Biochemical Changes induced by Hydrogen Cyanamide (Dormex) Foliar Application in the Buds of ‘Askari’ Grape

Abstract

Abstract Short growing season is one of the main obstacles to the commercial production of grapes in regions experiencing cold/semi-cold climates. This is known to impact the quality and quantity of production. Consequently, this study was conducted to evaluate the effects of foliar application of hydrogen cyanamide (Dormex) solution (0, 1%) as a rest-break agent and its physiological and biochemical mechanisms, on 10-year-old Askari grape (Vitis vinifera 'Askari') trees, in a completely randomized block design in a factorial combination with three replications. The results showed that catalase activity was lower in the samples treated with hydrogen cyanamide solution (1%) compared to the untreated buds during the second, third, and fourth sampling dates, and hydrogen peroxide accumulated in the buds during the same period. Putrescine concentration was increased more than 6 folds in hydrogen cyanamide treated (1%) samples during the bud dormancy release period compared to the first sampling date, while spermidine and spermine concentration showed a significant decrease (about 90% and 80% respectively). Hydrogen cyanamide treatment also resulted in increased total nitrogen concentration in buds due to a rise in amino acids' concentration (proline, glutamine, arginine, ornithine, and citrulline). In conclusion, the current findings showed that the hydrogen cyanamide application enhanced bud break by 7.78% and 6.67%, 20 and 30 days after hydrogen cyanamide solution spray application, respectively.