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作 者 ：付士磊^1,2;周永斌³;何兴元¹;陈玮¹

期 刊 ：应用生态学报 2006年 17卷 11期 页码：2016-2019

关键词：杨树；

摘 要 ：采用PEG模拟干旱胁迫的方法，利用气体交换法和叶绿素荧光技术，研究了干旱胁迫下小青杨（Populus pseudo-simonii）的光合生理变化.结果表明,干旱胁迫初期，小青杨的净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(g_s)和胞间CO₂浓度(C_i)值均随干旱胁迫增强而下降，杨树P_n的下降主要是由于g_s下降引起的；干旱胁迫后期,C_i值逐渐升高，非气孔限制成为光合作用的主要限制因子.干旱胁迫后期,PSⅡ原初光能转化效率(F_v/F_m)和PSⅡ潜在活性(F_v/F_o)明显下降，光抑制增强，光合电子传递受阻.POD酶的活性在胁迫初期升高，后期降低，说明干旱胁迫初期对保护系统酶活性升高有诱导作用，随着胁迫时间的延长，F_v/F_m和F_v/F_o降低，活性氧清除酶活性下降，活性氧代谢的平衡被打破，导致光合器官的伤害.由此表明,干旱胁迫后期P_n的降低与PSⅡ荧光参数及POD酶活性下降有关.

Abstract:In this paper, the effects of drought stress simulated by PEG on the photosynthesis
of Populus pseudo-simonii were monitored by gas exchange and chlorophyll fluorescence techniques. The results showed that in the early phase of drought
stress, net photosynthetic rate (P_n), transpiration rate (T_r), stomata conductance (g_s),
and intercellular CO₂ concentration (C_i) decreased with increasing stress, and
the decrease of P_n was mainly related to the decreased g_s. In the late phase,
C_i increased gradually, while F_v/F_m and F_v/F_o decreased significantly. POD activity
increased in the early phase, but decreased in the late phase. All of these indicated
that in the early phase of drought stress, stomata closure was the main factor
limiting P. pseudo-simonii photosynthesis, while in the late phase, the main limiting factor was non-stomatal.A short period of drought stress to the stress resulted in the decrease of PS Ⅱ efficiency and POD activity.

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