title: Growth and physiological responses of isohydric and anisohydric poplars to drought.
abstract: Understanding how different plants prioritize carbon gain and drought vulnerability under a variable water supply is important for predicting which trees will maximize woody biomass production under different environmental conditions. Here, Populus balsamifera (BS, isohydric genotype), P. simonii (SI, previously uncharacterized stomatal behaviour), and their cross, P. balsamifera x simonii (BSxSI, anisohydric genotype) were studied to assess the physiological basis for biomass accumulation and water-use efficiency across a range of water availabilities. Under ample water, whole plant stomatal conductance (gs), transpiration (E), and growth rates were higher in anisohydric genotypes (SI and BSxSI) than in isohydric poplars (BS). Under drought, all genotypes regulated the leaf to stem water potential gradient via changes in gs, synchronizing leaf hydraulic conductance (Kleaf) and E: isohydric plants reduced Kleaf, gs, and E, whereas anisohydric genotypes maintained high Kleaf and E, which reduced both leaf and stem water potentials. Nevertheless, SI poplars reduced their plant hydraulic conductance (Kplant) during water stress and, unlike, BSxSI plants, recovered rapidly from drought. Low gs of the isohydric BS under drought reduced CO2 assimilation rates and biomass potential under moderate water stress. While anisohydric genotypes had the fastest growth under ample water and higher photosynthetic rates under increasing water stress, isohydric poplars had higher water-use efficiency. Overall, the results indicate three strategies for how closely related biomass species deal with water stress: survival-isohydric (BS), sensitive-anisohydric (BSxSI), and resilience-anisohydric (SI). Implications for woody biomass growth, water-use efficiency, and survival under variable environmental conditions are discussed.
authors.affiliation: Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Ziv
authors.initials: Z
authors.lastname: Attia
authors.affiliation: Bordeaux Sciences Agro UMR INRA-ISPA 1391, 33195, Gradignan, France Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27695, USA Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Domec
authors.affiliation: Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina 27708, USA Department of Forest Ecology & Management, Swedish University of Agricultural Sciences (SLU), SE-901 83, Umeå, Sweden.
authors.forename: Ram
authors.initials: R
authors.lastname: Oren
authors.affiliation: Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina 27708, USA Department of Biology, University of Western Ontario, London, ON, N6A 5B7, Canada dway4@uwo.ca.
authors.forename: Danielle A
authors.initials: DA
authors.lastname: Way
authors.affiliation: Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Menachem
authors.initials: M
authors.lastname: Moshelion
mesh_terms: D055864:Droughts; D032107:Populus / Q000254:growth & development / Q000502:physiology*
keywords: Bioenergy; biomass; carbon; hydraulic conductance; stomata; transpiration