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Common trade-offs between xylem resistance to cavitation and other physiological traits do not hold among unrelated Populus deltoides ×Populus nigra hybrids

Authors

  • RÉGIS FICHOT,

    1. Université d'Orléans, UFR-Faculté des Sciences, UPRES EA 1207 Laboratoire de Biologie des Ligneux et des Grandes Cultures (LBLGC), BP 6759, F-45067, France,
    2. INRA, USC2030 Arbres et Réponses aux Contraintes Hydrique et Environnementales (ARCHE), BP 6759, F-45067, France,
    3. INRA UR588 Amélioration, Génétique et Physiologie Forestières (AGPF), Centre de Recherche d'Orléans, CS 40001 Ardon, F-45075, Orléans Cedex 2, France,
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  • TÊTÈ S. BARIGAH,

    1. UMR547 Physiologie Intégrée de l'Arbre Fruitier (PIAF), INRA-Université Blaise Pascal, F-63100, Clermont-Ferrand, France and
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  • SYLVAIN CHAMAILLARD,

    1. Université d'Orléans, UFR-Faculté des Sciences, UPRES EA 1207 Laboratoire de Biologie des Ligneux et des Grandes Cultures (LBLGC), BP 6759, F-45067, France,
    2. INRA, USC2030 Arbres et Réponses aux Contraintes Hydrique et Environnementales (ARCHE), BP 6759, F-45067, France,
    3. INRA UR588 Amélioration, Génétique et Physiologie Forestières (AGPF), Centre de Recherche d'Orléans, CS 40001 Ardon, F-45075, Orléans Cedex 2, France,
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  • DIDER LE THIEC,

    1. INRA, UMR1137 Ecologie et Ecophysiologie Forestières, Nancy Universités, IFR110 Génomique, Ecophysiologie, Ecologie Fonctionnelle, F-54280, Champenoux, France
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  • FRANÇOISE LAURANS,

    1. INRA UR588 Amélioration, Génétique et Physiologie Forestières (AGPF), Centre de Recherche d'Orléans, CS 40001 Ardon, F-45075, Orléans Cedex 2, France,
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  • HERVÉ COCHARD,

    1. UMR547 Physiologie Intégrée de l'Arbre Fruitier (PIAF), INRA-Université Blaise Pascal, F-63100, Clermont-Ferrand, France and
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  • FRANCK BRIGNOLAS

    Corresponding author
    1. Université d'Orléans, UFR-Faculté des Sciences, UPRES EA 1207 Laboratoire de Biologie des Ligneux et des Grandes Cultures (LBLGC), BP 6759, F-45067, France,
    2. INRA, USC2030 Arbres et Réponses aux Contraintes Hydrique et Environnementales (ARCHE), BP 6759, F-45067, France,
      F. Brignolas. Fax: +33 (0)2 38 49 49 11; e-mail: franck.brignolas@univ-orleans.fr
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F. Brignolas. Fax: +33 (0)2 38 49 49 11; e-mail: franck.brignolas@univ-orleans.fr

ABSTRACT

We examined the relationships between xylem resistance to cavitation and 16 structural and functional traits across eight unrelated Populus deltoides×Populus nigra genotypes grown under two contrasting water regimes. The xylem water potential inducing 50% loss of hydraulic conductance (Ψ50) varied from −1.60 to −2.40 MPa. Drought-acclimated trees displayed a safer xylem, although the extent of the response was largely genotype dependant, with Ψ50 being decreased by as far as 0.60 MPa. At the tissue level, there was no clear relationship between xylem safety and either xylem water transport efficiency or xylem biomechanics; the only structural trait to be strongly associated with Ψ50 was the double vessel wall thickness, genotypes exhibiting a thicker double wall being more resistant. At the leaf level, increased cavitation resistance was associated with decreased stomatal conductance, while no relationship could be identified with traits associated with carbon uptake or bulk leaf carbon isotope discrimination, a surrogate of intrinsic water-use efficiency. At the whole-plant level, increased safety was associated with higher shoot growth potential under well-irrigated regime only. We conclude that common trade-offs between xylem resistance to cavitation and other physiological traits that are observed across species may not necessarily hold true at narrower scales.

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