Issue Archive

The causes of widday decline of photosynthetic efficiency in cotton leaves under field coditions

Guo Lianwang, Xu Daquan, Shen Yungang

Shanghai Institute of Plant Physiology. The Chinese Academy of Sciences. Shanghai

Abstract

The relationship between changes in photosynthetic efficiency and photoinhibition as well as photorespiration in cotton leaves under field coditions was studied by measuring photosynthetic efficiency of CO_(2) fixation and O_(2) evolution, photochemical efficiency of photosystem II (F_(v)/F_(m))and photorespiratory rate with a portable ADC photosynthetic gas analysis system, a portable fluorometer (CF-1000) and a leaf disc O_(2)-electrode. After exposure to midday strong light on clear days or strong artificial light for about 3 h, photosynthetic efficiency and F_(v)/F_(m) of cotton leaves declined, while photorespiratory rate increased. Also, under ambient air conditions the extents of decreases were always bigger for photosynthetic efficiency of CO_(2) fixation than for F_(v)/F_(m). However, when photorespiration was inhibited under saturating CO_(2), photosynthetic efficiency and F_(v)/F_(m) decreased by a similar percentage, as compared with control values before exposure to strong light.

Key words: Photosynthetic efficiency;Photochemical efficiency of PS Ⅱ;Photoinhibition; Photorespiration;Cotton

Received: 　　Accepted:

Corresponding author: 　　E-mail:

Citing This Article：

Guo Lianwang, Xu Daquan, Shen Yungang. The causes of widday decline of photosynthetic efficiency in cotton leaves under field coditions. Acta Physiol Sin 1994; 46 (4): (in Chinese with English abstract).