Early defoliation reduces cluster compactness and improves grape composition in Mandó, an autochthonous cultivar of Vitis vinifera from southeastern Spain

• Mandó is a minor variety from Spain used for elaborating premium quality wines.
• A 3-seasons long experiment assessed effects of early defoliation on grape quality.
• Three timings: just before anthesis, at flowering, and at fruit set, were tested.
• Defoliation at fruit set reduced cluster compactness and improved grape composition.
• Berry tasting was also improved by early defoliation.

In the old-world viticulture autochthonous varieties are an important inheritance because they can provide wines with authenticity and distinction. Cultivar Mandó is an almost extinct variety from southeastern Spain, which is used by a few wineries for elaborating premium quality wines. The aim of this 3-seasons long experiment was to assess the usefulness of early defoliation to reduce cluster compactness and to improve grape composition. Early defoliation, consisting of removal of all leaves from the first eight nodes, was tested at 3 different timings: just before anthesis, at flowering, and at fruit set. Non-defoliated vines were considered as a control. Yield and grape composition parameters were evaluated. Early defoliation, especially at fruit set, reduced cluster compactness and yield but increased total phenolics, anthocyanins and tannins concentration in berries. In the three seasons, total soluble solids concentration showed a tendency to increase in defoliated vines, while titratable acidity and pH were not clearly affected by the leaf pulling applications. Berry tasting was also improved by defoliation. As a consequence, defoliation carried out at fruit set is now widely conducted in the Mandó vineyards in the area for premium wine production.