Journal Article

Growth and physiological responses of isohydric and anisohydric poplars to drought

Ziv Attia, Jean-Christophe Domec, Ram Oren, Danielle A. Way and Menachem Moshelion

in Journal of Experimental Botany

Volume 66, issue 14, pages 4373-4381
Published in print July 2015 | ISSN: 0022-0957
Published online May 2015 | e-ISSN: 1460-2431 | DOI: https://dx.doi.org/10.1093/jxb/erv195

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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.

Keywords: Bioenergy; biomass; carbon; hydraulic conductance; stomata; transpiration

Journal Article.  6601 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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