Petal browning is the primary limiting factor compromising the postharvest quality of narcissus (Narcissus tazetta L.) cut flowers. This study investigated the effects of melatonin (0.25 and 0.50 mM, each in 2% sucrose), compared with a control (distilled water) and sucrose alone (2%), on color stability, browning development, water status, membrane integrity, and browning-related enzyme activities of cut narcissus flowers during vase life. Melatonin treatment reduced the total color change ($\Delta E$) and delayed the progression of petal browning throughout the vase period. The lowest polyphenol oxidase (PPO) and peroxidase (POD) activities were observed in flowers treated with 0.25 mM mel... More >