engleski

Manipulation of cv. Teran grape and wine quality with severe shoot trimming and cluster thinning

Accelerated grape ripening with the ensuing high wine alcohol concentration has become widespread problem in various grape growing regions in the recent years. One possibility of adaptation to this emerging problem can be obtained by different canopy management practices in the vineyard. In this study the effects of severe shoot trimming and cluster thinning on grape ripening and grape and wine quality of cv. Teran were investigated, with the aim to find a canopy management practice which will result with lower wine alcohol concentration, without affecting the phenolic composition of grapes and resultant wines. In a Teran vineyard, two different shoot heights (70 and 130 cm), obtained by shoot trimming at the beginning of veraison, were combined with cluster thinning ; with cluster thinning applied at the beginning of veraison (CT) or without cluster thinning (NO CT). At earlier stages of ripening, higher differences in soluble solids among treatments were observed, with severe shoot trimming having larger impact than cluster thinning. With approaching to full maturity, the differences among treatments still remained, but were less pronounced than in earlier stages. The lowest alcohol, total anthocyanins and total phenolics concentrations in wines were achieved with 70 cm/NO CT treatment, while the highest values were achieved with 130/CT treatment. While 70/CT treatment had lower soluble solids in grapes and alcohol concentration in wine than 130/NO CT treatment, the opposite trend was observed with total anthocyanins in grapes and wines, which were higher in 70/CT than in 130/NO CT treatment, and in 70/CT treatment reached almost the same values as in 130/CT treatment. Both severe shoot trimming and cluster thinning can be effectively used in order to manipulate cv. Teran grape and wine quality, taking into account both the desired wine composition and the yield loss as a result of cluster thinning.

canopy management; leaf area/yield ratio; grapevine; phenolics; anthocyanins

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