Optimizing nitrogen and sulfur supplementation for enhanced growth and biochemical composition in Solanum lycopersicum under hydroponic conditions

Solanum lycopersicum (tomato) is a globally significant crop valued for its nutritional and economic importance. This study investigated the effects of nitrogen (N) and sulfur (S) supplementation on tomato growth, biochemical profiles, and stress responses in a hydroponic system. Five treatments were tested: T1 (0% N, 0% S), T2 (50% N, 50% S), T3 (100% N, 100% S, control), T4 (250% N, 250% S), and T5 (500% N, 500% S). Results suggest that T3 (100% N, 100% S) supported optimal growth (plant height: 35.3 cm, leaf number: 33.3, root weight: 1.48 g), while T1 exhibited severe deficiency symptoms and T5 showed signs of nutrient toxicity. Biochemical analyses revealed strong positive correlations between N/S availability and chlorophyll (r = 0.92, p < 0.01), carotenoids (r = 0.89, p < 0.01), and protein content (r = 0.95, p < 0.01). T5 displayed elevated antioxidant enzyme activities (CAT: 0.42 μmol/min/mg protein; APX: 2.40 μmol/min/mg protein) and increased cell death (40.0%), indicating metabolic stress. These findings suggest that the 100% N/S treatment was optimal for tomato growth and biochemical composition in hydroponic systems, while excessive nutrients induce stress. This study highlights the importance of precise nutrient management for sustainable hydroponic tomato production. Limitations include the use of a single cultivar, a small sample size (n = 3), and a controlled hydroponic environment, which may not fully represent field conditions.