The choice of rootstock is an important step related to the power of the grafted variety. Two table grape varieties were studied, namely Muscat Rusenski and Super Early Bolgar, grafted on two different rootstocks: SO4 (widely used in practice and accepted for the control) and Rupestris du Lot (of the common name Montikola). The study was performed in the experimental vineyards of the Institute of Agriculture and Seed Science Obraztsov chiflik, Rousse, in four replications with 11 plants in each. First class vines equalized in their vegetative developmentwere usedin the experiment. The values of fifteen agrobiological and growth traits were reported for the two vine varieties during vegetation. The obtained data were statistically analyzed using the evaluation criteria F-Fisher and t-Student. The results showed divergences in determining the existence of a substantial difference and its magnitude for the various traits using the Rupestris du Lot rootstock. Using Fisher's criteria 66.7% of the features were identified as significantly different in favour of the SO4 rootstockas compared with the control and based on the variability of traits. The highest degree of confidence was recorded for the influence 224 of the rootstock on the following traits: length of annual ripened growth shoot (a trait with the highest degree of variation), girth of the rootstock and weight of the annual ripened growth of one vine. Only 40% of the results showed significant differences in favour of the SO4 rootstock when using the Student criterion. When the averages of the surveyed traits were leveled, it was recommended to use comparison by variability for analysis and assessment and to apply the statistical criterion of Fisher. For both table grapes cv significant influence was observed when using the Montikola rootstock. For the Muscat Rusenski variety the effect was recorded for the growth traits, while for the Super Early Bolgar cv significant differences were reported for the productive traits. Therefore, the use of the Rupestris du Lot rootstock had a positive influence on the agrobiological traits of the studied grape varieties and respective yields of grapes from them.
Study on the influence of the Rupestris du lot rootstock on some agrobiological and growth traits of the Muscat rusenski and Super early bolgar table grape cultivars (Vitis Vinifera l.)