Influence of a Preharvest Melatonin Application on Postharvest Chilling Injury in Basil (Ocimum basilicum L.)

Postharvest chilling injury is a physiological disorder detrimental to produce quality and shelf-life. Basil (Ocimum basilicum L.) is susceptible to postharvest chilling injury at temperatures below 12 °C, manifesting as leaf lesions and discoloration. Melatonin, a growth regulator, has reduced postharvest chilling injury severity in produce, but its effect on basil is unknown. Here, we evaluated the impact of an exogenous preharvest melatonin application at 400 μM on basil leaves stored at 3.5 °C for 12 days. Visual parameters, including objective color descriptors, chilling injury index, and damaged surface area, as well as biochemical (total soluble solids, malondialdehyde, and total polyphenol content) and physiological (electrolyte leakage and fresh weight loss) markers for cold stress, were assessed. Melatonin-treated leaves showed reduced symptoms (15–22%) relative to the untreated control after cold storage. The biochemical and physiological parameters displayed subtle changes between treatments after storage. However, melatonin induced alterations before storage (70–90%), suggesting it acted as a stressor.