Partitioned harvesting based on vineyard row orientation revealed the nexus between intra-vineyard heterogeneity and polyphenol levels in Cabernet Sauvignon grapes and wines

Phenolics are essential bioactive components that determine the appearance and taste characteristics of wines. The biosynthesis of grape phenolics is sensitive to vineyard microclimate conditions, which profoundly affects vineyard precision management. This study aimed to clarify the effect of partitioned harvesting based on vineyard canopy sides on grape and wine phenol levels. Parallel field experiments were conducted in four Cabernet Sauvignon vineyards with different row orientations across three seasons. Results showed that vineyard row orientation directly affected temperature-solar radiation distribution and spectrum in the cluster zone, ul- timately affecting grape phenolics. Grape sugar content varied significantly in various canopy positions, which were associated with the photosynthetic capacity of grapevines. Partitioned harvesting significantly altered the distribution of anthocyanins and flavonols in grapes. Grapes and corresponding wines from exposed canopy sides showed higher flavonol concentrations than the shaded canopies, while anthocyanins varied, which were associated with temperature-solar radiation distribution around the cluster zone. Acylated anthocyanins and kaempferol-based flavonols showed high and significant correlations with the row orientations through regression models. The canopies with more heat stress produced wines with higher pH and lower anthocyanin levels. The different expressions of flavonoid pathway genes were responsible for the anthocyanin-flavonol distribution patterns related to partitioned harvesting. The find- ings of this research provided a better understanding of vineyard precision management.