Grafting ‘Red Globe’ (Vitis vinifera) onto Multiple Rootstocks: A Systematic, Multi-Year Evaluation Focusing on Graft Compatibility, Vegetative Growth, and Fruit Characteristics

Selecting appropriate rootstocks can enhance the adaptability and fruit quality of grafted grapevines. However, grafting studies on ‘Red Globe’, one of the major cultivated cultivars, remain limited, particularly those involving long-term and comprehensive evaluations. The present research grafted ‘Red Globe’ onto four rootstocks—‘101-14’, ‘188-08’, ‘110R’, and ‘3309C’—and systematically compared graft union healing following hardwood grafting, field performance of grafted vines, vegetative growth of mature vines, and fruit phenotypic and quality traits across multiple years. The results showed that ‘101-14’ promoted the accumulation of organic acids, which reached 1.1% in 2023, and caused an increased tendency for berry detachment from the peduncle. The RG/110R combination exhibited a higher CFI, 0.8 on average, at the basal section, and promoted shoot thickening. RG/3309C was found to have a larger shoot length exceeding 600 cm, and a significant increase in fruit weight to nearly 13 g. The grafts on ‘188-08’ showed the highest survival rate of 74% among the graft combinations, and enhanced fruit quality, as evidenced by elevated TSS (16 °Brix) and firmer pulp texture, indicating that ‘188-08’ may serve as a valuable rootstock for enhancing the local adaptability and fruit quality of ‘Red Globe’ grapevines.