SELECTION OF ROOTSTOCKS IN CREATION OF MOTHER-CUTTINGS PLANTS OF APPLE TREE OF THE «BASIC» CATEGORY

The increase in high-temperature stress in recent years during the summer growing season complicates the realization of the production potential of the apple tree. Therefore, it is very relevant to use scion-rootstock combinations based on rootstocks with high drought resistance in creation mother-cutting orchards of apple trees in the “Basic” category. In the conditions of Krasnodar, the summer months of 2018-2023 became hotter, which is confirmed by data on the excess of the average monthly temperature over long-term values. July was the hottest in 2018, 2020 and 2021. (38.0, 38.0 and 36.3 ºC, respectively). In August, the excess of the long-term norm was greatest in 2018, 2021 and 2023. The trend of increasing temperatures in the autumn months has led to a lengthening of the growing season and a decrease in the resistance of apple plants to unfavorable overwintering conditions, which can negatively affect the quality of cuttings. The purpose of the research was to identify the most adaptive apple tree rootstocks for use in mother-cutting plantings of the «Basic» category. We assessed the drought resistance of the most common introduced apple rootstocks M 9, MM-106 and the rootstock breed by FSBSI NCFSCHVW SK 2U under conditions of high-temperature stress during the summer growing season. Leaf water content in particularly hot years (2020, 2021, 2023) was predominantly higher in the M 9 and SK 2U rootstocks. The best water-holding capacity of leaves was observed in the rootstocks M 9 and SK 2U, the worst – in the rootstock MM-106. Preference should be given to the semi-dwarf rootstock SK 2U when designing mother-cutting apple tree plantings of the “Basic” category. SK 2u will be able to maintain the intensity of growth processes and ensure the production of cuttings of a standard size and the required quality in greater quantities under conditions of summer high-temperature stress than mother trees on a dwarf rootstock M 9 with a smaller crown volume than on SK 2U.