Effects of leaf removal and shoot trimming performed in different periods on cv. Vermentino

Mestrado em Engenharia de Viticultura e Enologia (Double Degree) / Instituto Superior de Agronomia. Universidade de Lisboa / Faculdade de Ciências. Universidade do PortoVermentino is a cultivar traditionally cultivated in the west Mediterranean region; in Italy there are about 5000 hectares with this variety, mainly in Sardinia, Tuscany and Liguria. Each clone has specific characteristics concerning production, disease resistance, agronomic performance. To identify the best techniques to achieve the desire grape composition and quality, a series of treatments were performed in a company located in Sarzana, eastern Liguria: early defoliation (ED), post-flowering defoliation (PFD) for north (PFD-N) and south canopy side (PFD-S), apical late defoliation (ALD) and late shoot trimming (LT) compared with a control (CNTR), trimmed when the shoots exceed the wires placed at the top of the canopy to facilitate the tractors passage. ED reduced powdery mildew damages but leading to a lower TSS at harvest and a greater acidity degradation. PFD-S increased significantly TSS with a strong decrement in acidity. PFD-N led to significant differences for bunch weight, berries number and berries weight resulted lower than control. ALD did not confirmed what reported in literature, showing results similar to the control. LT showed a significant difference delaying sugar accumulation and maintaining higher acidity than control. For future studies, it will be necessary to understand if LT can compromise the future plant reserves for the following seasons; if ALD, tested again, will give significative results and if basal defoliation done without removing all the basal leaves but leaving some of them will achieve all the goals without modifying acidity or pH. In general, considering the results obtained with these treatments and the insufficient information founded in literature, further experiments will be necessary on Vermentino variety to achieve a greater awareness in the management of grapes and wine productionN/