The effects of melatonin on the vase life, water relations and endogenous melatonin of cut tuberose cv. Pearl (Polianthes tuberosa L.)

Melatonin plays important and different roles in many aspects of plant growth and development. Recently it has been shown that melatonin has antioxidant properties and plays in processes of germination, maturation, senescence, cytoprotection, resistance to biotic and abiotic stress and etc. However, its role in post-harvest processes and water relations cut flowers has not yet been determined. In this study, the effects of different concentrations of melatonin on five levels (0, 50, 100, 250 and 500 µM) and three times (2, 4 and 6 hours) on the cut tuberose cv. Pearl were investigated as pulse treatments. cut flowers were then transferred to distilled water and evaluated daily for vase life and water relations. However, pulse treatments for 4 h with 250 µM melatonin solutions extended vase life and suppressed a reduction in fresh weight during the post-harvest period. The amounts of water uptake and water loss by the cut flowers decreased upon melatonin treatment. The results showed that melatonin treatment resulted in prolonged vase life, increasing the number of opened florets in the inflorescence, reducing water loss and maintaining the water balance in cut tuberose. Treatment of 250 µM melatonin resulted in a 1.5-fold increase in vase life of cut tuberose compared to control treatment. The highest water uptake and water loss were observed in control treatment and the lowest water uptake and water loss were observed in treatment with 500 µM melatonin. As the melatonin concentration increased, endogenous melatonin levels increased. Melatonin application caused a positive change in chlorophyll and carotenoid levels. The role of melatonin at high concentrations (500 µM) may be similar to the abscisic acid in stomata closure and reduced transpiration, or at concentrations of 100 and 250 µM melatonin, possibly maintaining cells membrane integrity, may cause turgidity of cells