Neck bending and petal wilting are major postharvest issues that reduce the quality and vase life of Gerbera jamesonii cut flowers. This study evaluated the effects of melatonin (MLT) applied in vase solutions at 0, 100, 200, 300, and 400 μM over 3, 6, and 9 days on neck bending, vase life, and key biochemical parameters in the ‘Pink Elegance’ cultivar. Neck bending increased progressively during storage, but MLT treatments, especially at 300 and 400 μM, significantly reduced bending and extended vase life. Treatment with 300 μM MLT enhanced water uptake, decreased electrolyte leakage and ROS (superoxide and H₂O₂), and delayed senescence, increasing vase life by 4 days (≈50% longer than controls). MLT also preserved phenolic and flavonoid contents, promoted lignin biosynthesis via upregulation of PAL, CCR, and CAD, and elevated antioxidant enzyme activities (CAT, POD, SOD). Additionally, endogenous levels of salicylic acid (SA) and nitric oxide (NO) were increased, supporting stress tolerance and senescence regulation. Overall, melatonin at 300 μM effectively improves postharvest quality and longevity of Gerbera by reducing neck bending through combined effects on signaling pathways, antioxidant defenses, and stem structural reinforcement.
