Determination of frost resistance of sweet cherry varieties using laboratory freezing

Abstract

The article presents the study results of the frost resistance of sweet cherry varieties of different ripening periods under artificial freezing. The damage degree of various tissues of one-and two-year-old wood, as well as fruit formations, was analyzed. In the group of early-ripening and late-ripening varieties, a significant resistance of the bark to the effect of low temperature was found, the average damage score was 0.7. Among late-ripening cherry varieties Drogana yellow had low-temperature damage to one-year-old wood, while no negative effect on the wood was observed for the Amazonka variety. The highest overall degree of freezing of one-year wood was observed for the varieties Mliivska yellow and Drogana yellow, the lowest values were obtained for the varieties Meotida, Mirage and Amazonka. Dispersion analysis based on a combination of factors confirmed the highest degree of wood freezing for the Mliivska yellow and Drogana yellow varieties. Among the early-ripening varieties, the two-year-old wood froze the most in trees of the Dar Mlieva variety, where the highest degree of damage to the tissues of the bark, cambium, and wood was observed. The least tissue damage was in the Mliivska yellow variety, however, its core had the maximum damage not only within the group, but also among all the studied varieties. By artificial freezing in laboratory conditions, it was established that the highest frost resistance of annual and perennial wood is characteristic of the early ripening variety Zoryana, medium ripening Meotida and late ripening Amazonka. As a result of laboratory freezing, the frost resistance of fruiting bodies did not exceed 2.2 points. The fruiting formations of the Drogana yellow exceeded all the studied varieties in terms of the level of damage. High resistance to low temperatures was shown by the fruiting formations of the varieties Zoryana, Mirage and, especially, Alyonushka. The damage level of other pomological varieties was in the range of 1.9-2.25 points. The most negative effect of low temperatures was caused on flower germs.