Study of frost resistance of generative buds of scion/ rootstock combinations of sweet cherry by freezing in controlled conditions

The paper presents the results of two-year research on frost resistance study in 18 scion/rootstock combinations of sweet cherry: Fatezh and Chermashnaya varieties grafted on 9 rootstocks (Izmailovsky, AVCH-2, V-5-88, VC-13, Moskoviya, VSL-2, Stepnoy Rodnik, Colt and seedling rootstock Prunus magaleb L.). The research was carried out in 2019-2020 in the laboratory of physiology and biochemistry of FSBSI «Federal Horticultural Research Center for Breeding, Agrotechnology and Nursery» by artificial freezing method in the climate chamber TH-6 JEIO TECH -1000. It was established that after freezing at t = - 29ºC, the floral rudiments' preservation in the Fatezh variety was more than 80%, and in the Chermashnaya variety — about 40%. Limits of frost resistance change of varieties' reproductive buds depending on the rootstock were shown: Fatezh variety — from 62.2% (VSL-2) to 81.7% (Izmailovsky), and Chermashnaya variety — from 25.5% (P. magaleb L) to 65% (Izmailovsky). When using Izmailovsky and AVCH-2 clone rootstock, the preservation of flower rudiments increased by 15 -20% compared to P. magaleb L. The most frost-resistant scion/rootstock combinations were revealed: Fatezh/Izmailovsky and Fatezh/AVCH-2, which preserved more than 87% of live rudiments. A positive correlation between floral buds' frost resistance and chlorogenic acid content has been established.