Impatto della Variabilità Spaziale/Temporale dei Vigneti sulle Uve Nebbiolo

Abstract Background and Aims: The vigor of a vineyard can vary spatially and temporally due to differences in the physical and chemical properties of the soil. These variations may impact the performance of vines, as well as affect factors such as yield, fruit composition, and ultimately the quality and economic value of the wine produced. This study aimed to assess the influence of variability within a specific vineyard block on both the vegetative productivity and qualitative parameters of the Nebbiolo cultivar. Heterogeneity within the studied vineyard is due to difference in soil, and therefore two different treatments (cluster and berry thinning) were applied to evaluate if both the vineyard soils would mature the grapes while avoiding the ripening delay of sand soil. The winery has been vinifying the grapes separately and selling two different wines from this vineyard with the end goal of vinifying both plots at the same time while keeping only one wine produced for the entire vineyard. The investigation took place in a plot situated in Barolo, Italy, which is under the ownership of Cascina Adelaide. Methods: Vigor variations were assessed by measuring the NDVI (normalized difference vegetation index) using a multispectral camera installed on an unmanned aerial vehicle (UAV). This setup enabled the mapping of the vineyard into two vigor categories: High Vigor (HV) and Low Vigor (LV). The evaluations were conducted during the 2023 season and clarified where exactly marl and sandy soils were predominant within the vineyard. Two rows were randomly chosen for the experiment, one on marl soil and the other on sandy soil. In each row, two different treatments of fruit fining were conducted. For treatment 1 (T1), one cluster was left per shoot and for treatment 2 (T2), two halves of a cluster were left per shoot (cluster was cut in half). At six weeks before harvest, the berry samples from control, T1, and T2 were analyzed to observe the differences in berry weight, sugar content (Brix), pH, and titratable acidity (TA) to do a comparison on both soils. The Tukey test was used to statistically analyze the sampling results. Results: The biochemical analysis reveals that there were no significant differences found between sandy and marl soils. The most significant difference was on sugar accumulation closer to the harvest period on sandy soil, where T1 and T2 almost caught up to the final brix value for the control in marl soil. The acids remained stable during the ripening process and no significant differences were found on pH and TA on the control and treatments for marl and sandy soil. The berry weight had a considerable difference on the first sampling where marl soil had an advantage over sandy soil considering the difference in vigor between the soils. The following weeks no significant differences were observed on berry weight where soils and treatments prevailed similar until harvest. The cluster thinning (T1) and berry thinning (T2) methods in both soils showed, as expected, a significant reduction in total yield compared to controls. Conclusion: This experiment suggests that it is possible to manage the heterogeneity in plant vigor and ripening within a vineyard escorted by distinct soil compositions. Applying the right treatment can compensate for the delay in ripening and sugar accumulation in poor soils obtaining a more homogeneous grape composition and consequently better quality wines. Cluster and berry thinning demonstrate