Effects of Early Defoliation in Grape Yield and Quality in 'Mando', an Autochthon Cultivar of South-East Spain
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In the old-world viticulture autochthonous varieties are an important inheritance because they can provide wines with authenticity and distinction. Cultivar Mando is an almost extinguished variety from the south-east of Spain with very large and tight clusters. The aim of this study was to assess the usefulness of early defoliation as a possible tool to reduce cluster compactness, improving fruit composition. With this in mind, an experiment was conducted with 'Mando' in deficit irrigated vines trained with a divided Lyre system. Control (C), non-defoliated vines, were compared with defoliation carried out either just before anthesis (phenological phase H, (Def-H)), at flowering (phenological phase I, (Def-I)) or at fruit set (phenological stage J, (Def-J)). In all the defoliation treatments, leaves from the first eight nodes, including laterals, were removed. The experimental design was a complete randomized block with three replicates per treatment and 24 experimental vines per experimental plot. As an average for all defoliation treatments, berry number per cluster, berry weight and yield were reduced by 44%, 16% and 45%, in Def-H, Def-I and Def-J respectively. Defoliation increased berry soluble solids concentration only in the Def-H treatment. On the other hand, berry acidity was only decreased in the Def-H treatment. In the ED and LD defoliation treatments, leaf pulling improved berry quality determined by a berry tasting panel. In agreement, berries from the ED and LD also had higher total phenolics, anthocyanins and tannin concentration. Results obtained were judged positively by the winery owners and defoliation, particularly at stage J, will now be more widely conducted in the vineyards planted with the 'Mando' cultivar. The research is indeed an example of a successful transfer of a research technique under commercial situations.