Selenium and fertigation timing improve strawberry performance and biofortification under salinity stress

Salinity is a significant constraint for strawberry production worldwide, as it reduces plant growth, nutrient uptake, and antioxidant balance, ultimately limiting yield and fruit quality. Here, we investigated the influence of selenium supplementation and the fertigation time application on strawberry plant performance under saline conditions. 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 (0 and 40 mM NaCl). Selenium was supplied as sodium selenate (0 or 1 mg L ^− 1 ), and nutrient solutions were applied at four timings: morning, afternoon, both, or a mixed morning/afternoon ratio. Plant growth, biomass allocation, antioxidant activity, ion accumulation, and fruit selenium concentration were assessed to evaluate stress mitigation. Under salinity, the morning full-concentration nutrient solution with selenium minimized yield reduction (24%) and promoted the highest root and shoot dry weights. This treatment also enhanced antioxidant defenses, including free radical inhibition (80%), anthocyanin content, and superoxide dismutase activity, while improving K and Ca accumulation in shoots. Selenium supplementation increased fruit selenium concentrations to 2.2–3.1 mg kg ^− 1 dry weight. Comparatively, treatments applied in the afternoon or without selenium were less effective at mitigating salinity-induced stress. These results indicate that combining selenium application with morning nutrient delivery effectively enhances strawberry tolerance to salinity by improving antioxidant systems, nutrient absorption, and overall plant performance. The findings provide a practical framework for managing salinity stress in controlled environmental systems. Future research should assess whether these timing effects occur in other cultivars and production systems and physiologically determine selenium doses that optimize biofortification without compromising plant performance. Field studies will be necessary to decide on the optimal selenium doses that maximize fruit quality and biofortification without compromising plant performance.