Department of Plant Biology, Institute of Biology, University of Campinas - UNICAMP, CP6109, Campinas, São Paulo, Brazil.
New Phytol. 2013 Jul;199(1):151-162. doi: 10.1111/nph.12248. Epub 2013 Mar 28.
Foliar water uptake (FWU) is a common water acquisition mechanism for plants inhabiting temperate fog-affected ecosystems, but the prevalence and consequences of this process for the water and carbon balance of tropical cloud forest species are unknown. We performed a series of experiments under field and glasshouse conditions using a combination of methods (sap flow, fluorescent apoplastic tracers and stable isotopes) to trace fog water movement from foliage to belowground components of Drimys brasiliensis. In addition, we measured leaf water potential, leaf gas exchange, leaf water repellency and growth of plants under contrasting soil water availabilities and fog exposure in glasshouse experiments to evaluate FWU effects on the water and carbon balance of D. brasiliensis saplings. Fog water diffused directly through leaf cuticles and contributed up to 42% of total foliar water content. FWU caused reversals in sap flow in stems and roots of up to 26% of daily maximum transpiration. Fog water transported through the xylem reached belowground pools and enhanced leaf water potential, photosynthesis, stomatal conductance and growth relative to plants sheltered from fog. Foliar uptake of fog water is an important water acquisition mechanism that can mitigate the deleterious effects of soil water deficits for D. brasiliensis.
叶面水分吸收（FWU）是温带雾生生态系统中植物常见的水分获取机制，但对于热带云雾林物种的水分和碳平衡而言，这种过程的普遍性和后果尚不清楚。我们在野外和温室条件下使用一系列方法（液流、荧光质外示踪剂和稳定同位素）进行了一系列实验，以追踪雾水从叶面到 Drimys brasiliensis 地下部分的移动。此外，我们在温室实验中测量了不同土壤水分供应和雾暴露下植物的叶片水势、叶片气体交换、叶片疏水性和生长情况，以评估 FWU 对 D. brasiliensis 幼苗水分和碳平衡的影响。雾水直接通过叶片角质层扩散，最高可达叶片含水量的 42%。FWU 导致茎和根中的液流发生了高达每日最大蒸腾量 26%的逆转。通过木质部输送的雾水到达地下蓄水层，并提高了叶片水势、光合作用、气孔导度和生长，与免受雾影响的植物相比。叶面吸收雾水是一种重要的水分获取机制，可以减轻 Drimys brasiliensis 土壤水分亏缺的有害影响。
