IMPROVING THE METHOD OF NUT CROPS DIRECT FREEZING TAKING INTO ACCOUNT THE CHANGING CLIMATIC CONDITIONS

The paper presents the analysis on the weather conditions for the winter periods 2005–2022 in the central part of the Republic of Belarus. Climate change towards warming has led to the fact that over 18 years of observations, the negative impact of frequent and prolonged thaws on the development of frost resistance has increased. The shift of the calendar dates of the minimum temperature drop in winter to February and the need to assess the ability of hardening to a rapid frost increase after a thaw were recorded. The frequent alternation of long periods with an average daily temperature above 0 o C and frosty days in the second half of winter provokes earlier dates for plants to emerge from a state of forced rest. To assess the potential for four components of winter hardiness in laboratory conditions, based on the generalization of meteorological data for 18 years, freezing regimes were developed for the central zone of Belarus. The effectiveness of the proposed regimes was evaluated on cultivars of various geographical origin with a known level of field hardiness after the harsh winter of 2020–2021: 3 cultivars of hazelnuts ‘Tambovsky ranny’ (hardy), ‘Catalonsky’ (medium hardy), ‘Red Lambert’ (weakly hardy) and 4 walnut cultivars of Russian selection: ‘Pinsky’ (medium hardy), ‘Pamyat Minova’, ‘Samokhvalovichsky-1’, ‘Samokhvalovichsky-2’ (hardy). For hazelnuts, the main components of winter hardiness are: resistance to a decrease in air temperature to –30 o C in the middle of winter (component II) and resistance to a rapid increase in frost (to –30 o C) after thaws in February (component III); for walnuts, the limiting factor is resistance to a decrease in air temperature to –30 o C in the middle winters (II component). The results obtained are consistent with field observations. The proposed freezing conditions under simulated conditions make it possible to assess the winter hardiness potential of hazelnut and walnut cultivars and identify new adaptive genotypes for cultivation in gardens and use in breeding work.