Characterizing Berry Quality in Five ‘Merlot’ Clones from the Hexi Corridor Region of China Through GC-MS and Metabolomics

Clonal selection is essential for adapting wine production to specific terroirs. To characterize clonal variation in berry quality, five ‘Merlot’ clones (M343, VCR1, VCR3, VCR13, and VCR101) grown in the Hexi Corridor region of Gansu Province, China, were evaluated during the 2024 growing season. An integrated analysis of morphological, physicochemical, phenolic, metabolomic, and volatile traits was conducted to provide a multidimensional assessment of clone-specific berry quality under the arid conditions of this region. VCR1 exhibited the highest total soluble solids and anthocyanin contents, alongside the largest number of annotated metabolites. VCR101 had the highest titratable acidity and the most diverse flavonoid profile, whereas VCR13 showed the highest total soluble sugar content. VCR3 had the highest tannin and total phenolic contents and also exhibited the greatest number and total semi-quantitative relative abundance of volatile compounds. These findings demonstrate that, under arid conditions, the clones differ in their accumulation patterns of sugars, organic acids, phenolics, and aroma-related metabolites. Exploratory principal component analysis identified VCR3 and VCR1 as promising candidates for production objectives emphasizing different quality attributes. These findings provide practical information for clonal selection, germplasm evaluation, wine grape breeding, and region-specific cultivation under arid environmental conditions.