Pre‐harvest application of sodium nitroprusside enhances storage root quality in red beet cultivated under normal and drought conditions

BACKGROUND The role of nitric oxide (NO) in plant stress tolerance, as well as in increasing post‐harvest quality, has been extensively demonstrated in several fruits and vegetable crops; however, the effects of its pre‐harvest application on post‐harvest quality are still poorly documented. Therefore, the pre‐harvest application of NO in red beet (Beta vulgaris subsp. vulgaris) plants cultivated under well‐watered and drought conditions was evaluated to assess whether it improves the post‐harvest quality of their storage roots. Red beet plants cultivated under well‐watered (80% of water holding capacity) or drought condition (15% of water holding capacity) were sprayed weekly with water (control) or 100 μmol L−1 sodium nitroprusside (SNP), an NO donor. Sixty‐six days after sowing, red beet roots were harvested, and root yield, total sugar yield, reducing sugars, non‐reducing sugars, proteins, lipids, root ashes, root moisture, soluble solids, titratable acidity, pH, vitamin C, total phenolics, total betalains, betacyanins, betaxanthins and antioxidant capacity were determined. RESULTS While drought led to a reduction in root yield, sugars, lipids and titratable acidity, it increased phenolic compounds, betalains and the antioxidant capacity of beets. SNP reversed the negative effects of drought on sugar, lipid and organic acid contents and increased antioxidant capacity independent of stress. CONCLUSION Pre‐harvest SNP treatment reversed drought‐induced yield reductions in beets, while boosting bioactive compounds and antioxidant capacity. It also enhanced vitamin C content independently, indicating its dual role in stress mitigation and beet quality improvement. Future research should explore other crops and stress conditions. © 2024 Society of Chemical Industry.