## 3 Results
### Volatile Compounds and Their OAVs in Wine and Sensory Tasting  
OAVs, a quantitative metric for assessing volatile compounds' contribution to wine aroma profiles [37], were determined for detected volatiles. The OAV of each compound was derived by dividing its experimental concentration by the corresponding sensory perception threshold documented in established literature sources. And OAVs were calculated by dividing the concentrations of volatile compounds in wines by their sensory thresholds. Aroma compounds with OAVs > 1 were generally considered to be clearly perceived by the panelists [38]. In this study, we identified 18 compounds with OAVs > 1, which included 7 types of esters, 3 types of higher alcohol, 2 types of benzene compounds, 2 types of terpene compounds, 2 types of C13-norisopenoids, and 2 types of acid (Table S9). \(\beta\)-damascenone, a volatile molecule with high OAVs, smells like honey, tropical fruit, quince, and apple and may indirectly affect wine fragrance by amplifying the fruity notes of ethyl esters [39]. OAVs for \(\beta\)-damascenone did not differ significantly among graft combinations in 2019, but SO4 improved OAVs significantly in 2020 (Table S9). 1-hexanol,  
Figure 4: PCA based on aromatic substance concentrations of grapes in three vintages (2018–2020) (**A**); OPLS-DA based on aromatic substance concentrations of grapes in two vintages (2019–2020) (**B**). Note: The four-pointed red stars represent the differential compounds (VIP > 1), the specific names of which are shown in Supplementary Materials Table S8. The results of the 200 cross-validation results are shown in Supplementary Materials Figure S3. as the only C6 alcohol substance with OAVs > 1, contributes herbaceous, grassy, and woody aromas that could be intuitively perceived by wine panelists. The OAVs of 1-hexanol were significantly higher in CS/1103P wines than in CS and other graft combinations over two consecutive vintages, indicating that 1-hexanol is a key substance influencing the greenness of the wine. It is encouraging to see that CS/1103P had a higher green flavor score in the sensory tasting (Figure 6), which was consistent with our inferred results based on aroma substances with OAVs > 1. CS had the highest overall berry score, but there was a slight difference between the two vintages, with CS having the highest red berry score in 2019 and CS having the highest black berry score and flower flavor in 2020, which might be caused by more esters in CS wines. It has been shown that ethyl propionate, ethyl 2-methylpropionate, and ethyl 2-methylbutyrate give wines more black berry flavors, while ethyl butyrate, ethyl caproate, ethyl caprylate, and ethyl 3-hydroxybutyrate give wines more red berry flavors [40]. While CS/5A had a lighter green flavor, it received the highest overall evaluation score among all samples. Through sensory evaluation, 1103P did add a green flavor to the wine, and the substance that contributed to the green flavor, among the OAVs > 1 was 1-hexanol. Interestingly, OPLS-DA also showed that 1-hexanol was the differential compound between CS/1103P wines and CS wines (VIP > 1), and the ANOVA also showed that CS/1103P wines had significantly higher levels of 1-hexanol than CS wines (Table S6). Therefore, we could conclude that 1-hexanol was the key GLV that distinguishes CS/1103P wines from CS wines. This difference was also reflected in the grape. A study also indicated that 1-hexanol was considered a secondary source of differences among four grape varieties [41]. In addition, it was found that the influence of 1103P on aroma was always concentrated on the C6/C9 substances in the grapes. Therefore, we  
Figure 5: PCA based on aromatic substance concentrations of wine in two vintages (2019–2020) (**A**); OPLS-DA based on aromatic substance concentrations of wine in two vintages (2019–2020) (**B**–**E**); network diagram based on differential compounds (VIP > 1) in three rootstock combination wines (**F**).