Leaf trichomes of Dendrobium species (epiphytic orchids) in relation to foliar water uptake, leaf surface wettability, and water balance

• Published in: Environmental and experimental botany 2021-10, Vol.190, p.104568, Article 104568
• Main Authors: Pan, Zhi-Li, Guo, Wen, Zhang, Yong-Jiang, Schreel, Jeroen D.M., Gao, Jiang-Yun, Li, Yong-Ping, Yang, Shi-Jian
• Format: Article
• Language: English
• Subjects: Contact angle; Dendrobium; Epiphytic adaptation; Foliar water uptake; Stomatal traits; Trichome density
• ISSN: 0098-8472; 1873-7307
• DOI: 10.1016/j.envexpbot.2021.104568

•The epiphytic species with trichomes show a higher percentage increase in leaf water content.•The trichome density is closely related to stomatal traits, but not with leaf water loss rates.•The epiphytic species with trichomes dries faster from saturated leaves to 70 % relative water content.•A potential trade-off exists between leaf water absorption and conservation in epiphytic species.•Different water use strategies are utilized by the leaves of epiphytic orchids with and without trichomes. Vascular epiphytes play an important role in the water and carbon cycles of forest ecosystems. While trichomes are found on the leaf surface of many epiphytic species, few studies have investigated the effect of leaf trichomes on their foliar water uptake, leaf surface wettability, and water balance. In our study, leaf water absorption, storage, and retention capacities, as well as leaf surface wettability of twelve Dendrobium species with glabrous (n = 6) and piliferous (n = 6) leaves were investigated and related to their leaf morphological and anatomical characteristics. Our results showed that no significant difference in foliar water uptake capacity was found between groups with different leaf surface types (with and without trichomes). However, the piliferous Dendrobium species showed a significantly larger increase in leaf water content (%LWC) and lower values for both saturated water content per unit mass and water retention capacity compared to glabrous ones. Across Dendrobium species with piliferous leaves, the trichome density on leaf abaxial surface was positively correlated with foliar water uptake capacity per unit area, contact angle, stomatal density and stomata area per unit index. Besides, species with a higher %LWC after leaf immersion dried faster from saturated leaves to a relative water content of 70 %, which suggests a potential trade-off between leaf water absorption and conservation in epiphytic Dendrobium species. The variation in leaf water absorption and conservation suggests that different water use strategies are utilized by epiphytic orchids with glabrous and piliferous leaves.