Interactive effects of hydroponic systems, nitrogen concentration, and genotype on growth, yield, and nutritional quality of spinach beet

Hydroponic cultivation offers an efficient approach for intensive leafy vegetable production under protected environments. However, crop performance depends on interactions among cultivation system, nitrogen (N) management, and genotype. This study evaluated the effects of two hydroponic systems nutrient film technique and growing bag three N concentrations (N1 = 6, N2 = 8, and N3 = 10 mmol L−1), and six spinach beet (Beta vulgaris var. bengalensis) genotypes on growth, yield, and nutritional quality under greenhouse conditions. The experiment was conducted during the rabi seasons of 2021–2022 and 2022–2023 using a 2 × 3 × 6 factorial completely randomized design with three replications. Data were analyzed using linear mixed-effects models with year as a random effect, complemented by correlation and multivariate analyses. The nutrient film technique system significantly enhanced vegetative growth, green leaf yield, and nutritional quality compared with the growing bag system. Among the N treatments, N2 (8 mmol L−1) produced the best growth and yield responses, while genotype G3 consistently showed superior overall performance, followed by G1. Overall, integrating the nutrient film technique system with N2 and superior genotypes provides an effective strategy for improving spinach beet productivity and nutritional quality under protected cultivation.