Effects of vineyard inter-row grass cover treatment on microbial diversity and metabolite profiles during Cabernet Sauvignon fermentation

Inter-row grass cover is an ecological management strategy that profoundly affects vineyard microecology, yet its effects on fermentation-associated microbial diversity and wine metabolites remain incompletely elucidated. This study compared the effects of inter-row clean tillage (CK) and inter-row grass cover (CG) in vineyards on grape quality, microbial diversity during wine fermentation, and the metabolite profile of wine. Compared with CK, CG significantly improved grape quality, with soluble solids, reducing sugars, total phenolics and anthocyanins increasing by 5.75, 6.33, 15.85, and 11.12%. CG increased the relative abundance of Saccharomyces in the initial must by 45.21% and decreased Gluconobacter by 78.78%, while maintaining higher microbial diversity during fermentation. CG wines are rich in esters, with more pronounced characteristic aromas of dark berry, floral, toasty, mineral and spicy notes. PLS-DA identified 26 differential metabolites enriched in amino acid, organic acid and fatty acid metabolism. Key taxa, including Saccharomyces , Hanseniaspora , and Lactobacillus were significantly positively correlated with differential metabolites. In summary, inter-row cover cropping was significantly associated with shifts in fermentation microbial community structure, differential expression of core metabolic pathways, and variations in wine volatile metabolites. This study provides a potential ecological vineyard management strategy for modulating wine sensory properties.