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作者	单位
于佳¹，于显枫²，郭天文²，张绪成^2,3，马一凡²	（1. 甘肃农业大学农学院，甘肃兰州 730070； 2. 甘肃省农业科学院农业部西北作物抗旱栽培与耕作重点开放实验室，甘肃兰州 730070； 3. 中国农业大学资源环境学院，北京 100094）

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中文摘要:

为明确高大气CO₂浓度下小麦叶片光合作用的适应机制及氮素的调控作用，利用开顶式气室，通过盆栽试验，测定和分析了不同大气CO₂浓度和施氮量下小麦拔节期叶片的光合参数、叶绿素含量等指标。结果表明，高大气CO₂浓度（760 μmol·mol^-1）处理的小麦叶片的叶绿素含量、光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均随着施氮水平的升高而升高，平均增幅分别为31.6%、69.6%和57.6%，而胞间CO₂浓度(Ci)和水分利用效率(WUE)随施氮水平的升高而呈先下降后上升的趋势。高大气CO₂浓度下小麦叶片Pn、Ci和WUE显著高于正常CO₂浓度（400 μmol·mol^-1）处理，平均增幅分别为36.8%、74.0%和102.7%。在400 μmol·mol^-1 CO₂浓度下测定时，与正常大气CO₂浓度下生长的小麦相比，高大气CO₂浓度下生长的小麦拔节期叶片Pn在高施氮水平（0.2 g N·kg^-1土）下未发生下调，而在低、中施氮水平（0和0.1 g N·kg^-1土）下叶片Pn明显降低。因此，高大气CO₂浓度下施氮可显著提高小麦叶片的Pn和WUE，且充分供氮可使叶片不发生光合适应现象，这可能与较高的施氮水平提高了高大气CO₂浓度下小麦叶片的叶绿素含量有关。

英文摘要:

Photosynthetic gas exchange papermeters and chlorophyll content of spring wheat (Triticum aestivum L.)leaves which grown in either elevated CO₂(760 μmol·mol^-1) or ambient CO₂ (400 μmol·mol^-1) and at 3 nitrogen nutrition levels (0, 100, 200 mg·kg^-1 soil) were investigated in the pot experiment, to understand the effects of elevated atmospheric CO₂ concentration and nitrogen application rates on photosynthesis of wheat leaves. The results showed that, the leaf chlorophyll content, net photosynthesis(Pn), stomatal conductance(Gs), transpiration(Tr) of spring wheat leaves in elevated atmospheric CO₂ concentration increased with the increase of nitrogen application rate, compared to the no nitrogen application treatment, which increased by 31.6%, 69.6% and 57.6% in average, respectively. However, the intercellular CO₂ concentration (Ci) and leaf water use efficiency (WUE) decreased and then increased with the increase of nitrogen application rate. The Pn, Ci and WUE of spring wheat leaves which exposure to elevated atmospheric CO₂ concentration were higher than the ambiment atmospheric CO₂ concentration significantly, by 36.8%, 74.0% and 102.7% in three nitrogen application rates, respectively. At jointing stage, the decrease of photosynthetic acclimation did not happened in the wheat leaves of high N treatment which exposure to elevated atmospheric concentration, but the photosynthetic rate in the wheat leaves of middle and lower N treatments, which grown under elevated atmospheric concentration were lower than that at the ambiment treatments significantly. Consequently, the Pn and WUE of spring wheat would increase when the nitrogen applicated under elevated atmospheric CO₂ concentration conditions, and the photosynthetic acclimation did not increase, this may be related with the increased leaf chlorophyll content while nitrogen were applied.

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