Foliar Salicylic Acid Application Modulates Yield and Physicochemical Characteristics of Hydroponic Cherry Tomatoes Under Salt Stress

Water limitations in the Brazilian semi-arid region require saline water utilization. Hydroponic cultivation combined with salicylic acid (SA) elicitation represents a strategy to manage salt stress in cherry tomatoes. This study evaluated the effects of foliar SA application on the production and quality of cherry tomatoes under saline nutrient solutions. An NFT hydroponic greenhouse experiment at UFCG, Pombal, Brazil, evaluated five nutrient solution salinities (ECns: 2.1, 2.6, 3.1, 3.6, and 4.1 dS m−1) and five SA concentrations (0, 0.8, 1.6, 2.4, and 3.2 mM) in a split-plot design with three replications. SA concentrations from 1.3 to 3.2 mM enhanced fruit diameter, fruit number, average weight, and yield under baseline salinity (2.1 dS m−1). At 3.2 mM, SA functioned as an optimal ratio regulating nutritional quality, increasing titratable acidity and ascorbic acid under 2.1 and 2.6 dS m−1, respectively. Conversely, high salinity (4.1 dS m−1) established a promotion pattern on soluble solids, maturity index, and flavonoids, while reducing yield components by up to 58.3%, demonstrating explicit operational limitations of SA under severe stress. These baseline findings validate the applicability of SA within specific salinity thresholds, establishing a foundational framework for subsequent physiological profiling, fruit quality characterization at harvest, and commercial greenhouse upscale validation.