西双版纳地区附生与非附生植物叶片角质层对水分的透性研究

Cuticular Water Permeability of Leaves of Epiphytic and Non-epiphytic Species in Xishuangbanna Areas

摘要:

为了探讨雾水对西双版纳地区不同类型植物的生态学效应，干季于20℃及30℃下用自制的设备测定了西双版纳地区4种附生和4种非附生植物叶片上表皮水分进出角质层的透性，比较研究了不同类型植物叶片通过角质层蒸腾失水速率（P_T）、叶片通过角质层吸水速率（P_A）以及吸水与失水速率的比值（R=P_A/P_T）高低，及其与生活方式的关系。结果表明，附生植物的R值都高于非附生植物且大于1，说明附生植物通过叶片吸收的水分大于蒸腾失水，雾水对于附生植物具有更重要的生态学意义；P_T和P_A在不同植物间有显著差异，这可能与不同植物的角质层化学成分和物理结构不同有关，对其适应各自生活方式及多雾环境有重要意义。除附生植物贝母兰（Coelogyne occultata）和掌唇兰（Staurochilus dawsonianus）以及非附生植物大叶藤黄（Garcinia xanthochymus）外，30℃下其余植物的P_T和P_A都显著高于20℃的，说明温度对角质层的透性具有一定的影响。因此，雾水可能是该地区附生植物干季一种重要的水资源，雾水对附生植物的重要性大于对非附生植物的重要性。

Abstract:

Epiphyte is a special phytogroup in tropical rainforest, which live in stones or stems of other plants, and can not directly absorb water from the soil. In order to know whether cuticular transpiration of the epiphytes is lower or more fog (dew) can enter their leaves through cuticles compared to non-epiphytes. Four epiphytes and four non-epiphytes were selected to determine cuticular permeability of transpiration (P_T), cuticular permeability of water absorption (P_A) and the ratio of P_A/P_T (R) in Xishuangbanna Tropical Botanical Garden of Chinese Academy of Science. The results showed that R was higher for epiphytic leaves (R>1) than non-epiphytic leaves, indicating that epiphytes absorb more water than water loss through leaf cuticle, and fog had a more important ecological significance for epiphytes than non-epiphytes. P_T and P_A were different among plants, and might relate with the chemical composition and physical structure. Except for Coelogyne occultata, Staurochilus dawsonianus and Garcinia xanthochymus, P_T and P_A under 30℃ were higher than those undern 20℃, which indicated that temperature could play a crucial role in cuticular permeability. Therefore, it was indicated that fog might be an important water resources for epiphytes in Xishuangbanna, and play more important role in adaptation to dry season for epiphytes than for non-epiphytes.