Effects of Vineyard Management Practices on Winegrape Composition. A Review Using Meta-analysis

Background and goals: Various vineyard management practices are designed to improve production outcomes such as fruit quality and disease prevention. Meta-analysis was used to investigate the effects of vineyard practices on grape composition to better inform vineyard managers of likely outcomes and support the selection and application of the practices. 

Methods and key findings: A meta-analysis was used to investigate a range of vineyard practices (cluster thinning, irrigation, leaf removal, pruning timing, pruning severity, shoot thinning, and shoot trimming) and their effects on grape composition parameters (total soluble solids [TSS; sugars], pH, titratable acidity [TA], anthocyanins, tannins, and total phenolics), the ratios of TSS and TA and pH and anthocyanins, and the production of TSS and anthocyanins per hectare. The results varied depending on the timing and severity of the practice. Increases in anthocyanins and total phenolics were more substantial than increases in TSS. For most practices, despite increased TSS and anthocyanins, their production per hectare decreased. 

Conclusions and significance: This meta-analysis provides information valuable to assist grapegrowers and wineries in predicting the outcomes of various vineyard management practices on grape composition. Although many of these practices improved fruit composition, productivity decreased, whether measured as yield or TSS and anthocyanins per hectare. This could lower economic return for the grower and must be considered when designing grape payment schedules.