Foliar application of sodium nitroprusside alters the physicochemical properties, antioxidant capacities, and enzymatic activities of strawberry cv. Camarosa

Strawberry (Fragaria × ananassa) is a horticultural crop known for its sensitivity to mechanical damage and susceptibility to postharvest decay. In recent years, various strategies have been implemented to enhance both the yield and quality of strawberries, among which the application of nitric oxide-producing compounds has garnered special attention. The present study aimed to investigate the effects of varying concentrations of sodium nitroprusside (SNP), specifically 0, 200, 400, and 600 μM, on strawberries (cv. Camarosa) cultivated in a soilless culture system. It was attempted to identify optimal treatment concentrations that would improve the quality and yield of the strawberries. The analysis of variance revealed significant differences (p ≤ 0.01) in all morphological and phytochemical properties, as well as antioxidant and enzymatic activities, between the treated samples and the control group. Notably, the highest concentrations of total phenolics, phenylalanine ammonia-lyase (PAL) enzyme activity, guaiacol peroxidase enzyme activity, and potassium content in the fruit were recorded at the 400 μM SNP treatment. Specifically, these values were 6.67 mg GAE 100 g⁻¹ FW, 57.42 nmol g⁻¹ FW min⁻¹, 0.183 μmol H₂O₂ min^-1 100 ml^-1 extract, and 5.9% DW, respectively. Furthermore, the 200 μM SNP treatment yielded the highest ascorbic acid content (0.587 mg AA 100 g^-1 FW) and the lowest 50% inhibitory concentration for free radicals at 44.18 μl. In contrast, the 600 μM treatment resulted in the highest total flavonoid content (0.529 mg QE 100 g⁻¹ FW). In conclusion, the findings indicated that SNP treatment can effectively enhance the yield and improve the quality and marketability of the strawberry fruit.