Water is an important factor for potential carbon sequestration through photosynthetic effect.It has been a hotspot study for Ecology and Physiology how the epiphyte under long-term water stress environment uses effectively water to respond to water stress.In this paper,eight epiphytic Dendrobium species and five leaf traits related to water adaptation and the synergistic relationships among the traits were studied,aiming to discuss the water adaptive strategies of epiphytes in water stress environment.The results showed that correlations existed among these traits,indicating the synergistic relationships exist among leaf functions of water supply,water loss and water conservation.Vein density was significantly and positively correlated with stomata density,reflecting a leaf hydraulic balance between water supply and loss.Vein density presented significant and negative correlations with leaf thickness and mesophyll thickness(except for Dendrobium terminale),reflecting a trade-off between water supply and conservation.Consistently,the trade-off was also found between water conservation and photosynthetic water loss since there were significant and negative correlations between stomata density and leaf thickness/mesophyll thickness.The present research indicated that in the conditions of frequent water stress,epiphytes have closely relationships in water supply,water loss and water conservation,and this strategy may be an important physiological mechanism for epiphytes to effectively manage their water under natural selections.%水是利用光合作用进行潜在碳吸收的重要因子.生长在长期缺水环境下的附生植物如何有效地利用水分,以应对相对缺水环境是生态学和生理学研究的热点.本文通过研究8种附生石斛属植物5个与水分适应性相关的叶片性状,检测这些性状之间的协同关系,以探讨附生植物对缺水环境的水分适应机制.结果发现,这些叶片性状之间均存在相关性,表明叶片在其供水、失水和保水功能之间存在协调.叶脉密度与气孔密度吓死呈显著正相关,反映叶片的水力供需平衡.叶脉密度与叶片厚度、叶肉厚度间均存在极显著负相关(刀叶石斛除外),反映叶片供水和保水之间的权衡;与此趋势一致,气孔密度与叶片厚度、叶肉厚度间也均存在极显著负相关,反映叶片保水和光合失水之间的权衡.本研究表明,在经常发生缺水胁迫的情况下,附生植物在供水、失水和保水策略上密切关联,这种策略是附生植物在自然选择条件下进行有效地水分管理的重要生理机制.
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