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Clarifying the mechanisms underlying the recovery of gas exchange following drought is the key to providing insights into plant drought adaptation and habitat distribution. However, the mechanisms are still largely unknown. Targeting processes known to inhibit gas exchange during drought recovery, we measured leaf water potential, the leaf hydraulic conductance, stomatal reopening, abscisic acid (ABA) and the ethylene emission rate (EER) following moderate drought stress in seedlings of the globally pervasive woody tree Fraxinus chinensis. We found strong evidence that the slow stomatal reopening after rehydration is regulated by a slow decrease in EER, rather than changes in leaf hydraulics or foliar ABA levels. This was supported by evidence of rapid gas exchange recovery in plants after treatment with the ethylene antagonist 1-methylcyclopropene. These findings provide evidence to rigorously support ethylene as a key factor constraining stomatal reopening from moderate drought directly, thereby potentially opening new windows for understanding species drought adaptation. [ABSTRACT FROM AUTHOR]

Resprouting plants are distributed in many vegetation communities worldwide. With increasing resprout age post-severe-disturbance, new stems grow rapidly at their early age, and decrease in their growth with gradually decreasing water status thereafter. However, there is little knowledge about how stem hydraulic strategies and anatomical traits vary post-disturbance. In this study, the stem water potential (Ψ stem), maximum stem hydraulic conductivity (K stem-max), water potential at 50% loss of hydraulic conductivity (K stem   P 50) and anatomical traits of Caragana korshinkii resprouts were measured during a 1- to 13-year post-disturbance period. We found that the K stem-max decreased with resprout age from 1-year-old resprouts (84.2 mol m−1 s−1 MPa−1) to 13-year-old resprouts (54.2 mol m−1 s−1 MPa−1) as a result of decreases in the aperture fraction (F ap) and the sum of aperture area on per unit intervessel wall area (A ap). The K stem   P 50 of the resprouts decreased from 1-year-old resprouts (−1.8 MPa) to 13-year-old resprouts (−2.9 MPa) as a result of increases in vessel implosion resistance (t/b)2, wood density (WD), vessel grouping index (GI) and decreases in F ap and A ap. These shifts in hydraulic structure and function resulted in an age-based divergence in hydraulic strategies i.e. a change from an acquisitive strategy to a conservative strategy, with increasing resprout age post-disturbance. [ABSTRACT FROM AUTHOR]