The resistance of different genotypes to abiotic stress may be due to genetic effects and/or to phenotypic plasticity allowing them to acclimate to variable conditions. The contribution of one or the other mechanism determines different strategies with implications for the species conservation and adaptive management. In this study, the ecophysiological response to drought of Nothofagus pumilio provenance sites (humid, mesic and xeric) from contrasting precipitation regimes was evaluated in a common garden trial. Seedlings were submitted to progressive drought by withdrawing irrigation (control vs water deficit). Assuming a genetic base determined by selection pressures, populations from more xeric sites are expected to show higher resistance to drought, e. g., higher resistance to xylem cavitation and safety margin, stronger stomatal control and osmotic adjustment. Vulnerability to cavitation curves were performed, and the percentage loss of conductivity (P12, P50, P88 and slope) was obtained. The water potential at turgor loss point (TLP) and the osmotic potential at full turgor (π100) were calculated from pressure–volume curves. The humid site showed a significantly higher P50 value than the mesic and the xeric sites. Pre-dawn water potential differed between the provenances from xeric and mesic conditions under severe water deficit. Natural selection was inferred from the comparison of differentiation at neutral markers and phenotypic traits (F_ST vs. P_ST), with signals of adaptive variation (P_ST > F_ST) for stomatal density, specific leaf area, TLP, π100 and stomatal conductance. Results suggest a differential adaptive capacity to drought of N. pumilio provenance sites that could be evidencing local adaptation to their home environment.

不同基因型对非生物胁迫的抗性可能是由于遗传效应和/或表型可塑性使它们能够适应各种条件。一种或另一种机制的贡献决定了对物种保护和适应性管理具有影响的不同策略。在这项研究中，Nothofagus pumilio对干旱的生态生理反应在一个共同的花园试验中评估了来自对比降水情况的来源地点（潮湿、中和干旱）。通过取消灌溉（控制与缺水）使幼苗经受渐进式干旱。假设遗传基础由选择压力决定，来自更多干旱位点的种群预计显示出更高的抗旱性，例如更高的木质部空化抗性和安全裕度、更强的气孔控制和渗透调节。对空化曲线进行了易损性分析，并获得了电导率损失百分比（P12、P50、P88 和斜率）。膨胀损失点 (TLP) 的水势和全膨胀 (π100) 的渗透势由压力-体积曲线计算。潮湿场地的 P50 值显着高于中等和干旱场地。在严重缺水的情况下，干旱和中等条件下的种源之间的黎明前水势不同。自然选择是从中性标记的分化和表型性状的比较中推断出来的（F_ST与 P _ST )，具有气孔密度、比叶面积、TLP、π100 和气孔导度的适应性变化信号 (P _ST  > F _ST )。结果表明，N. pumilio原产地对干旱的适应能力不同，这可能证明当地对其家庭环境的适应能力。