Gamon J A, Pearcy R W
Department of Botany, University of California, 95616, Davis, CA, USA.
Oecologia. 1989 Jun;79(4):475-481. doi: 10.1007/BF00378664.
Gas exchange and chlorophyll fluorescence techniques were used to evaluate the hypothesis that leaf movement in Vitis californica Benth. (California wild grape) allows a compromise between sunlight interception and stress damage in order to maximize photosynthetic carbon gain over the life of the leaf. Leaves that were restrained horizontally tolerated their increased radiation loads if critical temperatures were not exceeded. Reductions in photosynthetic capacity and the F /F fluorescence ratio only occurred in leaves that attained high temperatures. Leaf orientation and canopy position were important determinants of leaf temperature. These results indicate that excessive leaf temperature, not high PFD, can be a principle cause of reduced carbon gain and senescence in this species in the wild. Leaf movement appears to protect photosynthetic components in midsummer.
加州葡萄（Vitis californica Benth.）的叶片运动能够在阳光截获和胁迫损伤之间达成妥协，从而在叶片的整个生命周期内使光合碳同化量最大化。如果不超过临界温度，水平束缚的叶片能够耐受增加的辐射负荷。光合能力和F/F荧光比率的降低仅发生在温度较高的叶片中。叶片方向和冠层位置是叶片温度的重要决定因素。这些结果表明，在野外，过高的叶片温度而非高光量子通量密度可能是该物种碳同化量减少和衰老的主要原因。叶片运动似乎在仲夏时节保护光合组件。
