Impact of drought under enriched CO2 atmosphere on ecophysiological and leaf metabolic response of the sub-mediterranean Q. pyrenaica oak was studied. Seedlings growing in climate chamber were submitted to moderate drought (WS) and well-watered (WW) under ambient ([CO2]amb =400 ppm) or CO2 enriched atmosphere ([CO2]enr =800 ppm). The moderate drought endured by seedlings brought about a decrease in leaf gas exchange. However, net photosynthesis (Anet) was highly stimulated for plants at [CO2]enr. There was a decrease of the stomatal conductance to water vapour (gwv) in response to drought, and a subtle trend to be lower under [CO2]enr. The consequence of these changes was an important increase in the intrinsic leaf water use efficiency (WUEi). The electron transport rate (ETR) was almost a 20 percent higher in plants at [CO2]enr regardless drought endured by seedlings. The ETR/Anet was lower under [CO2]enr, pointing to a high capacity to maintain sinks for the uptake of extra carbon in the atmosphere. Impact of drought on the leaf metabolome, as a whole, was more evident than that from [CO2] enrichment of the atmosphere. Changes in pool of non-structural carbohydrates were observed mainly as a consequence of water deficit including increases of fructose, glucose, and proto-quercitol. Most of the metabolites affected by drought back up to levels of non-stressed seedlings after rewetting (recovery phase). It can be concluded that carbon uptake was stimulated by [CO2]enr, even under the stomatal closure that accompanied moderate drought. In the last, there was a positive effect in intrinsic water use efficiency (WUEi), which was much more improved under [CO2]enr. Leaf metabolome was little responsible and some few metabolites changed mainly in response to drought, with little differences between [CO2] growth conditions.

中文翻译：

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富集CO2大气下栎树幼苗对中度干旱叶片生态生理和代谢反应

研究了富含 CO2 大气下干旱对亚地中海 Q. pyrenaica Oak 生态生理和叶片代谢反应的影响。在气候室中生长的幼苗在环境（[CO2]amb = 400 ppm）或富含 CO2 的大气（[CO2]enr = 800 ppm）下经受中等干旱 (WS) 和充分浇水 (WW)。幼苗忍受的中度干旱导致叶片气体交换减少。然而，植物的净光合作用 (Anet) 在 [CO2]enr 下受到高度刺激。响应干旱，气孔导度对水蒸气 (gwv) 有所降低，并且在 [CO2]enr 下有降低的微妙趋势。这些变化的结果是叶片内在水分利用效率 (WUEi) 的重要提高。无论幼苗是否经受干旱，在 [CO2]enr 下，植物的电子传递率 (ETR) 几乎高出 20%。ETR/Anet 在 [CO2]enr 下较低，表明其保持吸收大气中额外碳的汇的能力很强。总的来说，干旱对叶片代谢组的影响比大气中的 [CO2] 富集更为明显。观察到的非结构性碳水化合物池的变化主要是由于水分不足，包括果糖、葡萄糖和原槲皮醇的增加。大多数受干旱影响的代谢物在再润湿（恢复阶段）后恢复到未受胁迫的幼苗水平。可以得出结论，即使在伴随中度干旱的气孔关闭下，[CO2]enr 也刺激了碳吸收。在最后，对内在用水效率 (WUEi) 有积极影响，在 [CO2]enr 下改善得更多。叶代谢组几乎没有责任，一些代谢物主要响应干旱而发生变化，[CO2] 生长条件之间的差异很小。