## 3 Results
### Vessel Density and Number of Vessels per Diameter  
The density and frequency of xylem vessel size classes differed according to the cultivar. Vessel density was quantified as the average number of vessels per 1 mm\({}^{2}\). Red-berried cultivars--The 'Montepulciano' cultivar showed the highest value for vessel density (60.0 vessels mm\({}^{-2}\)), while 'Aleatico 83/c2' showed the lowest value (28.7 vessels mm\({}^{-2}\)). In the other cultivars, intermediate values were found, with high variability among the cultivars (Figure 6). For the vessel size frequency, in the red-berried cultivars, the most representative diameter classes were 60-79 \(\upmu\)m and 80-99 \(\upmu\)m. However, some cultivars showed the highest diameter classes, such as 'Sangiovese' SG11 (7.3 vessels), 'Trebbiano roso' TR71 (6.2 vessels), 'Limberger' (4.6 vessels) and 'Syrah' (5.8 vessels), where the vessels were included in the 100-119 \(\upmu\)m class, and 'Pinot nero' (5.2 vessels) and 'Nebbiolo' (6.8 vessels), where the vessels were included in the \(>\)200 \(\upmu\)m class. Other cultivars showed lower diameter classes, such as 'Montepulciano' (7.8 vessels), 'Cabernet Sauvignon' (6.3 vessels), 'Pinotage' (5.2 vessels) and 'Egidiola' (8.2 vessels), which showed vessels in the 40-59 \(\upmu\)m class (Figure 6). Figure 5: Box plot representing means of equivalent circle diameters measured in the 27 white-berried grapevine cultivars. The median and mean are represented by solid red and dotted pink lines, respectively. Top and bottom lines of the box correspond to the 25 th and 75 th percentiles of the data, respectively. Error bars represent the 10 th and 90 th percentiles. Circles represent outliers. Different letters above columns indicate significant differences between cultivars ([PERSON]’s tests; \(p\leq 0.05\)). The geographic origin from Vitis International Variety Catalogue database (www.vivc.de) [(39)] was added. White-berried cultivars--In this group of cultivars, the highest vessel density was observed in 'Garofonata' (46.7 vessels mm\({}^{-2}\)), followed by 'Chiapparu' (43.0 vessels mm\({}^{-2}\)), while the lowest was observed for 'Sauvignon Blanc' R2 (18.3 vessels mm\({}^{-2}\)). All of the other cultivars had intermediate values (Figure 7). For the vessel size distribution, the most representative classes for most of the cultivars ranged from 80-99 \(\upmu\)m to 100-119 \(\upmu\)m. However, except for 'Garofanata' with 10.3 vessels  
Figure 6: Quantification of vessel density and distribution per diameter class (vessels/mm\({}^{2}\)) for the 24 red-berried grapevine cultivars. The differentiation in colour defines the minimum (light green) to maximum (light red) values. Different letters above columns indicate significant differences between cultivars (Fisher tests; \(p\leq 0.05\)). *, esca incidence. Figure 7: Quantification of vessel density and distribution per diameter class (vessels/mm\({}^{2}\)) for the 27 white-berried grapevine cultivars. The differentiation in colour defines the minimum (light green) to maximum (light red) values. Different letters above columns indicate significant differences between cultivars (Fisher tests; \(p\leq 0.05\)). *, esca incidence. in the 60-79 \(\upmu\)m class, a number of cultivars showed greater vessel sizes corresponding to different classes. In detail, some cultivars showed vessel sizes corresponding to the 120-139 \(\upmu\)m class, such as 'Sauvignon Blanc' R2 (5.4 vessels), 'Viogner' (5.6 vessels), 'Trebbiano' SC TR12 (10.3 vessels) and 'Verdicchio' SC VE23 (7.8 vessels). Other cultivars showed vessel sizes that corresponded to the 140-159 \(\upmu\)m class, such as 'Sauvignon Blanc' R2 (5.4 vessels), 'Roussanne' (9.0 vessels) and 'Grechetto' T (6.2 vessels). In the 160-179 \(\upmu\)m class, there were 'Viogner' (5.6 vessels) and 'Falanghina' (5.2 vessels). Finally, in the \(>\)200 \(\upmu\)m class, 'Sauvignon Blanc R2' (5.4 vessels) and 'Greco' (8.3 vessels) were observed (Figure 7).