PEAR (PYRUS COMMUNIS L.) GENOTYPES AND THEIR HYBRIDS EVALUATION FOR WINTER HARDINESS IN THE CENTRAL REGION OF RUSSIA

This study comprises the selection of winter-hardy to highly winter-hardy pear (Pyrus Communis L.) hybrid seedlings procured from various genetic origins. The development of pear hybrids resulted from intraspecific, interspecific, and distant hybridization. The simulation of the most damaging factors in the artificial climate chamber ensued according to the second and third components of winter hardiness - maximum frost resistance in a hardened state and stability of resistance to frost during the thaw. Critical temperatures affected the same seedlings, successively applying the specified modes, i.e., hardening at -10°C, freezing at -37°C (12 h), hardening at -10°C, thaw at +2°C (5 days), and freezing at -25°C (12 h). Combining genetically related variants to the highly winter-resistant cultivar, Phorun established the high breeding value for the yield of hybrid seedlings resistant to frost on the 2 + 3 components of winter hardiness. Thus, in the family 17-43-30 (Phorun - free pollination) × Shihan, 5.0% of transgressive genotypes came up, which withstood the given modes without damage to the buds and central tissues, showing 48.3% of highly winter-resistant forms. In a hybrid combination of 24-45-45 (Phorun × Olivier de Serre) × (Gervais + Olivier de Serre + Dekanka Zimnyaya), 33.3% of seedlings with frost resistance at the level of the highly winter-resistant control cultivar Tonkovetka attained selection. Remote hybridization opens up new opportunities in the pears’ selection for frost resistance. In total, and as a result of distant hybridization, 5.47% of the genotypes (with frost resistance for the 2 + 3 components of winter hardiness above Tonkovetka), 18.24% (at the level of Tonkovetka with freezing to 1.0 point), and 20.73% types (at the level of winter-resistant control cultivar Bessemyanka with freezing to 2.0 points) gained distinction.