Effect of z inc oxide nanoparticles on capsaicinoids, antioxidant enzymes, and zinc biofortification in habanero pepper

Nanoparticles are promising agriculture tools because they can influence crop productivity, stress responses and nutritional quality. This study evaluated the effect of foliar application of zinc oxide nanoparticles (ZnO-NPs) on bioactive compounds, capsaicinoids, antioxidant enzyme activity, and Zn accumulation in greenhouse-grown Capsicum chinense Jacq. cv. Orange during the May-November 2024 growing period. Plants received 0, 20, 30, and 40 mg.L-1 ZnO-NPs in a completely randomized design. The 40 mg.L-1 treatment produced the highest antioxidant capacity, total flavonoids, total carotenoids, capsaicin, dihydrocapsaicin, catalase and peroxidase activities, and Zn accumulation, whereas the 20 mg.L-1 maximized total phenols. These results suggest that ZnO-NPs act as metabolic elicitors, stimulating antioxidant defense mechanisms and secondary metabolism while enhancing Zn biofortification in habanero pepper fruits. Foliar ZnO-NPs therefore represent a promising strategy to improve the nutritional and functional quality of habanero pepper.