不同光环境下东北红豆杉幼树叶光合和荧光特性比较

Comparison of photosynthetic and fluorscence characteristics of leaves in Taxus cuspidata under different light intensities

为了解东北红豆杉对光强的适应性,以15年生东北红豆杉幼树为材料,研究了生长在不同光环境下东北红豆杉幼树叶片光合特性以及叶绿素荧光特性。结果表明:弱光条件下生长的东北红豆杉幼树叶片光合速率较低,是自然光下生长叶片的60%,并且羧化效率较低,表现出阴生叶片的特点。光强由弱光转换强光时,弱光叶片和自然光叶片实际光化学效率(ΦPSⅡ)、电子传递速率(ETR)和非光化学淬灭(NPQ)有显著差异。随光强的增加弱光叶片ΦPSⅡ下降幅度较大,而自然光照下生长的叶片下降幅度较小;弱光叶片ETR小于自然光叶片;弱光和自然光叶片的NPQ随光强的升高而升高,但弱光叶片在较低光强下即达到最大值。弱光叶片虽然色素含量较高,但是Chl a/Chl b比值较低,且电子传递速率和实际光化学效率较低,适应阴生环境。弱光叶片较低的光合速率以及过剩光能耗散能力较低是其转入强光后光抑制严重的主要原因。

To further explain acclimation in Taxus cuspidata to light intensity, taking 15-year-old saplings in T. cuspidata as materials, photosynthetic and chloropphyll fluorescence characteristics were studied under different light intensities. The results showed that compared with the salings in T. cuspidata planted in full light, the leaves planted in weak light had lower photosynthetic rate, which was 60% of the value of leaves planted in full light, and lower carboxylation efficiency, so they had the characteristics in shade leaves. Actual photochemical efficiency （~Ps II ） , electron transport rate（ETR）and non-photochemical quenching （NPQ） had significant differences between the leaves in weak light and full light, when light intensities was transferred from weak to strong. As light intensity increasing, decreased range of ~~PSH of leaves in weak light was higher, ETR of leaves in weak light was lower than that in full light. NPQ of leaves in weak light and full light was increased with light intensity rising, but the index of leaves in weak light could reach the peak value under lower light intensity. Leaves in weak light had higher chlorophyll content, lower ratio of Chl a to Chl b, and lower ETR and φPsⅡ, indicating their shade-environmental acclimation. Lower photosynthetic rate and excess light energy dissipation ability in leaves in weak light were the main reason of serious photo inhibition after transferred to strong light.