摘要
夏秋两季在保证土壤充足水分的条件下,杨树"中潜6"(Populus deltoides CL.‘Zhongqian 6’)一年生插条苗受空气干旱胁迫后净光合速率(Pn)受显著抑制。试验结果显示,尽管干燥夏秋二季杨树所处的生态环境不同,但在夏季如果受空气干旱胁迫,同样会引起与干燥秋季相同的生理因子变化,即气孔导度、Rubisco效率均降低,从而使净光合速率减弱。利用逐步多元回归分析建立最优多元回归模型如下:干燥夏季为Y=-1.6807+0.0036 X1-0.1243 X2+60.7432 X4,;干燥秋季为Y=-28.1958+0.0078 X1+0.3177 X3-0.0593 X5+0.0989 X6(X1-PAR,X2-RH,X3-Tleaf,X4-Gs,X5-Ci,X6-Ca,Y-Pn)。
The present paper reported that the net photosynthetic rate （Pn） of annual seedlings of Populus dehoides CL. Zhongqian 6＇ was restrained remarkably under air drought stress even if the soil water was enough in Summer and Automn. In despite of the entironment of poplar in Summer and Automn was different, physiological factors changed with the same tendency under air drought stress. Stomata/conductance（Gs） and Ribulose- 1,5 -bisphosphate carboxylase （Rubisco） efficiency were decreased, and resulted in the decreasing of Pn. The most excellent equations of the diurnal variation of Pn were attained by the method of stepwise multiple regression as follows ： Y = -1. 6807 ＋ 0.0036 X1 -0. 1243 X2 ＋ 60.7432 X4 （in dry Summer ） ; Y = -28. 1958 ＋ 0. 0078 X1 ＋ 0. 3177 X3 - 0. 0593 X5 ＋ 0. 0989 X6 （ in dry Automn）. （ X1 - PAR, X2 - RH, X3 - Tleaf,X4 - G8,X5 - Ci, X6 - Ca, Y - Pn）.
