wines are widely made in the dry-hot wine region valleys in Shangri-La. For example, in Weixi county (Diqing, Yunnan Province), Vidal grapes are always harvested at the end of December or early January, when the total soluble solids exceed 30\({}^{\circ}\) Brix by on-vine natural dehydration, with which late-harvest dessert wines are made. However, the volatile compound profile of Vidal grapes in this region has not been extensively investigated to date, especially regarding the late-harvest on-vine dehydration process.  
It is well-known that wines made from late-harvested or post-harvest dehydrated grapes have higher sugar levels and more intense flavors than wines made from grapes of normal maturity [9; 10]. Many researchers and winemakers attribute these results to the dehydration and concentration effect of the grape berries during these processes [11]. Indeed, the pre-fermentation 'concentration' process (either natural or artificial) not only concentrates the grape juice, but also changes the grape's secondary metabolism and the content of flavors, ultimately affecting the sensory quality of the final wine [12]. The pre-fermentation dehydration process includes both on-vine (over-ripening, icing, and _Botrytis_) and off-vine (natural and artificial drying) processes [10]. The evolution of volatile compounds is determined by many factors, such as the dehydration model (on-vine or off-vine) [13], grape variety [14], water-loss technology [15], drying temperature [16], environmental factors [10], and even the microeukaryotic community [17]. Oxidation and anaerobic metabolism have also been observed in grape berries during the off-vine dehydration and on-vine icing processes [18; 19; 20].  
It should be pointed out that the berry dehydration that happened during the late-harvest process of noble-rotted and icewine grapes is actually a structurally destructive dehydration process for grape berries. For noble-rotted grapes after _Botrytis_ infection, the pectin of the cell wall is degraded, and the affected tissue is collapsed due to the presence of destructive petolytic enzymes. This structural disruption promotes berry dehydration under dry weather conditions [12]. For icewine making, the grapes undergo a dehydration process and endure several freeze-thaw cycles during the late-harvest freezing process, accelerating disruption of the berry cellular structure and leading to damage to the grape skin wax layer [17; 19; 21].  
As reviewed above, most of the studies in the existing literature have focused on the grape aroma evolution during destructive dehydration and off-vine post-harvest drying processes, while little research has been conducted on the non-destructive dehydration process during on-vine late-harvest. Furthermore, the ecological condition is the main influencing factor on the variation trend of aromatic compounds during grape dehydration [10], and the accumulation of volatile compounds in Vidal grapes of the Weixi high-altitude wine region has not been investigated before. Therefore, the target of this study was to explore the influence of the on-vine non-destructive dehydration degree on both free and glycosidically bound volatile compounds in Vidal grapes. We expect that the results of this study will help winemakers to make better-informed decisions on the final harvest date, regarding the balance between grape juice yield and wine aroma quality.