The results of many years of research on propagation of promising forms of clonal stocks of apple trees of the Michurinsk State Agrarian University selection in the mother plantation by stooling, by herbaceous cuttings and by clonal micropropagation are presented. According to the complex of economic and biological features, promising clonal rootstocks of an apple tree with high shoot-forming capacity in the mother plant were identified: dwarf apple trees 2-3-49, 2-15-2, 2-15-15, 3-4-7, 5-21-27; semi dwarf apple trees 2-3-14, 2-9-49, 2-9-102, 2-12-10, 5-24-1, 5-27-1. The rootstocks that are promising for propagation by herbaceous cuttings – 2-3-14, 2-3-49, 2-12-10, 2-15-15, 3-4-7, 5-21-93; at the same time, treatment with exogenous promoters such as IBA and NAA at a concentration of 50 mg/l increases the yield and quality of stock material. A modified MSO nutrient medium with the addition of 0.5-1.0 mg/l of 6-BAP and 0.1-0.2 mg/l of IBA is selected for the clonal micropropagation of apple stocks.

This paper reveals main patterns of development of advanced clonal apple rootstocks of the Michurinsk State Agrarian University selection in the mother plantation. The studied growth and development indicators of shoots, as well as the level of their rooting in 40 genotypes, demonstrate significant heterogeneity of hybrid plants, which is due to their different genetic origin and the associated unequal growth force of parent shrubs. Correlations between the main quantitative morphological characters of parent shrubs of the studied genotypes were revealed. An interrelation of the height of the parent shrub and the area of its leaf surface is noted - on the expectation of 0.71 shoot; for the entire uterine shrub – of 0.45; between the output of standard layering from the shrub and the average rooting score (at 0.72). Promising clonal rootstocks with high yield indices in the mother plantation have been identified.

the dynamics of the chemical components content at plum fruits was studied for the growing seasons 2018-2021, significantly different in terms of average monthly temperatures and precipitation amounts. On average, during the study period, 10.8-16.2 % of soluble solids, 8.1-9.2 % of sugars, 1.5-3.4 % of titrated acids, -4.3-10.5 mg/100 g of vitamin C accumulated in fruits. the sugar-acid index varied from 4.1 to 4.4. In the studied plum cultivars during the research period, positive correlations of a high level were noted between the content of soluble solids and the amount of sugars in the fruit (at the level of 0.99), as well as between the content of vitamin C and titrated acidity (0.88). the positive effect of sufficient moisture on the level of accumulation of sugars, soluble solids and vitamin C in fruits was also recorded. A negative correlation was observed between the values of the average monthly summer temperatures and the vitamin C content.

The research was aimed at evaluating sweet cherry forms on a complex of economically valuable traits and the allocation of promising genotypes for further use in breeding and production. The forms of sweet cherries grow in Michurinsk city of Tambov region. The study of frost resistance was carried out in laboratory conditions. Annual branches were frosted for 12 hours at -32°C and -35°C. Reproductive buds in all studied forms were characterized by reversible damage (less than 3 points) at temperature regime -32°C and complete death at -35°C. 10-117 form was characterized by -35°C frost resistance in the middle of winter, in which the freezing degree of annual branches tissues and vegetative buds did not exceed 2 points. Over the years of research, elites 4/8-24, 10-115, 7-38, 10-117, 6-87, 4/9-15, 7-5 possessed resistance to moniliosis and coccomycosis (the damage degree not more than 2 points). The highest yield (9.75-9.84 t/ha) on average over three years was shown by forms 4/8-24, 7-38, 7-5. Yield at the control level was noted in forms 6-87, 4/9-15, 10-115. Elite forms 4/9-15, 7-38 were characterized by the largest mass of fruits, significantly exceeding the control variety. The average weight amounted to 7.3 and 7.2 g, and the maximum was 9.4 and 8.4 g respectively. Forms 4/8-24, 4/9-15, 7-38 combined the dessert taste of fruits (tasting assessment of 4.6-4.8 points), very juicy and dense pulp.

On the basis of integrated assessment, sweet cherry varieties Yantarnaya Savel’yeva, Mulatka and Lika, characterized by relative winter resistance, complex resistance to moniliosis and coccomicosis, were revealed. The given varieties are promising for commercial use in the southern part of the Central chernozem region. The degree of freezing of wood and vegetative buds after artificial freezing at –35 °C (II component) did not exceed 2.3 points and 1.6 points, respectively. In the field conditions, the degree of damage of these varieties to monilial burn was no more than 0.3 points, to coccomycosis it was 0.7 points, to monilial fruit rot it was 1.3 points. The yielding capacity of these varieties varied from 6.01 to 7.12 t/ha depending on the variety, which amounted to 123.7-146.5 % of the control. Variety were characterized by high commodity-consumer qualities of fruits. The average fruit weight was 5.1-7.1 g, and the overall taste evaluation was 4.6-4.8 points.