氮素对高大气CO2浓度下小麦叶片光合作用的影响

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（P_n）响应曲线,研究了氮素对长期高大气CO₂浓度（760 μmol·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P_n、蒸腾速率（T_r）和瞬时水分利用效率（WUE_i）;与正常大气CO₂浓度相比,高大气CO₂浓度下小麦叶片的P_n和WUE_i增加,气孔导度（G_s）和胞间CO₂浓度(C_i）降低.随光合有效辐射的增强,高大气CO₂浓度下小麦叶片的P_n和WUE_i均高于正常大气CO₂浓度处理,G_s则较低,而C_i和T_r无显著变化.高氮水平下小麦叶片G_s与P_n、T_r、WUE_i呈线性正相关,G_s与C_i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G_s与P_n、WUE_i无相关性,而与C_i和T_r呈线性正相关,表明高大气CO₂浓度下低氮水平的小麦叶片P_n由非气孔因素限制.

Effects of nitrogen fertilization on wheat leaf photosynthesis under elevated atmospheric CO2 concentration.

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 (P_n), transpiration rate (T_r), and instantaneous water use efficiency (WUE_i). Comparing with those under ambient atmospheric CO₂ concentration, the P_n and WUE_i under the elevated atmospheric CO₂ concentration increased, while the stomatal conductance (G_s) and intercellular CO2 concentration (C_i) decreased. With the increase of light flux intensity, the P_n and WUE_i under the elevated atmospheric CO₂ concentration were higher those under ambient atmospheric CO₂ concentration, G_s was in adverse,while C_i and T_r had less change. At high fertilization rate of N, the G_s was linearly positively correlated with P_n, T_r, and WUE_i, and the G_s and C_i 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 G_s had no correlations with P_n and WUE_i but linearly positively correlated with C_i and T_r. It was suggested that under the elevated atmospheric CO₂ concentration, the wheat leaf P_n at low N fertilization rate was limited by non-stomatal factor.