不同水分梯度下珍稀植物四数木的光合特性及对变化光强的响应  

Photosynthetic characteristics of an endangered species Tetrameles nudiflora under different light and water conditions

作　　者：邓云[1] 陈辉[1,2] 杨小飞[1] 许海龙 邓晓保[1] 李玉武[1,2] 陈本雄 张文富[1] 

机构地区：[1]中国科学院西双版纳热带植物园,勐仑666303 [2]中国科学院北京研究生院,北京100049 [3]西双版纳国家级自然保护区管理局勐腊管理所,勐腊666300 [4]普洱学院,普洱665000

出　　处：《生态学报》2013年第22期7088-7097,共10页Acta Ecologica Sinica

基　　金：中国科学院野外台站资助项目

摘　　要：四数木是东南亚热带森林的代表植物之一,但林下自然更新困难,为国家二级保护植物。对盆栽控水条件下的四数木幼苗为材料,重点讨论了四数木幼苗净光合速率(P n)、气孔导度(G s)、胞间CO2浓度(C i)、叶面水汽压亏缺(VPD)对光照强度(PAR)变化的响应。研究表明:四数木幼苗在各个水分梯度下的光饱和点(LSP)、最大净光合速率(P max)均较文献报道过的其他当地演替后期物种更高,光强突然由饱和光降至有限光时净光合速率(P n)变化成V型曲线,稳定光强下胁迫水分处理组净光合速率低于饱和处理组,但各水分梯度下四数木幼苗对光强变化的响应时间无明显差异。四数木应属阳性植物,林下郁闭生境并不利于其更新,但其成年植株较长的寿命和较高的层次可能使其在群落演替的整个过程中都对林下环境的维持具有持续性贡献。Tetrameles nudiflora is a representative species of the Southeast Asian rainforest and as its seedlings rarely survive in the understory, it was included in the protection category. Previous investigations found that the Tetrameles nudiflora seedling rarely survived in the understory, therefore it is hard to explain why the adults could grow into the top layer of the canopy in mature rainforests. In this study, we discussed the photosynthetic characteristics of the Tetrameles nudiflora seedling which varied under different light and water conditions. Our purpose was to confirm whether Tetrameles nudiflora was a heliophilous plant or not, and how it responded to drought stress, which would be very important for the in- situ and ex-situ protection of Tetrameles nudiflora in monsoon climate areas In this experiment, Tetrameles nudiflora seedlings have been treated under three different water supplies： water-saturated treatment （ ST）, （ 32.2± 8.3 ） % soil volumetric water content （ VWC ） ; control treatment （ CT）, （ 24.6 ± 7.7） % ; and drought treatment （DT）, （19.6±7.6）%. The results showed that Tetrameles nudiflora seedlings had a higher light saturation point （LSP） （726-1080 μmol m-2 s-1） and maximum photosynthetic rate （Pmax） （5.481--9.708 μmol CO2 m-2 s-1 ） than other species from later stages of succession, under all water gradients. The Pn response to PAR changed as the V-curve when the light changed from saturating to a more limited level. The net photosynthetic rate of water-saturated treatment （（9.515±3.216） μmol CO2 m-2 s-1） was higher than others in stable light （ 1500 μmol m-2 s-1） , but the time requirements of the net photosynthetic rate to stabilize from darkness to 1500 μmol m-2 S-1 were （6.9±0.7） min （ST）, （6.6±2.2） min （CT） and （7.5±1.4） min （DT）. The time requirements of net photosynthetic rate to stabilize from 1500μmol m-2 s-1 to 100 μmol m-2 s-1 were （5.6±0.8） min （ST）, （5.9±0.5） min �

关 键 词：四数木 光合特征 光强适应 水分梯度 

分 类 号：Q948[生物学—植物学]