Ecophysiology and vine performance of cv. "Aglianico" under various training systems

A 2-year study was conducted to evaluate ecophysiological characteristics and yield-quality performance of cv. "Aglianico" (Vitis vinifera L.) grapevines trained to three different trellises at the same intrarow vine spacing and bud load per meter of row length. Bilateral guyot (BG) showed the lowest vine capacity and bilateral spur-pruned cordon (BSPC), with a vertical shoot positioning had the highest total leaf area (LA) and pruning weight. Despite very comparable crop levels among trellises, quality decreased considerably in the bilateral free cordon (BFC) vines with respect to the systems with upright shoot growth. BFC vines showed significantly lower sugar concentration (degrees Brix), anthocyanins and phenols, and higher pH and K+ according to a pattern frequently associated with excessive within-canopy shading. Shading was aggravated in the BFC vines by canopy rotation, which probably resulted in an increase of LA density per volume unit. Moreover, the BFC canopies had more close-to-horizontal oriented leaves and from veraison onward, placed the most functional median and apical leaves in the lower or less illuminated portion of the canopy. These factors may have combined to diminish total vine photosynthesis in BFC-trained vines. The data also pointed out that the differences among trellises could not have been predicted simply on the basis of widely accepted indicators of crop load (e.g. the yield-to-pruning weight ratio) or canopy density (e.g. leaf area-to-canopy surface area (LA/SA)). (C) 2001 Elsevier Science B.V. All rights reserved.