Interactive effects of selenium and fertigation regimes on strawberry performance and biofortification under salinity...

Salinity is a significant constraint for strawberry production worldwide. This study investigated the effects of selenium (Se) supplementation and different fertigation regimes on strawberry plant performance under saline conditions. The experiment was conducted as a three‑factor factorial arrangement in a completely randomized design with four replicates. Rooted daughter plants of the cv. 'Paros' were grown in 3-L pots with a perlite-coir pith mixture and exposed to two salinity levels (control or without NaCl and 40 mM NaCl). Se was supplied as sodium selenate (0 or 1 mg L^- 1). The third factor was fertigation regime at four levels: morning Hoagland (M-H, 8:00 AM, daily), afternoon Hoagland (A-H, 8:00 PM, daily), both morning and afternoon Hoagland (MA-H, 8:00 AM and 8:00 PM, every other day) and mixed morning/afternoon Hoagland at a 1:2 ratio (MA-1/2H, 8:00 AM and 8:00 PM, daily). Salinity and Se were applied via the nutrient solution. Under salinity, the M-H treatment with Se was associated with reduced yield loss (24%, P < 0.05) and higher root and shoot dry weights compared to other fertigation regimes. This treatment also showed associations with enhanced antioxidant responses, including free radical inhibition (80%), higher anthocyanin content, and increased superoxide dismutase activity, along with improved K and Ca accumulation in shoots. Se supplementation increased fruit Se concentrations to 2.2-3.1 mg kg^- 1 dry weight. These results indicate that combining Se application with M-H delivery is a promising strategy to mitigate salinity-induced stress in controlled environment systems. Future research is required to evaluate these regime-dependent responses in other cultivars and to optimize Se doses for biofortification while maintaining peak plant performance.