不同光强下核桃楸、水曲柳和黄菠萝的光合生理特征

Photosynthetic Characteristics of Juglans mandshurica,Fraxinus mandshurica and Phellodendron amurense under Different Light Regimes

研究辽东山区次生林3种树种幼苗(核桃楸、水曲柳和黄菠萝)对生长光环境的适应性,在生长季测定4种光强下(全光、60%透光、30%透光、15%透光,分别记为FI,II,LI和WI)树种幼苗叶片气体交换参数、净光合速率、单位叶面积叶绿素含量和比叶重(LMA)。结果表明:随着光强的减弱,3个树种的光补偿点(LCP)、光饱和点(LSP)、最大光合速率(Pmax)、暗呼吸速率(Rd)、类胡萝卜素(Car)、LMA、单位叶鲜质量(LFA)均呈下降趋势;全光下单位叶面积的叶绿素Chl含量均低于弱光处理。本研究结果支持水曲柳在幼苗时期具有一定耐荫性的观点。树种生理生态指标的可塑性分析表明:黄菠萝能适应更宽的光强幅度,且黄菠萝的需光性大于核桃楸。不同光环境下3个树种的生理生态变化特征对解释森林生态系统内树种的共生和演替具有重要意义。

The acclimation of seedlings of three secondary-forest tree species to light regimes was investigated during the growth season in 2007 in the Northeast of China. The seedlings of Juglans mandshurica,Fraxinus mandshurica and Phellodendron amurense were cultivated under four light intensity regimes（100%,60%,30% and 15% of full light,which were termed as FI,II,LI and WI respectively） . The photosynthetic characteristics,leaf mass per unit area,and chlorophyll content were determined during the growth season. The results showed that light compensation point （ LCP）, light saturation point （ LSP）,dark respiration rate （ Ra）, maximum photosynthetic rate （ Pmax ） . The content of carotenoid, leaf dry mass per unit leaf avea （LMA） of all the three tree species decreased along with decreasing light intensities. And the contents of chlorophyll （Chl） of full light treatment were lower than that of the others for all the tree species. The results suggested that Fraxinus mandshurica was moderately shade tolerant at the seedling stage. Analysis of the plasticity index of eco-physiological parameters, suggested that P. amurense had the ability of adapting to wider light intensity range ; and the ability of shade-intolerance for P. amurense was greater than that of Juglans mandshurica. The different adapting characters of eco-physiology to light regimes played an important role in explaining the mechanism of co-existing and succession of different species in secondary forest ecosystem.