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Photoinhibition of photosynthesis in sweet Viburnum leaves under natural conditions

Guo Lianwang, Xu Daquan

Shanghai Institute of Plant Physiology, Academia Sinica. Shanghai

Abstract

The pnoto thesis studied by chloroplasts and thylakiods was, in most cases. observed under extreme condifions. Although a few authors reported photoinhibition observed under natural conditions with no environmental stress besides high light, the cause of this type of photoinhibition is still unknown. To clarify it, we studied photoinhibition of Viburnum odoratissmum leaves under natural conditions. After exposure to midday strong light, the apparent quantum yield(AQY) and PSⅡphotochemical efficiency (F_(v)/F_(m)measured in the afternoon declined compared to that measured in the morning indicating that photoinhibition frenquently occurs in Viburnum odoratissimum leaves under natural conditions with midday high light as the only stress. recovered almost to the level observed in the morning, 1 hour after shading following the decrease after exposure to midday high light. After 3h of midday strong light, the light-saturated photosynthetic rate (P_(max))showed only an insighificant fall, but the initial fluorescence (F_(o))decreased The content of Q_(B) protein in leaves did not show evident change after illumination imitating midday strong...

Key words: Photoinhibition;Apparent quantum yield;PS Ⅱ photochemical efficiency;Fluorescence quenching;Q_(B) protein;Viburnum odoratissimum

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Citing This Article：

Guo Lianwang, Xu Daquan. Photoinhibition of photosynthesis in sweet Viburnum leaves under natural conditions. Acta Physiol Sin 1994; 46 (1): (in Chinese with English abstract).