Effects of Girdling Treatments at Different Periods and Thicknesses on Grape Quality in Yalova Çekirdeksizi (V. vinifera L.) Grape Variety

This research was carried out in 2022 and 2023 to determine the effects of different thickness and single–double girdling treatments on grape quality in different phenological periods of Yalova Seedless grape variety grown in the 'Table Grape Varieties Application and Research Vineyard' located in the ‘ÇOMÜ Dardanos Campus, Faculty of Agriculture, Plant Production Research and Application Unit’. Within the scope of the research, a total of 9 treatments, including the control, were carried out in two different phenological periods pre–bloom and post–berry set, followed by two different thicknesses of single repeated girdling treatments, and double repeated girdling treatments during the veraison period. As a result; the decrease in yield in the 5 mm girdling treatments may be due to the removal of a thicker bark+phloem layer, resulting in a later closure of the wound tissues compared to the 3 mm girdling treatments, and thus a decrease in assimilate products to the main root and old parts. Therefore, it was concluded that although 5 mm girdling treatments continue to give positive results in terms of grape quality in many parameters, it is not appropriate to repeat them two years in a row in terms of average yield.