Effects of sodium nitroprusside (SNP) application on oxidative damage in pepper (Capsicum annuum L.) plants under heat stress

Heat stress is a major abiotic factor limiting plant growth and productivity. Sodium nitroprusside (SNP), a nitric oxide (NO) donor, plays an important role in regulating plant responses to abiotic stress. This study investigated the effects of SNP application on growth parameters, total chlorophyll content, and oxidative stress indicators in Capsicum annuum L. seedlings grown under high temperature conditions. Plants were grown at 25 °C (control) and 38 °C (heat stress) and treated with 50 and 100 µM SNP. The results showed that heat stress reduced growth parameters and total chlorophyll content, while increasing lipid peroxidation (MDA) and hydrogen peroxide (H₂O₂) accumulation. Heat stress enhanced catalase (CAT) activity. Under heat stress, 50 µM SNP alleviated oxidative damage by reducing MDA and H₂O₂ levels, whereas 100 µM SNP increased these parameters. In contrast, SNP application suppressed CAT activity in a dose-dependent manner. These findings indicate that SNP induces dose-dependent physiological and biochemical responses in Capsicum annuum L. seedlings under heat stress and that appropriate SNP doses may contribute to mitigating heat stress–induced damage. The results may also support the development of dose based stress management strategies for sustainable crop production under high temperature conditions.