秋干季节与湿润夏季对美洲黑杨“中嘉2”光合作用的影响

Effect of Dry Days in Automn and Wet Days in Summer on Photosynthesis of Populus deltoides CL.'Zhongjia 2'

[目的]对美洲黑杨杂交品种"中嘉2"光合作用秋干季节与湿润季节变化规律进行系统性比较研究,探索其光合作用的规律及其光合效率午间降低的机制,为杨树抗旱育种提供理论依据。[方法]在自然条件下对中南地区的优良杨树品种-中嘉2在湿润夏季和秋干季节的光合特征进行了观测分析。[结果]在秋季的干旱胁迫状态,气孔及非气孔限制的共同作用导致秋干季节的净光合速率(Pn)显著低于湿润夏季。秋干季节的光合"午休"现象与气孔无关,此时光合作用受非气孔因素限制,即低湿、强光条件下杨树叶片发生了明显的光抑制或光呼吸。单个生态生理因子对净光合速率影响曲线呈显著水平极高的二项式关系,湿润季节与秋干季节典型晴天净光合速率的最优多元回归模型为:Y=-3.2479-0.0016X1+213.5016X3+0.2829X5-0.0097X7(X1-PAR,X3-CE,X5-Tleaf,X7-Ca)。[结论]羧化效率(CE)、叶面温度(Tleaf)是影响Pn的主导生理生态因子。

[ Objective] By comparing photosynthetic characteristics of Populus deltoides CL. ＇Zhongjia 2＇ between dry days in autumn and wet days in summer, expect to reseach photeayntbetic rules and the mechanism that photosynthetic effect reduces in noon, in order to provide theory foundation for poplar anti-drought breeding.[ Method] In this paper the photosynthetic characteristics of Populus deltoides CL. ＇Zhongjia 2＇ leaves during dry days in autumn and wet days in sumer were studied. [ Result ] the results of field study indicate that, compared with wet June, the ecopbysiological factors displayed different patterns in dry September. Stomatal inhibition and non-stomatal inhibition acted together, and resulted in the decreasing of net photosynthetic rate （Pn） under drought stress in September. The results showed that lighy inhibition or light respiration may be the main factors resulting in the noon break of Pn under low relative humidity and stronger light. The results also showed that the relation curve between Pn and single ecophysiological factor fit polynomial. The most excellent equation of the diurnal variation of Pn is attained by the method of stepwise multiple regression as follows： Y = -3.247 9-0.001 6 X1 ＋213.501 6 X3 ＋0.2829 X5 -0.0097 X7（X1-PAR,X3-CE,X5-Tleaf, X7-Ca）.[Conclusion] Carboxylation efficiency （CE） and leaf temperature（Tleaf） is the main ecophysiological factors that effect Pn.