Excessive Pruning Levels in Young Grapevines (Vitis vinifera L. cv. Sultan 7) Cause Water Loss in Seedless Cluster Berries

Abstract

ABSTRACT Late-season dehydration is known as a type of berry shrivel and it is often associated with wine grapes. This study is different from other berry shrivel studies as it focuses on seedless grape cv. Sultan 7 (Vitis vinifera L.) and aims to determine the effects of different pruning levels (90, 150, 180 buds per vine), leaf removal (LR) (25%, 50% per shoot) treatments on vine yield, and the number of harvested clusters. Additionally, we aim to find the effects of treatments on the number of unhealthy clusters with shriveled (S) berries. Although treatments were conducted under the same irrigation practices and determined close leaf water potential values, S berries were not obtained from the vines with 90 buds per vine treatment. Thus, S berries were determined in the lower side of unhealthy clusters together with non-shriveled (NS) berries in treatments of 150 and 180 buds per vine. It was found that the total soluble solids content and titratable acidity of S berries were higher than NS. While high pruning levels per vine enabled to obtain more clusters, the expected yield was negatively affected due to the quantity of the unhealthy cluster. Significant polynomial regression was observed between the number of harvested and unhealthy clusters in 2016 (R2 = 0.69) and 2017 (R2 = 0.76). In this research, it was hypothesized that the water losses in S berries of unhealthy clusters in overloaded vines (150, 180 buds per vine) were caused by obtaining more harvested clusters compared to the 90 buds per vine treatment.