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

A 2-year study was conducted to evaluate ecophysiological characteristics a nd yield-quality performance of cv. "Aglianico" (Vitis vinifera L.) grapevi nes trained to three different trellises at the same intrarow vine spacing and bud load per meter of row length. Bilateral guyot (BG) showed the lowes t vine capacity and bilateral spur-pruned cordon (BSPC), with a vertical sh oot positioning had the highest total leaf area (LA) and pruning weight. De spite very comparable crop levels among trellises, quality decreased consid erably in the bilateral free cordon (BFC) vines with respect to the systems with upright shoot growth. BFC vines showed significantly lower sugar conc entration (degrees Brix), anthocyanins and phenols, and higher pH and K+ ac cording to a pattern frequently associated with excessive within-canopy sha ding. Shading was aggravated in the BFC vines by canopy rotation, which pro bably 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 o r less illuminated portion of the canopy. These factors may have combined t o diminish total vine photosynthesis in BFC-trained vines. The data also po inted out that the differences among trellises could not have been predicte d 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.