Effect of rootstock on grafted grapevine quality

As the home of numerous grape genotypes, Turkey is one of the major centers of viniculture genetic material in the world. 'Merzifon Karasi' (Vitis vinifera L.) is one of the most valuable red wine grape cultivars in Turkey. However, despite the variety's relative age, 'Merzifon Karasi' has yet to be tested on different rootstocks. Therefore, this study was conducted to determine the effects of different rootstocks on the growth characteristics of 'Merzifon Karasi' scion. Growth parameters (shoot length (cm), shoot diameter (mm), internode length (cm), total and unit leaf area (cm2), root length (cm), root scale (0-4) and root number) were calculated and carbohydrate content (%) of the grafted grapevine shoots, trunk and roots analysed for 9 different rootstocks. Significant differences (P < 0.01) were found among rootstocks. 8B and Rupestris du Lot rated best in terms of root length, root scale and root number (P < 0.01). Highest shoot length, shoot diameter (P < 0.01) and internode length were obtained, respectively, with the 110R, 8B and Rupestris du Lot rootstocks (P < 0.05). Rupestris du Lot also produced the grapevines with the highest total leaf area per plant and main shoot, whereas the grapevines grafted on 8B had the highest unit leaf area (P < 0.01). Sugar, starch and carbohydrate contents (%) of the different plant parts also varied significantly by rootstock (P < 0.01), with the highest root carbohydrate content measured in the 5C (22.4 %) rootstock, and the highest trunk and shoot carbohydrate content measured in the 110R (12.1 and 13.4 %, respectively). In sum, the study found the best rootstocks for 'Merzifon Karasi' to be 8B, Rupestris du Lot and 110R in terms of root and shoot growth, whereas 'Merzifon Karasi' grape grafted onto 110R and 5C rootstock had the highest carbohydrate contents.