Coordinated hydraulic traits influence the two phases of time to hydraulic failure in five temperate tree species differing in stomatal stringency

Waite Pierre-andré, Kumar Manish, Link Roman M., Schuldt Bernhard. 2024. Coordinated hydraulic traits influence the two phases of time to hydraulic failure in five temperate tree species differing in stomatal stringency. Tree Physiology, 44 (5):tpae038, 15 p.

Url - jeu de données - Entrepôt autre : https://doi.org/10.5281/zenodo.8117431

Résumé : Worldwide, forests are increasingly exposed to extreme droughts causing tree mortality. Because of the complex nature of the mechanisms involved, various traits have been linked to tree drought responses with contrasting results. This may be due to species-specific strategies in regulating water potential, a process that unfolds in two distinct phases: a first phase until stomatal closure, and a second phase until reaching lethal xylem hydraulic thresholds. We conducted dry-down experiments with five broadleaved temperate tree species differing in their degree of isohydry to estimate the time to stomatal closure (tsc) and subsequent time to critical hydraulic failure (tcrit). We measured various traits linked to tree drought responses, such as the water potentials at turgor loss point (Ptlp), stomatal closure (Pgs90), and 12%, 50% and 88% loss of xylem hydraulic conductance (P12, P50, P88), hydraulic capacitance (C), minimum leaf conductance (gmin), hydroscape area (HSA) and hydraulic safety margins (HSM). We found that Pgs90 followed previously recorded patterns of isohydry and was associated with HSA. Species ranked from more to less isohydric in the sequence Acer pseudoplatanus < Betula pendula < Tilia cordata < Sorbus aucuparia < Fagus sylvatica. Their degree of isohydry was associated with leaf safety (Ptlp and gmin), drought avoidance (C) and tsc, but decoupled from xylem safety (HSM and P88) and tcrit. Regardless of their stomatal stringency, species with wider HSM and lower P88 reached critical hydraulic failure later. We conclude that the duration of the first phase is determined by stomatal regulation, while the duration of the second phase is associated with xylem safety. Isohydry is thus linked to water use rather than to drought survival strategies, confirming the proposed use of HSA as a complement to HSM for describing plant drought responses before and after stomatal closure.

Mots-clés Agrovoc : résistance à la sécheresse, sécheresse, potentiel xylème eau, réponse de la plante, tolérance à la sécheresse, Betula pendula, Acer pseudoplatanus, Tilia cordata, Fagus sylvatica, xylème, conductance stomatique, Sorbus aucuparia, Acer, Betula, Tilia, Sorbus, Fagus, potentiel hydrique

Mots-clés libres : Anisohydry, Capacitance, Cuticular conductance, Desiccation time, Hydraulic safety margin, Hydroscape area, Stomatal closure, Water potential regulation

Classification Agris : F60 - Physiologie et biochimie végétale

Champ stratégique Cirad : CTS 2 (2019-) - Transitions agroécologiques

Agences de financement hors UE : Indian Council of Agricultural Research, Bundesministerium für Ernährung und Landwirtschaft, Bundesministerium für Umwelt, Naturschutz, nukleare Sicherheit und Verbraucherschutz, Fachagentur Nachwachsende Rohstoffe

Projets sur financement : (DEU) NONNATIVE

Auteurs et affiliations

• Waite Pierre-andré, CIRAD-PERSYST-UPR AIDA (FRA) ORCID: 0000-0003-2606-4304 - auteur correspondant
• Kumar Manish, University of Würzburg (DEU) - auteur correspondant
• Link Roman M., University of Würzburg (DEU)
• Schuldt Bernhard, University of Würzburg (DEU)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/609232/)

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