title: A simple framework to analyze water constraints on seasonal transpiration in rubber tree (Hevea brasiliensis) plantations.
abstract: Climate change and fast extension in climatically suboptimal areas threaten the sustainability of rubber tree cultivation. A simple framework based on reduction factors of potential transpiration was tested to evaluate the water constraints on seasonal transpiration in tropical sub-humid climates, according pedoclimatic conditions. We selected a representative, mature stand in a drought-prone area. Tree transpiration, evaporative demand and soil water availability were measured every day over 15 months. The results showed that basic relationships with evaporative demand, leaf area index and soil water availability were globally supported. However, the implementation of a regulation of transpiration at high evaporative demand whatever soil water availability was necessary to avoid large overestimates of transpiration. The details of regulation were confirmed by the analysis of canopy conductance response to vapor pressure deficit. The final objective of providing hierarchy between the main regulation factors of seasonal and annual transpiration was achieved. In the tested environmental conditions, the impact of atmospheric drought appeared larger importance than soil drought contrary to expectations. Our results support the interest in simple models to provide a first diagnosis of water constraints on transpiration with limited data, and to help decision making toward more sustainable rubber plantations.
authors.affiliation: Department of Plant Science, Faculty of Natural Resources, Prince of Songkla University Songkhla, Thailand.
authors.forename: Jessada
authors.initials: J
authors.lastname: Sopharat
authors.affiliation: UMR Eco&Sols, French Agricultural Research Centre for International Development (CIRAD) Montpellier, France ; Hevea Research Platform in Partnership, DORAS Centre, Kasetsart University Bangkok, Thailand.
authors.forename: Frederic
authors.initials: F
authors.lastname: Gay
authors.affiliation: UMR Eco&Sols, French Agricultural Research Centre for International Development (CIRAD) Montpellier, France ; Hevea Research Platform in Partnership, DORAS Centre, Kasetsart University Bangkok, Thailand.
authors.forename: Philippe
authors.initials: P
authors.lastname: Thaler
authors.affiliation: Department of Plant Science, Faculty of Natural Resources, Prince of Songkla University Songkhla, Thailand.
authors.forename: Sayan
authors.initials: S
authors.lastname: Sdoodee
authors.affiliation: Department of Plant Science and Agricultural Resources, Faculty of Agriculture, Khon Kaen University Khon Kaen, Thailand.
authors.forename: Supat
authors.initials: S
authors.lastname: Isarangkool Na Ayutthaya
authors.affiliation: Department of Earth Science, Faculty of Natural Resources, Prince of Songkla University Songkhla, Thailand.
authors.forename: Charlchai
authors.initials: C
authors.lastname: Tanavud
authors.affiliation: UMR Eco&Sols, Institut de Recherche pour le Développement Montpellier, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Hammecker
authors.affiliation: UMR Eco&Sols, Institut de Recherche pour le Développement Montpellier, France.
authors.forename: Frederic C
authors.initials: FC
authors.lastname: Do
keywords: canopy phenology; drought; high evaporative demand; potential transpiration model; relative extractable soil water