Valutazione agronomica di viti di Ortrugo (Vitis vinifera L.) sottoposte a differenti tecniche di potatura verde

[Autom. eng. transl.] Ortrugo (Vitis vinifera L.) is a native Piacenza white grape variety that, recently, has aroused considerable interest among winemakers thanks to the easy commercial placement of the wine that is produced, particularly appreciated by local consumers. However, Ortrugo is undoubtedly a difficult variety to cultivate because it is easily subjected to excess production and is characterized by compact clusters which, especially in years with marked pre-harvest rainfall, aggravate the sensitivity towards fungal rots. Furthermore, the effects of climate change on viticulture have further accentuated, and sometimes in a worrying manner, the degradation of organic acids during ripening by imposing harvests that are often too early and associated with a loss of wine typicality. The research, conducted in the three-year period 2011-2013, proposed to: a) define the relationship between production load and grape composition; b) to improve the morphology of the bunch and the berry by comparing the following theses: thinning of the bunches in pre-ripening (DIR), basal defoliation in pre-flowering (DF) and in pre-veraison (DI) and, finally, a untreated witness (T). The main leaves and the eventual females developed from the first six basal knots of the bud were eliminated while the thinning was applied removing 50% of the bunches.