Interaction “training system x cluster thinning”: effects on yield and quality, cv. Baga, in Bairrada region

Abstract

During the growing season of 2007, in Bairrada region, were compared the effects of the training system and cluster thinning on the agronomic and ecophysiological behaviour of the Portuguese red variety Baga, grafted onto 3309C rootstock. Two training systems: LYS:  the transversal cut of the canopy is similar to an inverted “Y” (Mota, 2005),   and vertical shoot positioning-VSP) and four cluster thinning treatments were assayed (CT1 – no cluster thinning; CT2 – 1 cluster per shoot at pea size was left; CT3 – 1 cluster per shoot at veraison was left and CT4 – qualitative cluster thinning). A “split-plot” experiment with two replications was designed. The LYS training system, presented by Castro et al. (1995), with lower fertility index and predawn leaf water potential, that indicates higher water consumption at root zone and lower values of net photosynthesis during the ripening, originated similar yield to VSP. The wines from LYS, presented higher   yield and the titratable acidity, and increased the cluster weight and the sugar content. The interactions LYSxCT2 and LYSxCT4 showed the highest values of sugar content, and even without cluster thinning (LYSxCT1), the LYS training system reached similar values of sugar content relative to VSP with cluster thinning, but with higher yield (ca. 50%).