The level of winter hardiness of red raspberry collection specimens under the conditions of the Orel region

The aim of the research is to identify promising varieties of red raspberry of different ecological and geographical origin by winter-hardiness in the conditions of the Orel region. To achieve the goal, we conducted a field assessment of the degree of winter damage of red raspberry varieties in different winter weather conditions. The studies were conducted at the All-Russian Research Institute for the Selection of Fruit Crops in 2019-2021 on a variety stock of red raspberry. The objects of research were 18 varieties of raspberry. The place of research was a collection plot of red raspberry, planted in spring of 2017 on the scheme of 4,0х0,5m. The field record keeping of frost was conducted by estimation method at the beginning of the flowering period of plants and expressed in points. During the study period climatic conditions of 2019-2021 were characterized by a large contrast of air temperature and availability of precipitation. In winter 2018/2019, the average degree of frost in the field conditions ranged from 1.3-1.9 points. In winter of 2019/2020 there were less lesions of varieties, which is due to the warmer autumn-winter period. The damage ranged from 1.0-1.7 points, the minimum index was noted in the variety Volnitsa. The maximum damage was detected in the winter period 2020/2021. The air temperature in January dropped to -35°C and was at -30 ... -32°C for a long period, which negatively affected a number of European and American raspberry varieties, such as Glen Ampel, Glen Magma, Oktavia, Cascad Delait, Lyachka. The degree of shoot damage was noted in the range of 2.5-2.7 points. However, during the growing season the damage of shoots recovered, and the plants gave a reserve yield of fruits. The minimum shoot wood damage was found in Joan J., Glen Lion, and Bright (1.3-1.5 points). On average, domestic varieties Volnitsa, Sputnitsa, Peresvet, Bright and Early Dawn were characterized by maximum winter hardiness for three years; Glen Lion and Joan J. were of foreign varieties. The degree of frost penetration of wood was 1,2-1,5 points.