夜间变暖提高荫香叶片的光合能力

研究了不同氮供应的条件下夜间变暖对荫香叶片光合能力的影响。当植株生长在相同的日间温度(25℃),而夜间温度从18℃增至20℃时,叶片的光合速率增高(p<0.05)。高氮供应的植株,夜间变暖下其叶片光合速率较低氮供应的高,氮供应增高能促进夜间变暖提高叶片光合速率的效应。在低氮供给和夜间变暖下,植株叶片的光下呼吸和暗呼吸的增高显著(p<0.05)。无论在高氮或低氮供应下,生长在夜间变暖下的植物,其叶片的R ub isco最大羧化速率(Vcm ax)和光合电子传递最大速率(Jm ax)增高(p<0.05),氮供应能增强夜间变暖对Vcm ax和Jm ax的正向效应。夜间变暖降低植株叶片的比叶重,而增加单位叶干重的氮含量(Nm),单位叶面积的氮含量(Na)没发生明显变化。随着全球气候变化,夜间趋暖将有利于树木叶片光合能力的提高,结合高氮供给将会明显地增高植物的碳固定。

Night-time warming increases photosynthetic capacity of sapling leaf of Cinna-(momum) burmanni grown with different nitrogen supplies

A study was conducted to examine the influence of night-time warming on leaf photosynthetic capacity of Cinnamomum burmanni under different levels of nitrogen supply. When daytime temperature was kept at 25C and the nighttime temperature raised from 18 to 20C, leaf photosynthetic rate of plants increased (p＜0. 05). Plants growing under high night-time temperature and treated with higher nitrogen supply had higher photosynthetic rate than those with lower nitrogen supply. The increments of light and dark respirations in leaves of plant growing under higher night-time temperature and treated with lower nitrogen supply were significant (p＜0.05) compared with those under lower night-time temperature. At both levels of nitrogen supply, the maximum rate of carboxylation catalyzed by Rubisco (V ) and the maximum rate of electron transport (Jmax) of leaf were stimulated when the plant grew under night-time warming (p＜0.05), and nitrogen intensified the increasing effect of night-time warming on V and J Night-time warming reduced specific leaf weight, but increased leaf nitrogen content based on dry weight (Nm), and no similar changes in leaf nitrogen content based on leaf area (Nα) were found. Therein, the future global climate change and night-time warming would be in favor of the enhancement of leaf photosynthetic capacity of the plants that have similar physiological characteristics in South China, and their effect together with higher nitrogen supply would significantly increase carbon fixation.