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title: 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
Other Title: Photosynthetic characteristics of an endangered species Tetrameles nudiflora under different light and water conditions
author: 邓云;  陈辉;  杨小飞;  许海龙;  邓晓保;  李玉武;  陈本雄;  张文富
Issued Date: 2013
Abstract: 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CO_2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。
English Abstract: 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), (32.28.3)% soil volumetric water content (VWC); control treatment (CT), (24.67.7)%; and drought treatment (DT), (19.67.6)%. The results showed that Tetrameles nudiflora seedlings had a higher light saturation point (LSP) (726-1080 mumol m~(-2) s~(-1)) and maximum photosynthetic rate (P_(max)) (5.481-9.708 mumol CO_2 m~(-2) s~(-1)) than other species from later stages of succession, under all water gradients. The P_n 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 ((9.5153.216) mumol CO_2 m~(-2) s~(-1)) was higher than others in stable light (1500 mumol m~(-2) s~(-1)), but the time requirements of the net photosynthetic rate to stabilize from darkness to 1500 mumol m~(-2) s~(-1) were (6.90.7) min (ST), (6.62.2) min (CT) and (7.51.4) min (DT). The time requirements of net photosynthetic rate to stabilize from 1500 mumol m~(-2) s~(-1) to 100 mumol m~(-2) s~(-1) were (5.60.8) min (ST), (5.90.5) min (CT) and (4.71.7) min (DT). The response time of photosynthetic acclimation to light changes had little change over all water gradients. In conclusion, the high LSP and P_(max) of Tetrameles nudiflora supports our hypothesis that it is a heliophilous species. The Tetrameles nudiflora seedling could grow faster than other local species in both the rainy and dry seasons with sufficient sunlight, and photosynthetic acclimation characteristics to light changes indicated this species was probably an early successional species. The Tetrameles nudiflora seedling rarely survived under a closed canopy, therefore the adults in a closed forest may have been established in the very early stages of community succession, long ago. The regeneration of the Tetrameles nudiflora population probably depends on the existence of large canopy gaps and secondary bare land. The higher photosynthesis and growth characteristics enable Tetrameles nudiflora to quickly close the forest and form the understory environment under which the Tetrameles nudiflora adults may contribute to the establishment of late successional species.
Department: 其他
Source: 生态学报
Content Type: 期刊论文
ISSN: 1000-0933
Language: 中文
Appears in Collections:支撑系统_期刊论文

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Recommended Citation:
邓云,陈辉,杨小飞,等. 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[J]. 生态学报,2013,33(22):7088-7097.
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