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Déterminismes physiologiques, morphologiques et moléculaires de l’efficience d’utilisation de l’eau en lien avec la réponse à la sécheresse chez les peupliers : de la feuille à la plante entière

Abstract : The number of drought events is expected to increase in intensity and frequency as a result of climate change. Since poplar productivity is closely linked to water availability, there is an increasing risk of decline in wood production from poplar plantations. Optimization of the ratio of biomass production to water used (i.e. water use efficiency, WUE) appears therefore as a relevant target for poplar research. Previous studies have shown the clonal diversity of WUE in poplar is driven mainly by stomatal conductance (gs). However gs and photosynthesis are not always tightly coupled which can result in large variations of WUE at leaf level. Additionally, because transpiration efficiency (TE) is laborious to measure, experiments are often conducted in pots in glasshouses. However in controlled conditions the environment is widely different than in the field and comparisons of WUE in controlled and field conditions are scarce in the literature. We assessed the diversity of stomatal dynamics among poplar genotypes under control or drought conditions grown in a glasshouse and in the field. We investigated the link between physiological, morphological and molecular factors and stomatal dynamics, and their influence on TE. Furthermore, we examined the relation between different estimators of WUE and its components between controlled and field conditions. Element content and candidate gene expression in the guard cells were also quantified at two times during the day to analyze their link to stomatal conductance. We found among the four genotypes studied significant genotypic variability of stomatal dynamics to irradiance and VPD which was altered by drought and growing conditions. Stomatal size and density as well as water use, but not WUE, were correlated to stomatal dynamics, emphasizing the importance and complexity of such mechanisms at the whole plant scale. Good agreements between leaf-level and whole-plant WUE among genotypes and between growing conditions were also found. Finally, distinct guard cell element contents and candidate gene expression, between leaf sides and time of day, linked with stomatal conductance draw attention to the diversity of components contributing to TE. These findings provides valuable information to better understand the diverse, sometimes unsuspected, leaf-level mechanisms driving water use efficiency at the whole plant scale.
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Theses
File URL :
http://docnum.univ-lorraine.fr/ulprive/DDOC_T_2019_0082_DURAND.pdf
Complete list of metadatas

https://hal.univ-lorraine.fr/tel-02350625
Contributor : Thèses Ul <>
Submitted on : Wednesday, November 6, 2019 - 9:34:10 AM
Last modification on : Tuesday, March 17, 2020 - 1:48:41 AM

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  • HAL Id : tel-02350625, version 1

Citation

Maxime Durand. Déterminismes physiologiques, morphologiques et moléculaires de l’efficience d’utilisation de l’eau en lien avec la réponse à la sécheresse chez les peupliers : de la feuille à la plante entière. Ingénierie de l'environnement. Université de Lorraine, 2019. Français. ⟨NNT : 2019LORR0082⟩. ⟨tel-02350625⟩

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