遮阴对富贵草光合特性的影响

Effects of Shading on Photosynthetic Characteristics of Pachysandra terminalis

在遮阴0(CK)、50%、70%、90%4种光照条件下,对常绿灌木富贵草(Pachysandra terminalis)的光合特性进行研究。结果表明:随着遮阴度的增加,富贵草的光补偿点(LC,P)、光饱和点(LS,P)和暗呼吸速率(Rd)均下降,而日均净光合速率、最大净光合速率(Pmax)和表观量子效率(AQ,Y)均上升;叶片的净光合速率日变化均呈现先升高后降低再升高最后降低的变化规律,表现出明显的光合"午休"现象。遮阴50%、70%、90%3处理间富贵草的日均净光合速率并没有显著性差异(P>0.05),但三者与CK相比差异均达到极显著水平(P<0.01)。在遮阴50%、70%、90%条件下,富贵草的LC,P和Rd均较低,LS,P较高;CK条件下,LC,P、LS,P、Rd与其他处理相比极显著升高(P<0.01),而AQ,Y和Pmax则极显著降低(P<0.01)。综合可知,富贵草在遮阴50%～90%的光环境中均能生长良好,是一种优良的常绿地被植物。

An experiment was conducted to study the photosynthetic characteristics of an evergreen dwarf shrub P. terminalis un- der the light shading rate of 0% （CK）, 50%, 70% and 90%, respectively. With the aggravation of shading rate, the light compensation point （Lc,p ）, the light saturation point （ Lsp ） and the dark respiratory rate （ Rd ） of P. terminalis de- crease, the maximum net photosynthetic rate （Pmax）, the daily average net photosynthetic rate and apparent quantum yield （AQY） increase. The variation of net photosynthetic rate shows a fluctuation of upward tendency followed by downward,upward, and finally back to downward tendency with a significant midday depression of photosynthesis. There is no signifi- cant difference （P〉0.05） for the daily average net photosynthetic rate between 50%, 70% and 90% shading treatments, and there is significance level （P〈0.01） between above treatments and CK. The Lcp and Rd under 50% , 70% and 90% shading treatments are relatively lower, while the Lsp is relatively higher than that under CK. The Lcp, Lsp and Rd of CK are significantly increased （P〈0.01）, while AQY and Pmax are significantly decreased compared with those under other treatments （ P〈0.01 ）. Therefore, P. terminalis can grow well under 50% -90% shading conditions, and it is a fine ever- green ground cover plant.