幼龄和成龄锯叶竹节树的光合特性

Photosynthetic Characteristics of Young and Mature Carallia diplopetala

比较研究了幼龄和成龄锯叶竹节树净光合速率对光强的响应特性及主要生理和环境因子的日变化进程。结果表明,成龄树的光饱和点(LSP)、光补偿点(LCP)、光饱和光合速率(Pmax)和表观量子效率(AQY)分别为836、6.18、9.52和0.047μmol.m-2.s-1;幼树的LSP、LCP、Pmax和AQY分别为359、2.79、5.05和0.036μmol.m-2.s-1。成龄树的Pmax和LSP较高,LCP较低,对强光和弱光的适应性均较强;幼树的Pmax、LSP、LCP和AQY均较低,对弱光的适应性强,但较低的光合能力和量子效率延长了锯叶竹节树的幼龄期。幼树和成龄树的环境最大光强均低于其LSP,其净光合速率日进程也均为单峰曲线,没有明显的"午休"现象;气孔导度和蒸腾速率的日变化趋势也均基本与Pn一致。在迁地保护时,应选择较为荫蔽的环境定植。

The responses of net photosynthetic rate（Pn） to the photon flux density（PFD） and the diurnal course of variation in major physiological and environmental variables of young and mature Carallia diplopetala were studied.The results showed that the light saturation point（LSP）,light compensation point（LCP）,maximum net photosynthetic rate（Pmax）,apparent quantum yield（AQY） of mature C.diplopetala was 836,6.18,9.52 and 0.047 μmol ·m-2·s-1,respectively.The Pmax,LSP,LCP and AQY of young C.diplopetala was 359,2.79,5.05 and 0.036 μmol·m-2·s-1,respectively.The mature C.diplopetala was adapted to high and low light intensity with high Pmax,LSP,and low LCP. The Pmax,LSP,LCP and AQY of young C.diplopetala were low, hence,the low photosynthesis and quanta effect kept the young period of C.diplopetala long.The environmental light intensity of both young and mature C.diplopetala were below their LSP.The diurnal variation of Pn was ＂single-peaked＂ curves with no ＂noon break＂.The diurnal variation in stomata conductance and transpiration rate of young and mature C.diplopetala were similar to the diurnal variation in Pn.Consequently,it should be planted in shade habitat in ex-situ conservation.