Nutrient biofortification in leafy vegetables is a promising strategy to enhance dietary health benefits, improve crop nutritional quality, and promote sustainable agricultural practices. Advanced plant cultivation techniques, such as hydroponic production and targeted micronutrient fertilization, provide a controlled environment for optimizing nutrient uptake and secondary metabolite synthesis. Selenium (Se), an essential micronutrient, has been shown to influence plant metabolism, particularly the synthesis of bioactive compounds such as carotenoids and glucosinolates. However, its role in modulating these phytochemicals in hydroponically grown Nasturtium officinale (watercress) and Barbarea verna (upland cress) remains underexplored. This ongoing study investigates the effects of selenium fertilization at varying concentrations (0, 1.0, 2.0, and 4.0 mg Se·L⁻¹) on carotenoid and glucosinolate accumulation in two cress varieties cultivated under controlled hydroponic conditions. The hydroponic system provides a consistent environment for plant growth, allowing precise manipulation of nutrient levels, pH, temperature, and light intensity. Selenium treatments follow a randomized complete block design to ensure replication and statistical rigor. Growth parameters, biomass accumulation, and biochemical analyses of carotenoid and glucosinolate levels are being monitored to determine the interactions between selenium uptake and secondary metabolite biosynthesis. Carotenoid content in plant tissues will be quantified using high-performance liquid chromatography (HPLC), while glucosinolate concentrations will be determined through chromatographic and spectrophotometric methods, ensuring precise assessment of bioactive compound accumulation. Preliminary observations suggest that selenium supplementation may modulate plant physiological responses, potentially enhancing carotenoid and glucosinolate synthesis. Differences in metabolite accumulation between the two cress varieties indicate potential genotype-specific responses to selenium fertilization. Understanding these interactions will contribute to optimizing hydroponic production systems, improving the nutritional and functional quality of leafy greens, and informing sustainable agricultural practices. Findings from this study could advance nutrient-fortification strategies, enhance functional food development, and address micronutrient deficiencies, thereby supporting both horticultural innovation and public health. Keywords: Selenium fertilization, Beta-carotene, Hydroponic, Watercress varieties, Agricultural sustainability, Crop yields, Environmental impact, Spectrophotometric analysis,
