Exploring the opportunity of selective harvesting in a ‘Barbera’ vineyard from Colli Piacentini

Precision viticulture allows identifying vineyard zones of similar performance and select fruit at harvest to enhance the overall quality. If selective harvesting (SH) does not exclude handpicking operations, it is undoubtedly more feasible on larger scale when performed mechanically. Although SH profitability has been already demonstrated in extensive viticulture, little information is available within the Italian context that covers small vineyards often featuring large orographic variability, soil heterogeneity and varietal diversity. Based on a pre-trial remotely-sensed vigor map (5 m resolution), the study was performed in a mature 1.5 ha Vitis vinifera L. 'Barbera' vineyard located in the Colli Piacentini wine district. NDVI values allowed identifying three vigor classes (LV = low, MV = medium and HV = high) with ground-truthing being performed over three years. Vine growth, yield, leaf nutritional status and fruit composition were measured while soil properties were also assessed in parallel. Experimental wines were made in triplicate and sensory analysis was performed by comparing vigor classes; an additional sample was made by mixing wines in different proportions according to yield per hectare to simulate traditional harvest. Results showed that HV was associated to heavier soils with higher fertility and water holding capacity, leading to higher leaf area (3.99 vs. 2.67 m2 vine‑1 recorded in LV), excessive crop load (6.99 vs. 3.37 kg vine‑1) and incomplete or delayed ripening (TSS: 20.7 vs. 24.9 °Brix; TA: 9.72 vs. 7.71 g L‑1; anthocyanins: 0.82 vs. 1.60 g kg‑1). LV wines were more colored with higher purple hues compared to HV; LV wines were also fuller body, more balanced and, occasionally, even more astringent than HV. SH can boost exploitation of vineyard variability in the Colli Piacentini area and grapes from the same parcel, used for producing young sparkling and barrel-aged still wines. Seasonal feasibility and economic convenience of SH need to be demonstrated.