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

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.