Influence of intensity of post-veraison defoliation or shoot trimming on vine physiology, yield components, berry and wine composition in Aglianico grapevines

Background and Aims: Post-veraison trimming and defoliation have been proposed as strategies to decrease the concentration of berry carbohydrate at harvest and of wine alcohol, but it is unclear which of these two pruning techniques is more suitable and at what intensity they should be applied. The aim of this 3-year study was to compare the suitability of two intensities of post-veraison trimming or defoliation in controlling sugar accumulation in the berries of Aglianico grapevines. Methods and Results: Five treatments were compared: two intensities of defoliation, two intensities of shoot trimming and a control. All pruning treatments decreased berry TSS at harvest and wine alcohol concentration. Defoliation and trimming of moderate intensity also improved wine sensory score, whereas intense defoliation and trimming can affect negatively this parameter. Conclusions: Post-veraison defoliation and trimming of moderate intensity appear to be suitable strategies for decreasing berry TSS at harvest and wine alcohol concentration. Significance of the Study: The selection of the correct intensity of leaf removal appears to be one of the critical factors in correctly designing a suitable strategy of post-veraison summer pruning that aims to decrease sugar accumulation in the berries, whereas the choice of the type of pruning appears to be less crucial.