Protective structures and manganese amendments effects on antioxidant activity in pepper fruit

• High temperatures modify antioxidant activity in peppers at different ripening stages.
• Cultivars ability to cope with temperature damages correlated with their antioxidant activity.
• Manganese modifies pepper antioxidant activity, with different response for each cultivar.
• Pepper fruits nutritional quality augment with manganese addition at selected ripening stages.

Sweet pepper (Capsicum annuum L.) is an excellent source of bioactive nutrients. Manganese is a crucial micro-element for plant nutrition, has a role in photosynthesis, and is a cofactor in antioxidant enzymes. Pepper fruit grown under a protective environment are nevertheless exposed to high temperatures during the summer that cause oxidation-related heat damage to the pericarp beneath the fruit skin. We demonstrate that high temperatures significantly modify total antioxidant activity in peppers at different ripening stages. Pepper cultivars differ in their antioxidant activity, which was correlated with their ability to cope with high temperature damages. Manganese applied to pepper plants modifies antioxidant activity, but different cultivars responded differently to the manganese application. In summary, pepper fruit grown under temperature stress will possess higher antioxidant activity than those grown at lower temperatures and will therefore be of higher nutritional value for human consumption. Agronomic practices such as growing conditions or manganese supply may alter, in a cultivar-specific manner, the antioxidant activity and the nutritional values of the crop.

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