In 2019, the Operational Group carried out a first evaluation of the vegetative and productive performance of the resistant hybrids in the collection at the experimental vineyard of Vicobarone. Although the vineyard has the typical traits of a planting in the first year of production (low shoots growth, limited berry growth and reduced cluster size), the measurements made can offer a useful preliminary picture of the aptitude of the various genotypes under test for cultivation in the Colli Piacentini area.
All the vines in the collection showed an excellent average bud fertility of more than 1.5 inflorescences per bud. Soreli (cross Friulano x 20-3) resulted the most productive white variety (3.18 kg/vine) and UD 31-103 (cross Merlot x 20-3) showed the highest production level among the red varieties (2.13 kg/vine). These production levels are the result of a high number of clusters per vine combined with a small size of clusters (31 clusters/vine per 104 g average cluster weight for Soreli, and 35 clusters/vine per 61 g average cluster weight for UD 31-103). The less productive varieties (UD 72-096 and Merlot Khorus with 1.28 kg/vine) also showed a high number of clusters per vine (never less than 22), but with little berry growth. This suggests that, once the vineyard has reached full maturity, all the vines under test could reach high production levels.
The course of maturation of the resistant vines was much earlier than that of the most common autochthonous vine varieties in the Colli Piacentini area. On 19 August, all the white grapes had a titratable acidity level of less than 5 g/L and a concentration in soluble solids of more than 20 ° Brix. The only exception was Sauvignon Rytos (Sauvignon blanc x Bianca cross), which showed a significantly delayed ripening process compared to the other vines in the collection (acidity of more than 6 g/L until September 2), but in any case earlier compared to other white varieties commonly used in the territory (Fig. 1). The red varieties also showed a high level of ripeness. The concentration of soluble solids in all the varieties under test was already above 22° Brix from 19 August, with the only exception of Cabernet Eidos (Cabernet Sauvignon x Bianca cross), which was slightly later than the others (Fig. 2).
Fig. 1. Evolution of titratable acidity in the grapes of resistant hybrids in the collection and in Ortrugo and Sauvignon blanc grapes cultivated in neighbouring vineyards in 2019.
Fig. 2. Evolution of the concentration of soluble solids in the grapes of the resistant hybrids in the collection and in the grapes of Ervi and Barbera cultivated in a neighbouring vineyard in 2019.
Although the maturation of resistant hybrids will have to be re-evaluated when the vineyard reaches full vegetative and productive maturity, the first data collected in 2019 suggest that among the white grapes under test Sauvignon Rytos (Fig. 3) is the one that could be more interesting in the Colli Piacentini area, due to its good production potential and the dynamic of ripening of the grapes.
Fig. 3. A ripened cluster of Sauvignon Rytos