Effects of spur or cane pruning on fruit composition of ‘Cabernet Sauvignon’ grapes

During the 2011-2012 season, a trial was conducted on mature 'Cabernet Sauvignon' vines in San Bernardo, Región Metropolitana, Chile, on a Mediterranean climate. The design was completely randomised blocks, with 12 replicates, and each vine corresponded to a block. The six-year old vines were trained to a bilateral cordon and pruned to 16 buds per vine. Randomly, one side was pruned leaving 4 spurs with 2 buds each; the other side was pruned to one 8-bud cane. The budbreak percentage, shoot growth, fruit yield and soluble solids, titratable acidity and pH of fruit were evaluated. On 100 berry skins, total anthocyanin content, and skin and seed total phenols and total tannins were measured by spectrophotometry, with anthocyanin and phenol composition measured by HPLC-DAD. Additionally, a fruit sensorial analysis was done at the time of harvest. The following winter, pruning weight was registered. Total shoot growth and average shoot length at the beginning of the season were higher on the spur-pruned treatment. Pruning weight was also superior on spur-pruned cordons. Although bud break was significantly higher on spur-pruned cordons, total fruit weight was the same between treatments. Cluster weight was statistically not different between spur and cane pruned cordons. Soluble solids, pH and TA were also similar between treatments. Total phenols, anthocyanins and tannins in the skins and seed phenols and tannins were not different between spur and cane treatments. Phenol composition showed no differences in skin or seeds from the fruits of each treatment. Sensorial analysis was similar for both treatments. The results for fruit parameters suggest that either pruning system can be used for optimal yield and fruit quality.