Foliar water uptake in eight mangrove species: Implications of morpho-anatomical traits

Abstract

There is growing evidence that foliar water uptake (FWU) positively contributes to the water status of plants. However, the morpho-anatomical traits and the mechanisms responsible for variations in FWU of mangrove leaves are poorly understood. We evaluated the relationship between FWU and morpho-anatomical traits in eight mangrove species (Avicennia germinans, A. marina, A. schaueriana, Bruguiera gymnorhiza, Conocarpus erectus, Laguncularia racemosa, Rhizophora mangle, R. mucronata). FWU was measured in leaves experimentally submerged in distilled water and was related to morphological and anatomical traits using a Principal Component Analysis (PCA). There were inter-species differences in FWU, with L. racemosa and A. schaueriana having the highest values, and B. gymnorhiza and R. mucronata having the lowest. Three groups associated at the family level were found based on morpho-anatomical attributes: (1) greater thickness of the abaxial epidermis and specific leaf area (L. racemosa and C. erectus; Combretaceae); (2) presence of trichomes and salt glands and thicker palisade parenchyma (A. germinans, A. marina, and A. schaueriana; Acanthaceae), both families with relatively high FWU; and (3) higher leaf dry mass, leaf area, and thicker hypodermis (B. gymnorhiza and R. mucronata; Rhizophoraceae), but lower FWU. Our results suggest that mangrove species take up atmospheric water at different rates and strategies that depend on morpho-anatomical traits, suggesting its differential use as a supplementary resource.