lower , While there was no significant change in Ci and Tr.Gs and Pn, Tr and WUEi of wheat leaves showed a linear positive correlation under high nitrogen levels, but negative correlation between Gs and Ci under normal atmospheric CO2 concentration, The correlation between Gs and Pn, WUEi of wheat leaves under low nitrogen level was linear, but positively correlated with Ci and Tr, which indicated that Pn of wheat leaves with low nitrogen level under high atmospheric CO2 concentration was restricted by non-stomatal factors.