Preharvest melatonin application on enhancing quality and extending shelf life in papaya

Papaya is an important fruit crop, and its cultivation has gaining importance in recent times due to its high economic returns . However,due to its climacteric behaviour and high perishablility, the shelf life of papaya after harvest is very limited. A field experiment was conducted to evaluate the effect of preharvest melatonin applications at different concentrations – 0.5 mM, 1.0 mM, 1.5 mM, and 2.0 mM, along with a control treatment (water spray) on enhancing postharvest quality and prolonging the shelf life of papaya. Among these, the applications of melatonin at 1.5 mM, administed 15 days before harvest, was found to be the most effective in extending the shelf life of papaya by significantly delaying changes in quality parameters. This treatment also resulted in increased antioxidant enzymes activity, improved fruit firmness, delayed ripening enzyme activity, and reduced weight loss. Papaya fruits harvested from trees sprayed with 1.5 mM melatonin exhibited a firmness of 6.37 kg/cm2 under ambient storage and and 6.26 kg/cm2 under cold storage, compared to 5.54 kg/cm2 and 5.33 kg/cm2, respectively, for control fruits. Additionally, total soluble solids (TSS) levels in fruits from the 1.5 mM melatonin treatment were recorded as 12.90 ºB under ambient storage and 13.50 ºB under cold storage, compared to 15.00 ºB and 15.40 ºB, respectively, for control fruits. In conclusion, preharvest melatonin application at 1.5mM effectively delayed postharvest senescence, enhanced fruit quality, and reduced postharvest losses in papaya. This approach could significantly improve market access and industrial adaptability, benefiting both producers and consumers.