Influence of Exogenous Postharvest Application of Greener Biomolecules on the Quality and Shelf Life of Banana cv. Nendran (AAB) by Regulating Ripening Enzymes and Management of Anthracnose

Climacteric fruits like banana undergo rapid ripening, characterized by a burst in respiration and ethylene production, which negatively impacts their quality and storage life and hastens the spread of postharvest diseases such as anthracnose. The postharvest application of environmentally sustainable biomolecules such as melatonin and salicylic acid could modulate ripening-related enzyme activity and strengthen disease resistance, thereby delaying fruit ripening. Therefore, this study examined the effects of two biomolecules, melatonin (1.0 and 1.5 mM) and salicylic acid (1.0 and 1.5 mM), applied as a 15 min postharvest dip, individually and in combination, on ripening, postharvest quality, shelf life, and disease incidence management in banana cv. Nendran. The postharvest dip of melatonin (1.0 mM) significantly modulated the activity of fruit ripening enzymes like polygalacturonase and pectin methyl esterase by controlling ethylene synthesis and respiration rate. This treatment also maintained the structural integrity of the fruit compared to the conventional treatment under ambient (32 ± 2 °C) and cold storage (14 ± 1 °C) conditions. Interestingly, melatonin reduced anthracnose incidence by maintaining fruit firmness and boosting the antioxidant activity. The melatonin treatment maintained the shelf life of Nendran banana to 12 days in ambient storage and 36 days under cold storage, which are 3 and 5.34 days longer than their respective controls. Though salicylic acid also improved the postharvest quality and shelf life, its performance was comparatively lower than that of melatonin, imparting moderate control over ripening enzymes and effects on disease incidence and shelf life (10.33 and 11 days in ambient storage and 34.67 and 33.67 days in cold storage, respectively, by 1.0 and 1.5 mM salicylic acid dip). These findings suggest that melatonin (1.0 mM) could serve as a promising postharvest treatment for maintaining quality, prolonging shelf life, and managing anthracnose in bananas during storage.