Manzi Olivier Jean Leonce, Bellifa Maxime, Ziegler Camille, Mihle Louis, Levionnois Sébastien, Burban Benoit, Leroy Céline, Coste Sabrina, Stahl Clément
UMR EcoFoG, CNRS, CIRAD, INRAE, AgroParisTech, Université des Antilles, Université de Guyane, 97310 Kourou, France.
Integrated Polytechnic Regional College-Kitabi, Rwanda Polytechnic, PO Box 330, Huye, Rwanda.
Tree Physiol. 2022 Jan 5;42(1):114-129. doi: 10.1093/treephys/tpab092.
Climate models predict an increase in the severity and the frequency of droughts. Tropical forests are among the ecosystems that could be highly impacted by these droughts. Here, we explore how hydraulic and photochemical processes respond to drought stress and re-watering. We conducted a pot experiment on saplings of five tree species. Before the onset of drought, we measured a set of hydraulic traits, including minimum leaf conductance, leaf embolism resistance and turgor loss point. During drought stress, we monitored traits linked to leaf hydraulic functioning (leaf water potential (ψmd) and stomatal conductance (gs)) and traits linked to leaf photochemical functioning (maximum quantum yield of photosystem II (Fv/Fm) and maximum electron transport rate (ETRmax)) at different wilting stages. After re-watering, the same traits were measured after 3, 7 and 14 days. Hydraulic trait values decreased faster than photochemical trait values. After re-watering, the values of the four traits recovered at different rates. Fv/Fm recovered very fast close to their initial values only 3 days after re-watering. This was followed by ETRmax, Ψmd and gs. Finally, we show that species with large stomatal and leaf safety margin and low πtlp are not strongly impacted by drought, whereas they have a low recovery on photochemical efficiency. These results demonstrate that πtlp, stomatal and leaf safety margin are a good indicators of plant responses to drought stress and also to recovery for photochemical efficiency.
气候模型预测干旱的严重程度和频率将会增加。热带森林是可能受到这些干旱严重影响的生态系统之一。在此，我们探究水力和光化学过程如何响应干旱胁迫及复水情况。我们对五个树种的树苗进行了盆栽实验。在干旱开始之前，我们测量了一系列水力性状，包括最小叶片导度、叶片抗栓塞能力和膨压丧失点。在干旱胁迫期间，我们在不同萎蔫阶段监测了与叶片水力功能相关的性状（叶片水势（ψmd）和气孔导度（gs））以及与叶片光化学功能相关的性状（光系统II的最大量子产率（Fv/Fm）和最大电子传递速率（ETRmax））。复水后，在3天、7天和14天后测量相同的性状。水力性状值比光化学性状值下降得更快。复水后，这四个性状的值以不同速率恢复。Fv/Fm在复水仅3天后就很快恢复到接近其初始值。其次是ETRmax、Ψmd和gs。最后，我们表明具有大的气孔和叶片安全边际以及低膨压丧失点的物种受干旱影响不大，而它们的光化学效率恢复较低。这些结果表明，膨压丧失点、气孔和叶片安全边际是植物对干旱胁迫以及光化学效率恢复响应的良好指标。
