Effects of Different Rootstocks on the Physicochemical Properties and Aromatic Compounds of ‘Cabernet Sauvignon’ Wine

This study assessed how rootstocks affect the physicochemical traits, sensory quality, and aroma profile of ‘Cabernet Sauvignon’ (CS) wine to guide rootstock selection in arid regions. Self-grafted vines (CS/CS) were the control, and five combinations (CS/5BB, CS/140R, CS/5C, CS/SO4, CS/kangzhen3) were vinified using standard procedures. Physicochemical indices, CIELab colour, and sensory attributes were evaluated; volatiles were analysed by HS-SPME-GC-MS and interpreted using PCA, OPLS-DA, and OAVs. All wines met national dry red wine standards. CS/SO4 showed the best overall physicochemical quality (composite PCA score 4.167, ranked first) and significantly higher dry extract, total sugar, soluble solids, and resveratrol than CS/CS. CS/5BB had the highest total semi-quantitative aroma compound content (53,278.32 μg·L−1) and the greatest ester proportion (42.85%), exceeding the other treatments (10.98–38.61%). Ninety-four volatiles were identified; 13 compounds exhibited OAV > 1, mainly esters (ethyl butyrate, ethyl hexanoate, and ethyl octanoate) and aldehydes (hexanal and heptanal) imparting fruity, floral, and green notes. OPLS-DA identified 15 discriminant compounds (VIP > 1), including ethyl acetate, phenethyl alcohol, and isopentanol. CS/5BB and CS/5C were enriched in floral/fruity esters, whereas CS/140R and CS/CS showed stronger vegetal/chemical notes. Rootstock significantly altered physicochemical properties, colour, antioxidant capacity, and aroma; CS/SO4 may improve balance and ageing potential, while CS/5BB enhances aroma complexity and fruit expression. As the data were obtained from a single vineyard site and a single harvest year, these findings require validation in multi-year trials.