Variability in the ripening and maturation of fruit impacts its composition and ultimate quality. A study was conducted in 2006 and 2007 in two commercial vineyards in the Finger Lakes area of New York to assess the degree of biological variability in the commercially important red grape varieties Concord and Cabernet franc (CF). Vines, clusters, and berries were examined for variability in berry size, deformability or softness, color, cluster weight, and soluble solids by calculating the coefficient of variation. Variability was highest early in fruit development and decreased considerably by harvest. Berry diameter variability at harvest was as high as 11% in CF, while deformability varied as much as 38% in Concord. Variability in cluster weight in CF was as high as 45%, while soluble solids variability in Concord reached 14%. Variability in berry diameter, deformability, and color was higher in Concord than in CF, while fruit soluble solids and cluster weight variability was higher in CF. Within individual clusters, berries from the bottom third of the cluster were considerably higher in soluble solids than berries sampled from the top third. These results are valuable to growers seeking to improve uniformity of grape ripening in a vineyard, optimize preharvest sampling strategy, and select and retain only the highest quality fruit on a cluster for juice or wine production.
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