Sodium nitroprusside as a signal molecule for up-regulating membrane characteristics, antioxidant defense system to improve flax productivity under water stress

Water stress is a critical environmental adversity that significantly impacts the growth, development, and yield of flax plants. In this study, flax seeds were cultivated under different water irrigation requirements (WIR) (100%, 75%, and 50%) to investigate the effects of exogenously supplied nitric oxide (NO) donor sodium nitroprusside (SNP) as foliar treatments at concentrations of 0.0 ​mmol/L, 0.5 ​mmol/L, 1.0 ​mmol/L, and 2.0 ​mmol/L. Drought stress led to a significant decrease in plant growth, photosynthetic pigments, yield components such as oil and total carbohydrate percentage. It also resulted in an increase in leaf H₂O₂ production, lipid peroxidation levels and activities of enzymatic antioxidants including polyphenol oxidase, superoxide dismutase, and nitrate reductase enzymes. However, foliar application of SNP improved photosynthetic pigments and antioxidant defense system which mitigated the negative impact of water stress on growth and yield productivity by reducing oxidative damage caused by reactive oxygen species accumulation. The use of SNP also decreased H₂O₂ accumulation levels, lipid peroxidation levels, and improved membrane stability. SNP treatment at concentration of 2 ​mmol/L showed superior results compared to other concentrations with extremely significant increases observed in yield characteristics such as oil content, total carbohydrate percentages, and unsaturated fatty acids to saturated fatty acids ratio.