【摘要】 干旱条件下冬小麦叶片光化学效率（Ｆｖ／Ｆｍ）的降低伴随着叶黄素循环组分玉米黄质含量的增加。干旱初期，Ｆｖ／Ｆｍ 的降低约在暗置过夜后完全恢复。当干旱诱导的玉米黄质含量的增加达最大值时，Ｆｖ／Ｆｍ 不可逆下降，Ｆｏ 上升，表明发生了光破坏。与老叶相比，干旱条件下功能叶具有较高的玉米黄质含量，对光破坏的抗性较强。推测干旱条件下老叶不可逆衰老与其依赖于叶黄素循环的耗散过剩光能能力的下降有关。更多还原

【Abstract】 The age related effect of drought stress on fluorescence parameters and photosynthetic pigments in winter wheat leaves was studied. In all leaves examined, drought induced declines in PSⅡ photochemical efficiency measured as midday values of Fv/Fm were almost completely reversible overnight, such that the predawn Fv/Fm remained largely unchanged during the initial 6～8 days of stress. The violaxanthin (V) deepoxidation into zeaxanthin (Z) increased in response to drought. When the increase of Z reached a plateau level, photoinhibitory damage, as indicated by a net increase in Fo and sustained decline in Fv/Fm, became evident. Compared with older leaves, younger leaves showed a higher capacity for Z synthesis and also showed a lower sensitivity to photodamage caused by a combination of drought and high sunlight stresses. This observation suggests an important role of Z in the protection of photosynthetic apparatus against photoinhibitory damage. We speculate that during drought stress, older leaves senesced irreversibly because they may not be able to increase the Z synthesis to cope with the excessive light stress.更多还原