## 4 Discussion  
In most wine grape-producing regions of northern China, the average winter temperatures drop below \(-15\)\({}^{\circ}\)C, making dormant freeze damage an unavoidable natural hazard in northern wine grape-producing regions [24]. Consequently, overwintering frost damage has become a critical concern in the wine grape industry [25]. Studies have shown that wine grapes from the Mediterranean region, such as Cabernet Sauvignon, are vulnerable to branch freezing damage at temperatures between \(-16\)\({}^{\circ}\)C and \(-18\)\({}^{\circ}\)C [26]. Among the seven overwintering treatments proposed in this study, only the thickened striped cloth and heat-insulating striped cloth treatments had temperatures exceeding -16 \({}^{\circ}\)C at the branches on the coldest day during the overwintering period, which would lead to lethal freeze damage to the wine grape branches. The remaining five overwintering treatments did not pose a risk of freezing death to the grape branches during the overwintering period. The average temperature and the temperature on the coldest day at the branches with the sandwiched striped cloth and double-layer striped cloth treatments were both higher than those with the striped cloth treatment, indicating that the heat preservation ability of the two treatments at the grape branches was stronger than that of the striped cloth treatment. Notably, lower overwintering temperatures increased osmotic stress and reactive oxygen species accumulation in the wine grape branches, exacerbating potential damage [25]. Dividing the study into temperature intervals during overwintering revealed that the sandwiched striped cloth and double-layer striped cloth treatments resulted in longer durations within the low-temperature transition zone than the striped cloth treatment. This extended exposure facilitated the accumulation of osmotically regulated substances and enhanced antioxidant enzyme activity, enabling the wine grape branches to better withstand severe cold stress [27]. Prolonged exposure to this temperature range was also found to support the safe winter survival of the grape branches [28]. Consequently, the sandwiched striped cloth and double-layer striped cloth treatments were more effective in ensuring the safe overwintering of the wine grape branches. Additionally, branch desiccation during over  
Figure 11: Wine grape yield (**a**) and soluble solids content (**b**) under different overwintering treatments (A: soil-covered striped cloth, B: striped cloth, C: sandwiched striped cloth, D: thickened striped cloth, E: double-layer striped cloth, F: heat-insulating striped cloth, G: heat-insulating sandwich striped cloth). Letters (a, b, c, d) indicate significant differences (\(p<0.05\)) between treatments for each measured parameter. wintering significantly affects grapevine growth and yield in subsequent years [29]. This study implemented seven overwintering treatments designed to maintain humidity above 88%, effectively preventing branch dehydration. The analysis of the temperature fluctuations on 19 December, the coldest day of the overwintering period, demonstrated that the temperature variations in the wine grape branches were influenced by solar radiation and ambient temperature. Large temperature fluctuations during dormancy increase osmotic stress and reactive oxygen species production, negatively affecting the safe overwintering of the wine grapes [30]. Among the treatments, only the sandwiched striped cloth treatment demonstrated smaller daily temperature ranges and less temperature fluctuation than the striped cloth treatment, making it more effective in ensuring the safe overwintering of the wine grapes. The root system of wine grapes is more susceptible to low temperatures than the branches, with the critical temperature for frost damage in Cabernet Sauvignon roots being \(-4\)\({}^{\circ}\)C [12]. During the winter, snow accumulation reduces the solar radiation on the land surface, causing energy dissipation within the soil [31].