Yield components, vegetative expression and physiologic indicators on Vitis vinifera L. cv Merlot depending on plant architecture

Abstract

A study with reference to trellis system effects on the yield components, vegetative expression, physiological indicators and water status regulation was carried out from 2001 to 2004 in the principal wine-growing region of Uruguay. The experiment was performed in a commercial Merlot vineyard, grafted on SO4. The plants were trained to a Lira and high Vertical trellis, Royat pruned with an average number of 18 buds by plant. As an alternative, a cluster thinning was practiced at veraison with an intensity of 50 % in relation to control plants. Yield per plant and per hectare was significantly superior on the Lira than on the Vertical trellis. The potential leaf exposed surface and the total leaf surface presented significantly higher values in the Lira. Pruning weight and shoots length, were significantly superior in the Vertical trellis. The leaf surface per cluster kilogram was higher in the Vertical trellis, whereas the Physiological Indicators showed more balanced plants in the Lira. Along the years of this study, the predawn leaf water potential, according to fenological states, showed that registered values for Lira architecture were significantly lower than those the Vertical trellis, and placed in ranges of moderate stress. Plant architecture had a determinant influence on yield components, vegetative expression and plant water status regulation. The Lira trellis system appeared as a valuable tool to regulate the water consumption, and to obtain higher yields, keeping more balanced plants. Globally, this training system presented comparative advantages for the Merlot cultivar in the agroecological conditions of the climatically delimited ISA₁ IHA₃ IFA₂ zone of Uruguay.