This research aims to evaluate the impact of nitrogen deprivation and water stress on gas exchange and chlorophyll fluorescence in young plants of five cultivars of Arabic coffee. A factorial experiment 5 (cultivars) × 3 (treatments: control without stress, water stress of −1.5 MPa and stress of N – 0.0 mmol L⁻¹ N) was carried out in a complete randomized block design with three replicates. Before being submitted to the treatments, the plants were grown in a greenhouse for 240 days, and then transferred to a growth chamber under controlled conditions. Subsequently, after the experimental period of 96 h we measured photosynthetic rate (A), stomatal conductance to water vapor (g_s), transpiratory rate (E), internal and external carbon ratio (Ci/Ca), water use efficiency (A/E), electron transport rate (ETR), actual quantum yield of PS II electron transport (φFSII), and maximum photochemical efficiency of PS II (Fv/Fm). Water stress reduced A, g_s, E, A/E, ETR, φFSII, and Fv/Fm. The nitrogen deficiency reduced ETR, φFSII, and Fv/Fm. Under short-term water stress Catuaí Vermelho maintain the A values due to better stomatal control, reduced water lost by transpiration (E) and better water use efficiency A/E, while Mundo Novo and Acauã show lower damage to Fv/Fm. Short-term nitrogen stress has low impact on A of young plants of Coffea arabica cultivars with adequate N-nutrition.

这项研究旨在评估氮缺乏和水分胁迫对五个阿拉伯咖啡品种的年轻植物中气体交换和叶绿素荧光的影响。在一个完整的随机区组设计中进行了5次（品种）×3（处理：无压力的对照，−1.5 MPa的水分胁迫和N – 0.0 mmol L ^-1 N的胁迫）的三项重复实验。在进行处理之前，将植物在温室中生长240天，然后在受控条件下转移至生长室。随后，在96小时的实验期后，我们测量了光合速率（A），气孔对水蒸气的电导率（g _s），蒸腾速率（E），内部和外部碳比（Ci / Ca），水利用效率（A / E），电子传输速率（ETR），PS II电子传输的实际量子产率（φFSII）和PS II的最大光化学效率（Fv / Fm）。水分胁迫降低了A，g _s，E，A / E，ETR，φFSII和Fv / Fm。氮缺乏会降低ETR，φFSII和Fv / Fm。在短期水分胁迫下，由于更好的气孔控制，蒸腾作用减少了水分流失，Catua Vermelho保持了A值（E）和更好的用水效率A / E，而Mundo Novo和Acauã对Fv / Fm的损害较小。短期氮素胁迫对充足营养的阿拉比卡咖啡幼树的A影响较小。