Size and growth characteristics of young pear tree varieties in connection with selection for dwarfism

The aim of the study is to investigate the growth and crown structure characteristics of young pear trees for a comparative evaluation of varieties and their use as source material for breeding. The studies were conducted in a young pear orchard located in the northern part of the Yeisk District of the Krasnodar Region in 2021-2023. Year of planting: 2019; planting pattern: 3 × 5 m. Rootstock: Caucasian pear seedlings. The object of the study was 80 pear varieties of different ecological and geographical origins. Each variety was represented by three trees. The plot was not irrigated. The study was carried out in accordance with proven methods. The tree height, crown diameter in two directions, and trunk circumference length at a height of 70 cm were measured. The crown index, crown volume, and crown projection area were determined. The total growth over 3 years, average shoot length, and internode length were measured. The angle of branch divergence and the type of branching were assessed depending on the awakening of buds and the ability to form shoots. In the conditions of the Krasnodar Region, a comparative assessment of the growth characteristics and sizes of young pear trees of varieties of different origin was carried out for the first time, including the Skala and Obilnaya varieties - donors of dwarfism and dwarfism, with monogenic and polygenic control of growth force, respectively. The amplitude of variability of growth activity parameters of pear trees at a young age is shown. They are grouped by height. Different combinations of bud awakening and shoot-forming ability are established, which determines the features of branching and crown formation. Varieties with different expression of growth indicators are determined. As the initial material for selection, 20 pear genotypes with a complex of features characterizing intensive-type varieties and varieties with an angle of branching close to a right angle are selected. Promising for the selection of low-growing pear varieties with a branch inclination angle close to straight are Devo, Tavricheskaya, Tikhiy Don.