Rootstock-mediated effects on vine performance and quality composition of ‘Miguang’ under protected cultivation in northern China

Abstract “Miguang” (MG) is a muscat-flavored table grape ( Vitis spp.) widely planted in China; the cultivated areas in China of MG have rapidly increased due to its early ripening period, good taste, and attractive appearance. To provide comprehensive information to vine growers on the selection of a suitable rootstock, we studied the effects of six rootstocks (SO4, 110R, 3309, 101-14, Valiant, and 5BB) on the grafted vine growth, yield, berry physiochemical parameters, and volatile compounds of MG in two successive seasons. Although the vine vigor (defined as pruning weight) was not significantly affected by all tested rootstocks, the yield was significantly decreased in the combinations with the rootstock of 101-14 (21% and 24% less than own-rooted vines in 2021 and 2022, respectively). SO4 had a remarkably adverse effect on the berry color (with a higher h° value), and 101-14, Valiant, and 5BB exerted a notably positive influence on the berry color (with a lower h° value). Berry hardness and pulling resistance (PR) were significantly improved by Valiant (hardness, 24% and 20% more than own-rooted vines in 2021 and 2022, respectively; PR, about 10% more than own-rooted vines in both seasons). Although bunch weight and berry weight were not remarkably altered by those tested rootstocks, total soluble solids (TSS) were notably reduced, and titratable acidity (TA) was significantly improved by SO4. The volatile esters and terpenoids both greatly contribute to the fruity and floral aromas of grapes, and the total amount of ester was not notably affected by those tested rootstocks; the total terpenoid content was significantly reduced by rootstock SO4 in both years (16% and 21% less than own-rooted vines in 2021 and 2022, respectively). Although the total terpenoid content was not obviously affected by Valiant, the accumulation of linalool, one key terpenoid for grapes, was significantly improved in both seasons (22% and 23% more than own-rooted vines in 2021 and 2022, respectively). In conclusion, Valiant determined an improvement in the berry color, hardness, PR, and linalool content, and it was a suitable rootstock for MG. Significance of the study What is already known on this subject? Grafting is commonly used in viticulture to enhance vine resistance against biotic and abiotic stresses. However, the influence of rootstocks on vine fruit quality, especially on volatile compound content, remains controversial and not fully understood. Previous studies have shown inconsistent results regarding the effects of rootstocks on vine vigor, yield, and berry composition, such as sugar, acidity, and anthocyanins. The effects also vary depending on factors such as soil type, environmental conditions, and scion cultivars. What are the new findings? In this study on 'Miguang' grapevines, it was found that different rootstocks had diverse effects. Although vine vigor (pruning weight) was not significantly affected by all tested rootstocks, the yield was significantly decreased in the combinations with the rootstock of 101-14. SO4 had a negative impact on berry color (higher h ° value), while 101-14, Valiant, and 5BB improved it (lower h ° value). Berry hardness and pulling resistance (PR) were enhanced by Valiant. Regarding the basic physiochemical parameters, bunch weight and berry weight were not notably changed by the rootstocks, but SO4 reduced total soluble solids (TSS) and increased titratable acidity (TA). In terms of volatile compounds, the total terpenoid content was significantly reduced by rootstock SO4, while Valiant improved the accumulation of linalool, a key terpenoid for grape flavor. What is the expected impact on horticulture? The results provide valuable information for vine growers in selecting suitable rootstocks for “Miguang” grapevines. They can make more informed decisions based on the desired characteristics such as improved fruit quality (color, hardness, flavor) or stable yield. It emphasizes the importance of considering rootstock/scion combinations not only for stress resistance but also for enhancing fruit quality. This could lead to the development of more sustainable and high-yielding viticulture practices by optimizing rootstock selection. Future research directions are suggested, such as exploring the long-term stability of beneficial rootstock effects across different environments and investigating the interaction between rootstocks and soil microbiota, which could further contribute to the improvement of grape quality and vine health in horticulture.