Corvina and Corvinone grape berries grown in different areas and their aptitude to postharvest dehydration

The Valpolicella area (Veneto Region, Italy) is famous for its high quality wines: Amarone and Recioto, both obtained from partial post-harvest dehydrated red grapes. The main cultivars used for these wines are Corvina and Corvinone. In this region hundreds of years ago a particular wine making process was developed to dehydrate the grape after the harvest. The aim of this innovative work was to study how the environmental factors affected the post-harvest dehydration process. Different vocation units were defined from a pedological survey using landscape genesis. Afterwards Corvina and Corvinone vineyards, trained with simple Guyot, were selected and observed for a three year period (2009-2011). New parameters correlated to grape dehydration rate were evaluated: quantity of epicutiuolar wax (Ew), skin thickness (ThS), bunch density (BD) and berry surface to volume ratio (S/V). The results showed a variation of these parameters depending on the environmental variability, mainly due to pedological soil characteristics (texture, depth, soil water availability), site-altitude and exposure. The Ew, BD and S/V showed a good correlation with the kinetic of post-harvest weight loss, so the evaluation of these parameters can be used as a prediction model. This new information is useful for winemakers so they can separate the grapes depending on the growing area to reach an optimum post-harvest weight loss (from 35% to 45%).