Hydroponics has represented an emerging solution for regions with freshwater scarcity. Besides requiring a lower volume of water for production, this cultivation technique allows the use of brackish waters with high salinity levels. Under normal cultivation conditions (i.e., without any environmental control), plants are exposed to other abiotic stresses, such as temperature, which can further enhance the salinity effect. Given the above, three experiments were conducted using a nutrient film technique (NFT) hydroponic system: from April to May (autumn) with endive (Cichorium endivia L., cv. Gigante Barbarella), from May to July (autumn/winter) with lettuce (Lactuca sativa L., cv. Rubinela and cv. Veneranda), and from August to October (winter/spring) with chicory (Cichorium intybus L., cv. Pão de Açúcar and cv. Radiche Todo Ano), in 2021. The trials aimed to evaluate the isolated and/or combined effect of salt and root-zone temperature stresses on yield, water use efficiency, and visual quality of these vegetables. In all experiments, plants were subjected to stresses for 25 days in a randomized block design with a 2 × 4 factorial arrangement: two levels of electrical conductivity of water –ECw (0.30 and 5.50 dS m^–1 for endive and chicory; 0.25 and 6.50 dS m⁻¹ for lettuce) combined with four root-zone temperatures – RZTs (ambient-ARZT, ARZT + 2 °C, ARZT + 4 °C, and ARZT + 6 °C, corresponding to the mean temperatures of 24.72, 26.90, 28.77, and 30.73 °C for endive; 24.20, 26.00, 28.00, and 29.99 °C for lettuce; 27.12, 28.93, 31.01, and 32.86 °C for chicory). The isolated effects of RZT stresses or ECw levels on endive traits were observed, with leaf fresh matter losses of approximately 17 and 44% at higher ARZT + 6 °C (mean of 30.73 °C) and salinity (ECw 5.50 dS m^–1), respectively. Shoot fresh matter losses of around 32 and 52% (Veneranda and Rubinela lettuces, respectively) and 65% (Radiche Todo Ano chicory) occurred only due to salt stress. The interaction affected the shoot fresh matter of Pão de Açúcar chicory, with approximate losses of 80% at higher ARZT + 6 °C (mean of 32.86 °C) and salt stress (ECw 5.50 dS m^–1) than ARZT and ARZT + 2 °C and without salt stress (ECw 0.30 dS m^–1). Despite these reductions, visual quality of plants was not depreciated. Therefore, the present study suggested cultivating leafy vegetables such as lettuce, chicory, and endive using brackish waters, even under high temperatures of nutrient solutions.

水培法是淡水匮乏地区的一种新兴解决方案。除了生产用水量较少外，这种栽培技术还可以使用高盐度的咸水。在正常栽培条件下（即没有任何环境控制），植物暴露于其他非生物胁迫，例如温度，这可以进一步增强盐度效应。鉴于上述情况，使用营养膜技术（NFT）水培系统进行了三个实验：四月至五月（秋季）种植菊苣（菊苣，cv. Gigante Barbarella），五月至七月（秋季/冬季）种植菊苣（Cichorium endivia L.，cv. Gigante Barbarella）。生菜（Lactuca sativa L.、cv. Rubinela 和 cv. Veneranda），以及 8 月至 10 月（冬季/春季）与菊苣 (菊苣 ( Cichorium intybus L.) Pão de Açúcar 和 cv。Radiche Todo Ano），2021 年。试验旨在评估盐和根区温度胁迫对这些蔬菜的产量、水分利用效率和视觉质量的单独和/或综合影响。在所有实验中，植物均采用 2 × 4 阶乘排列的随机区组设计，经受 25 天的胁迫：两个水平的水电导率 –ECw（菊苣和菊苣为 0.30 和 5.50 dS m –1；0.25和^6.50 dS m ⁻¹生菜）与四个根区温度 – RZT（环境 ARZT、ARZT + 2 °C、ARZT + 4 °C 和 ARZT + 6 °C）相结合，对应于平均温度 24.72、26.90、28.77 和 30.73 °C（菊苣）；24.20、26.00、28.00 和 29.99 °C（生菜）；27.12、28.93、31.01 和 32.86 °C（菊苣）。^{观察到 RZT 胁迫或 ECw 水平对菊苣性状的孤立影响，在较高的 ARZT + 6 °C（平均值 30.73 °C）和盐度（ECw 5.50 dS m –1）}下，叶片新鲜物质损失分别约为 17% 和 44%。）， 分别。仅由于盐胁迫，芽新鲜物质损失约 32% 和 52%（Veneranda 和 Rubinela 生菜）和 65%（Radiche Todo Ano 菊苣）。这种相互作用影响了 Pão de Açúcar 菊苣的芽新鲜物质，与 ARZT 和 ARZT + 2 相比，在较高的 ARZT + 6 °C（平均值 32.86 °C）和盐胁迫（ECw 5.50 dS m ^–1）下，损失约 80% °C 且无盐胁迫 (ECw 0.30 dS m ^–1 )。尽管有这些减少，植物的视觉质量并没有降低。因此，本研究建议即使在营养液的高温下，也可以使用微咸水来种植生菜、菊苣和菊苣等叶类蔬菜。