Successful technology transfer of the early defoliation technique in cv. Mandó, an autochthon variety from south-east Spain

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 extinguished variety from the south-east of Spain with very large and tight clusters. In addition, it is quite late-season ripening. Celler del Roure winery is using Mandó grapes for premium quality wine production. The winery commonly employs cluster thinning to reduce crop level and, at harvest, only the fully healthy clusters are picked. Indeed, around 50 %of the initial crop is then not used for wine-making. The aim of this study was to asses the usefulness of early defoliation as a possible tool to reduce cluster compactness, improving fruit composition and reducing the labor costs associated with cluster thinning. With this in mind, an experiment was conducted with cv. Mandó in deficit irrigated vines trained with a divided Lyra system. Control (C), un-defoliated vines, were compared with de-foliation 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, fruit set, berry weight and yield were reduced by 44, 16 and 45 %, 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 with a berry tasting panel. In agreement, berries from the ED and LD also had higher total phenolics, anthocyanins and tannins concentration. Results obtained were judged positively by the winery owners and defoliation, particularly at stage J, will be now more widely conducted in the vineyards planted with the Mandó variety. This is because the detrimental effects of defoliation on yield were similar to the crop reduction previously needed when cluster thinning and selection had to be carried out. The research is indeed an example of a successful transfer of a research technique under commercial situations.