EFFECTS OF LATE MECHANIZED LEAF REMOVAL ABOVE THE CLUSTERS ZONE TO DELAY GRAPE RIPENING IN 'SANGIOVESE' VINES

The responses to late season mechanical leaf removal (four weeks after verasion) conducted above the clusters zone in ‘Sangiovese’/3309 C vines trained to spur-pruned cordon were assessed in 2011 as grape composition, wine quality and replenishment of the reserve in roots and stems. Eliminating 36% of the more functional leaves (i.e. median leaves and a fraction of well-expanded apical leaves of either primary and lateral shoots) resulted an effective, easy-to-do and economically viable method (it required only 3-4 hours per hectare) to slow grape ripening and obtain grapes with reduced soluble solids concentration and wine with lower alcohol content (-0.6%). Concurrently, the concentration of phenolics compounds in the grapes, the chemical and chromatic characteristics of the wines and the replenishment of the reserves (alcohol-soluble sugars, starch and total nitrogen) in the stems and roots were unaffected as compared to the non defoliated vines. This preliminary data also suggest that, in ‘Sangiovese’, a robust response can be achieved if leaf removal is performed when the soluble solids concentration in the berries ranges around 15-16 °Brix and while severity of defoliation should not be less than 35-40% of the pending total leaf area.