## 2 Results and Discussion  
### Meteorological Conditions and Grape Physicochemical Parameters  
Meteorological data were collected from two berry-growing seasons in Jieshishan region (Figure 1 and Table S1). As the Cabernet Sauvignon experiment spanned two years, while the Marselan experiment spanned only one year, this comparative analysis will concentrate on the differences in meteorological conditions and their effects during the growing season of Cabernet Sauvignon grapes between the two years. The climate was observed to be warmer in 2022 relative to 2021, with the average daily temperatures registering at 0.5 \({}^{\circ}\)C higher between 1 July and 1 October. Specifically, during the periods from the hard green berry stage to the beginning of veraison and from post-veraison to harvest, the average daily temperatures increased by 1.5 \({}^{\circ}\)C and 1.4 \({}^{\circ}\)C, respectively (Table S1). In 2022, during the veraison stage, there were two days when the temperature peaked above 35 \({}^{\circ}\)C, whereas no such instances were recorded in 2021. The higher temperatures resulted in an accelerated grape-ripening process, which led to an increase in TSS and a decrease in TA in Cabernet Sauvignon grapes in 2022 (Table 1). In 2022, the quantity of precipitation exceeded that in 2021 by 32.1 mm. Additionally, the distribution of rainfall during the berry-development phase exhibited variability between the two years. In 2021, precipitation was primarily observed during the green-berry and ripening stages, while in 2022, it was concentrated during the veraison stage (Figure 1).  
Table 1 presents the physicochemical parameters of grape berries at harvest following cluster-zone leaf removal at various stages. The ANOVA analysis revealed that the leaf-removal treatment exerted a profound effect on the levels of titratable acids (TA) in the berries. In Cabernet Sauvignon grapes, the LR2 treatment resulted in significantly lower levels of titratable acid (TA) compared to the control in 2021. Furthermore, all three periods of leaf-removal treatments significantly diminished TA levels in 2022, with LR2 resulting in the lowest average levels. Moreover, the pH value was found to be significantly lower in the control compared to LR2 and LR3 in 2021, whereas no significant disparity was observed between the treatments and the control in 2022. Despite annual variations, these findings indicate that cluster-zone leaf-removal treatments typically decrease acidity in Cabernet Sauvignon berries and suggest that leaf removal during veraison could be more beneficial. A comparable pattern was observed in the 2022 Marselan berries of Cabernet Sauvignon grapes from the same year, with LR1 and LR2 possessing significantly lower titratable acidity than the control and no significant pH variation between the groups. The observed decrease in berry TA is consistent with the expected effects of leaf removal on bolstering malic acid degradation, as excessive sunlight exposure results in elevated temperatures within the cluster zone [7; 17]. Furthermore, the removal of leaves from the cluster zone did not result in a significant impact on the 100-berry weight or soluble solids content of the grapes.  
Figure 1: Daily maximum, average, and minimum temperatures (lines) and precipitation (histograms) recorded from 1 July to 1 October at the Chateau Langes weather station in 2021 (**A**) and 2022 (**B**). Time axis of Cabernet Sauvignon and Marselan berry development and ripening in 2021 (**C**) and 2022 (**D**).