## 2 Materials and Methods  
### Field Measurements and Statistical Analysis  
The research was conducted from 2016 to 2020 at NOBILIS Vineyard (50\({}^{\circ}\)39 N; 21\({}^{\circ}\)34 E) in the Sandomierz Upland in southeastern Poland. The research material consisted of Regent variety vines, which were planted in spring 2010 at 2.0 \(\times\) 1.0 m spacing (5000 pcs \(\times\) ha\({}^{-1}\)) on lessive soil made from loess, which comprised 2.1% organic matter. The plants were managed as a single Guyot twine with a trunk height of 40 cm, a single bed of about 0.9 m length, and 1 two-eyed pivot. In the course of the experiment, regular protection against diseases, pests, and weeds was provided in accordance with the current vine protection 10 of 15 recommendations. The bushes were not irrigated, and soil pH ranged from 6.0 to 6.5, depending on the study year. In the bud-bursting phase, Hydrocomplex fertilizer (12N-11P-18K) was applied in the soil at a dose of 300 kg ha\({}^{-1}\), and other macro- and microelements were supplemented through foliar fertilization when needed.  
In the experiment, the effect of rootstock type on the quantity and quality of Regent grapevine yield was evaluated. The vines of the studied cultivars grew on 6 types of the following rootstocks: 101-14 Mgt, SORI, BB-49, 161-49 C, SO4, and 125 AA, the control were the bushes that were not grafted, growing on their own roots.  
The following parameters were analyzed: number and weight of grapes, number and weight of berries, and total Brix extract content (as arbitrary measurement of berries quality). Yield and number of grapes per bush were determined by counting and weighing berries from each bush with an accuracy of 0.001 kg. Average berry weight was determined by weighing and counting berries from five medium-sized clusters from each replicate. The fruit extract content was measured on the harvest day using a refractometer Abbe WAY 2W (EnviSense, Lublin, Poland) in juice squeezed from 100 representative berries collected from each combination. Alongside the plants parameters, the weather conditions were registered as they are very important factors influencing growth [43].  
Meteorological data was collected using the Pessl Instruments: iMETOS meteorological stations. The data recorder was located in Pechow, about 8 km from the place of research. iMETOS was powered by a battery and solar panel. The data recorder had a built-in UMTS/CDMA modern for direct communication with the FieldClimate platform. The system had internal memory and could store up to 8 MB of registered data (approx. 1 month). The data was regularly sent and stored on FieldClimate platform.  
The experiment was set up in a randomized block design, including 7 combinations with 5 repetitions. The repetitions were plots in which 3 plants were growing.  
After completion of the experiment, the obtained results were subjected to statistical analysis using one-way analysis of variance. Moreover, the obtained results were presented in graphical form. The inference was performed at the significance level of \(p<0.05\). Using Pearson correlation coefficients, correlations were established between individual measured parameters. In addition, multivariate data analysis techniques were performed using cluster analysis, the purpose of which was to group rootstock types into homogeneous groups, such that in one cluster the objects were more similar to each other than to the objects of other clusters. The results of the conducted analysis were presented by means of a dendrogram. All analyses performed were conducted using SAS Enterprise Guide 5.1 software.