Within-season temporal variation in correlations between vineyard canopy and winegrape composition and yield

Remote optical imaging can rapidly acquire information describing spatial variability in vineyard block performance. Canopy characteristics were derived from very high spatial resolution (0.25 m) optical imagery of a Cabernet Sauvignon vineyard acquired at various canopy growth stages. Within-season changes to correlation coefficients between vineyard canopy and ultimate composition and yield of harvested fruit were then investigated. Canopy area and density were observed to have significant relationships with yield and fruit quality indicators including berry size, anthocyanins and total phenolic content, but less significant relationships with total soluble solids. The strength and type of correlation varied with canopy growth stage. For anthocyanins and total phenolic content, correlations varied from non-significant before flowering to negative after flowering. For berry weight and yield, correlations varied from negative before flowering to positive after flowering. For total soluble solids, there were some significant relationships but no clear temporal pattern. The results confirm that remote sensing is a useful tool to determine spatial variability in fruit composition and yield. However, both the timing of image acquisition and the way in which canopy is quantified are important determinants of the direction and strength of correlations with fruit composition and yield.