FROST RESISTANCE OF THE COLUMNAR APPLE TREE THE METHOD OF DIRECT FREEZING

Abstract

Frost stress strongly affects the spatial distribution of plants. Among various weather hazards, frost causes the greatest economic losses in agriculture. Among various environmental hazards, it is frost that causes the greatest economic losses in agriculture. Although frost severely limits life forms and creates enormous economic losses, it has not been studied as thoroughly as other biotic or abiotic stresses. Frost resistance can be affected by many factors, including microclimate, soil condition, plant height, but they must be studied in a complex. The purpose of the research was to select frost-resistant cultivars and hybrids of the columnar apple tree under the conditions of the Forest Steppe of Ukraine. The research was carried out during 2021–2022 at the V.L. Symyrenko Department of Horticulture of the National University of Life and Environmental Sciences of Ukraine. The experimental basis for conducting research was the columnar apple tree plantations of the Training Laboratory «Fruit and Vegetable Garden». Frost resistance was determined during the period of deep rest by the method of direct freezing of one-year increments. Freezing was performed in the laboratory of plant physiology and microbiology of the National Academy of Sciences of Ukraine. In the researched plantations, when the test samples were frozen at temperatures of -25 and -30 °C during deep rest, different resistance of varieties and shoot parts to low temperatures was found. In all cultivars and hybrids of columnar type apple trees, the apical bud and generative buds were the most vulnerable, and the tissues of the middle and upper part of the shoot were the most resistant to frost. The damage index during general freezing was the lowest in the cultivars Valuta’, Sparta’, Favoryt’, Bilosnizhka’, as well as in the hybrids 9/110 Mykhailivske’, 11/15(2)’ and 9/78 Viktoriia’; it was the largest in the Bolero’ cultivars. Freezing of experimental samples at temperatures of -25 and -30 °C did not result in frostbite, critical for plants. All studied cultivars and hybrids of columnar apple trees are recommended for further research and production. The obtained results will be interesting for both experienced gardeners and amateur gardeners who plan to grow columnar apple trees in their garden.