Productive behavior and composition of the must of cv. Tempranillo depending on the cluster size with different crop level

Abstract

Cluster weight is one of the yield components that most influences the production. The relationship between productive level and grape quality is one of the main topics of discussion among the agents of the wine sector. To provide database to study this topic a trial was carried out during the years 2012, 2013 and 2014, analyzing the characteristics of two types of clusters: large (> 300 g weight) and small (< 200 g weight). The clusters come from vines of three crop level treatments: 6,500, 9,500 and 12,500 kg/ha. The vines  of  the  experimental  vineyard  are  of  cv  Tempranillo  planted  in  2002  and  grafted  onto  rootstock  110R. The experimental vineyard is located in Fermoselle (Zamora), belonging to the A.O. Arribes, mostly with acid pH soils. The planting density is 3,330 vines/ha (3 x 1 m). The vines were trained to a vertical trellis with bilateral Royat cordon and vertical shoot positioning (VSP). The pruning load was 12 buds/vine distributed in 2 buds spurs. The three crop level treatments were fixed through cluster thinning at the beginning of the veraison. The results have shown that there are no big differences in grape quality parameters and grape colour parameters between the two types of clusters. The differences between different cluster size (large vs. small) as a whole weren´t significant in the soluble solids, or in the total acidity nor in aspects related to the colour. The differences are small in grape quality among different crop level. The cluster average weight and the berry weight showed differences between the two lower crop level and higher crop level. As a whole, the differences were significant neither in the productive parameters nor in the grape quality. Therefore, the crop level could be increased until a certain threshold, because the results have shown that have not changed substantially the basic components of the grape. It seems that it is more important the status of the vine within a crop level than the cluster size within a vine.