Genotype differences in 13C discrimination between atmosphere and leaf matter match differences in transpiration efficiency at leaf and whole-plant levels in hybrid Populus deltoides ×nigra

Authors

  • FAHAD RASHEED,

    1. INRA, UMR 1137 Ecologie et Ecophysiologie Forestières, F-54280 Champenoux, France
    2. INRA, USC1328 Arbres et Réponses aux Contraintes Hydriques et Environnementales (ARCHE), rue de Chartres, BP 6759, F-45067 Orléans Cedex 2, France
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  • ERWIN DREYER,

    Corresponding author
    1. INRA, UMR 1137 Ecologie et Ecophysiologie Forestières, F-54280 Champenoux, France
    2. Université de Lorraine, UMR 1137 Ecologie et Ecophysiologie Forestières, Faculté des Sciences, F-54500 Vandoeuvre-lès-Nancy, France
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  • BÉATRICE RICHARD,

    1. INRA, UMR 1137 Ecologie et Ecophysiologie Forestières, F-54280 Champenoux, France
    2. Université de Lorraine, UMR 1137 Ecologie et Ecophysiologie Forestières, Faculté des Sciences, F-54500 Vandoeuvre-lès-Nancy, France
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  • FRANCK BRIGNOLAS,

    1. Université d'Orléans, UFR-Faculté des Sciences, UPRES EA 1207 Laboratoire de Biologie des Ligneux et des Grandes Cultures (LBLGC), rue de Chartres, BP 6759, F-45067 Orléans Cedex 2, France
    2. INRA, USC1328 Arbres et Réponses aux Contraintes Hydriques et Environnementales (ARCHE), rue de Chartres, BP 6759, F-45067 Orléans Cedex 2, France
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  • PIERRE MONTPIED,

    1. INRA, UMR 1137 Ecologie et Ecophysiologie Forestières, F-54280 Champenoux, France
    2. Université de Lorraine, UMR 1137 Ecologie et Ecophysiologie Forestières, Faculté des Sciences, F-54500 Vandoeuvre-lès-Nancy, France
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  • DIDIER LE THIEC

    1. INRA, UMR 1137 Ecologie et Ecophysiologie Forestières, F-54280 Champenoux, France
    2. Université de Lorraine, UMR 1137 Ecologie et Ecophysiologie Forestières, Faculté des Sciences, F-54500 Vandoeuvre-lès-Nancy, France
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E. Dreyer. E-mail: dreyer@nancy.inra.fr

ABSTRACT

13C discrimination between atmosphere and bulk leaf matter (Δ13Clb) is frequently used as a proxy for transpiration efficiency (TE). Nevertheless, its relevance is challenged due to: (1) potential deviations from the theoretical discrimination model, and (2) complex time integration and upscaling from leaf to whole plant. Six hybrid genotypes of Populus deltoides×nigra genotypes were grown in climate chambers and tested for whole-plant TE (i.e. accumulated biomass/water transpired). Net CO2 assimilation rates (A) and stomatal conductance (gs) were recorded in parallel to: (1) 13C in leaf bulk material (δ13Clb) and in soluble sugars (δ13Css) and (2) 18O in leaf water and bulk leaf material. Genotypic means of δ13Clb and δ13Css were tightly correlated. Discrimination between atmosphere and soluble sugars was correlated with daily intrinsic TE at leaf level (daily mean A/gs), and with whole-plant TE. Finally, gs was positively correlated to 18O enrichment of bulk matter or water of leaves at individual level, but not at genotype level. We conclude that Δ13Clb captures efficiently the genetic variability of whole-plant TE in poplar. Nevertheless, scaling from leaf level to whole-plant TE requires to take into account water losses and respiration independent of photosynthesis, which remain poorly documented.

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