The genetic makeup of each scion–rootstock combination, along with their physiological and biochemical interactions with the environment, is unique. This necessitates a continuous process of research and the collection of extensive information about their behavior. To address this, the influence of the less well-known rootstock Supporter 4 Pi 80 and the widely used M9 T-337 on the growth and reproductive characteristics of the Granny Smith apple cultivar was studied. The trees were planted in the autumn of 2017 at a density of 2,380 plants per hectare. They were branched in the nursery (7+), and no pruning was applied after planting. During the period 2019–2022, the rootstocks Supporter 4 Pi 80 and M9 T-337 showed significant differences in terms of tree height, but not in the volume of the crowns they induced in the tested cultivar. Both rootstocks did not differ significantly in terms of yield per unit area and crop efficiency coefficients with this cultivar. The Granny Smith cultivar produced greater fruit weight when budded on M9 T-337 compared to Supporter 4 Pi 80. Keywords: rootstocks, cultivars, growth, yield, productivity
Tabakov et al. (Tue,) studied this question.