## 3 Results and Discussion
### Summary of 5-Year Observation
The positive influence of rootstocks on yield, vine vigor, and longevity in comparison with own-rooted plants was shown by [35] by evaluating 14 rootstocks and 12 grapevine cultivars. A different relationship was shown by [38] by evaluating the effect of 1103 P, SO4, Dog Ridge rootstocks, and own-rooted vines on the yield of Thompson Seedless, Flame Seedless, and Kishmish cultivars, finding that regardless of cultivar, own-rooted vines yielded better than those grafted on SO4 rootstock. Among the grafted shrubs, shrubs on SO4 yielded the least, while those on Dog Ridge yielded the best. Ref. [36] showed that the yields of all grafted vine varieties evaluated in his study were significantly higher than those of varieties on their own roots, with special attention paid to the rootstocks: Ramsey and Dog Ridge. Similarly, ref. [27] showed higher productivity of grafted Cabernet Fran and White Riesling varieties than own-root varieties. Ref. [28] showed that Gruner Veltliner vines grafted on SO4, K5 BB, and 5C rootstocks had higher growth vigor and wood production (green matter) than vines on their own roots. Ref. [33] showed no differences in yield, fruit composition, and green matter removed between shrubs on rootstocks and on own roots in the Gewurztraminer cultivar. Ref. [37] showed that Erbalance shrubs grafted on 101-14, 420 A, Rupestris du Lot, K5 BB, and SO4 were characterized by lower viability than on their own roots. Additional analysis of selected parameters, i.e., fruit extract (Figure 1), total yield (Figure 2), and berry weight (Figure 3), for two extreme years of the study was conducted. Three distinct clusters were observed in fruit extract in both years. Cluster one in both analyzed vintages is SO4 rootstock, similarly shaped to cluster three, which consists of 125 AA and 101-14 Mgt rootstocks. Cluster two in both vintages is the largest and is divided into two subgroups. In 2018, one subgroup was 5 BB and the SORI and own-root rootstocks, while the outlier was 161-49C. In 2020, two subgroups were separated, the first being SORI and 5 BB rootstocks, and the second being own root and 161-49C. Two distinct clusters were observed in total yield in both years. In 2018, the first cluster consists of own root and rootstock 125 AA and outlier SO4. The second cluster consists of two subgroups, the first being SORI and 5 BB rootstocks, and the second being 161-49C and 101-14 Mgt. The year 2020 shows a similar split between the two clusters and subgroups. The first cluster consists of pads 161-49C and 125 AA and outlier SO4. The second cluster consists of two subgroups, the first being similarities between own root and rootstock 5 BB, and the second being SORI and 101-14 Mgt. Three distinct clusters were observed in berry weights in both years analyzed. The third cluster in both years consists of SORI and 101-14 Mgt rootstocks. In 2018, cluster one consisted of own root and rootstock 125 AA, while cluster two consisted of SO4 and 5 BB, showing the least similarity to 161-49C. In 2020, the first cluster consisted of the 125 AA rootstock, which was also the outlier, and the other types analyzed. The second-largest cluster consisted of two subgroups, the first being own root and rootstock 5 BB, while the second subgroup consisted of SO4 and 161-49C. Figure 1: Cluster analysis of Regent grape fruit extract considered in the extreme years of the study. Figure 3: Cluster analysis of Regent grape berry weight considered in the extreme years of the study. Figure 2: Cluster analysis of Regent grapevine total yield considered in the extreme years of the study. Pearson correlation analysis showed significant correlations between the assessed parameters of yield quantity and quality of Regent grapevine (Table 3). A significant correlation was found between berry weight and the number of clusters per bush, the number of berries per cluster, and the extract.