MELATONIN ENHANCED ANTIOXIDANT DEFENSE SYSTEM IN GRAPE CV. "SUMMER ROYAL" TRANSPLANTS UNDER SALT STRESS

An experiment was conducted in Saran house to study the effect of melatonin foliar spraying at 0, 10, 20 mg l(-1) concentrations of Vitis vinifera cv. Summer Royal transplants aged one year on 3 April monthly for 5 times on antioxidant substance and antioxidant enzymes activities under two irrigation water quality (Tap water and Well water). The use of melatonin spraying coefficients with well water irrigation led to significant effects on the traits under study and this was clear that most of them had exceeded their rates in seedlings of melatonin spraying treatments (20 mg l(-1)) irrigated with well water compared to un treated seedlings irrigated with the same type of water, as it caused an increase in polyphenols (21.45, 16.18 mu gKg(-1) DW), flavonoids (8.960, 6.980 mu g Kg(-1) DW) and peroxidase (4.13, 2.78 unit mol(-1)), catalase (1.87, 1.50 unit mol(-1)) enzymes activity in leaves compared to the saplings irrigated with tap water without melatonin. While, the transplants treated with melatonin and irrigated with tap water achieved similar results for the above mentioned values with superiority of means of well water treatment. The gene expression of the genes involved in the formation of polyphenols VvPPO was studied and the results showed that the highest relative amount of gene expression of the gene of total phenolic synthesis (Polyphenol oixdase) VvPPO was the highest possible in the treatment of grape seedlings with tap water and the addition of melatonin at a concentration of 20 mg.