Increasing atmospheric CO2 concentrations ([CO2]) are unequivocal, widespread, and responsible for increased mean global temperatures and altered precipitation patterns. In this context, among the topics that need to be better understood are the changes in the water-related processes and gas exchange properties of plants grown under these conditions. Notably, the effects of climate change on coffee (Coffea spp.) production are particularly concerning given the importance of this commodity. Especially, it has been reported that coffee trees exhibit better photosynthetic efficiency when grown at higher [CO2] levels. In order to elucidate the mechanisms involved with this response, the seasonality of water-related processes, gas exchange, and carbohydrate metabolism were investigated using C. arabica var. Red Catuaí grown at ambient and high [CO2] under field conditions, at a free-air CO2 enrichment (FACE) facility for coffee, in Brazil. The trees were evaluated fortnightly, from November to February (hot and rainy—summer) and from June to September (cold and dry—winter). It was found that C. arabica trees grown under high [CO2] conditions exhibited increased photosynthetic rates (averaging 121% higher in summer and 45% higher in winter) in both seasons, without displaying any significant changes in the seasonal photosynthesis pattern. Additionally, there was a tendency for the coffee trees grown at high [CO2] to exhibit increased levels of soluble carbohydrates, organic acids, and amino acids in the leaves. Our findings suggest that coffee trees adapt to increased [CO2] through increased photosynthetic rates, enhanced stomatal conductance regulation, and augmented carbohydrate and organic acid synthesis. It is plausible that these features could help mitigate the effects caused by climate change.

中文翻译：

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高大气 CO2 浓度对田间条件下咖啡树与水有关的过程、气体交换和碳水化合物代谢的季节性影响

大气 CO2 浓度 ([CO2]) 的增加是明确的、普遍的，并且是导致全球平均温度升高和降水模式改变的原因。在这种情况下，需要更好地理解的主题包括在这些条件下生长的植物与水相关的过程和气体交换特性的变化。值得注意的是，鉴于这种商品的重要性，气候变化对咖啡（Coffea spp.）生产的影响尤其令人担忧。特别是，据报道，咖啡树在较高 [CO2] 水平下生长时表现出更好的光合效率。为了阐明与这种反应有关的机制，使用 C. arabica var. 研究了与水相关的过程、气体交换和碳水化合物代谢的季节性。Red Catuaí 在野外条件下在环境和高 [CO2] 条件下生长，在巴西的一个用于咖啡的自由空气二氧化碳富集 (FACE) 设施中。每两周对树木进行一次评估，从 11 月到 2 月（炎热多雨 - 夏季）和从 6 月到 9 月（寒冷干燥 - 冬季）。发现在高 [CO2] 条件下生长的 C. arabica 树在两个季节都表现出光合速率增加（夏季平均高 121%，冬季平均高 45%），而季节性光合作用模式没有任何显着变化。此外，在高 [CO2] 条件下生长的咖啡树倾向于表现出叶子中可溶性碳水化合物、有机酸和氨基酸的含量增加。我们的研究结果表明，咖啡树通过增加光合速率来适应增加的 [CO2]，增强气孔导度调节，增强碳水化合物和有机酸合成。这些特征可能有助于减轻气候变化造成的影响。