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Aim. The aim of the work is to characterize the diversity of nut crops in terms of the efficiency of introduction in the conditions of the southern forest-steppe of Ukraine. Results and Discussion. In the collection of tree and shrub species of the State Dendrological Park "Ustymivskyi" numbering 472 species, nut crops are represented by more than 120 species. These include fruit species of temperate and subtropical zones from different botanical families. The climate in the area of the park is moderately continental with unstable humidity, frequent snowless winters with sharp fluctuations in air temperature. Dry winds are 2-3 times a year. The amount of precipitation is 254-777 mm per year. In the spring-summer period, there are periods without rain (up to two to three months). As a result of the study, the species and forms promising for introduction in such conditions have been identified. These are representatives of the genus Juglans: J. mandshurica Maxim. (Manchurian walnut), J. cinerea L. (gray walnut), J. nigra L. (black walnut) and J. regia L. (walnut). Corylus colurna (bear hazelnut) showed exceptionally good growth and abundant fruiting. However, in the last 10 years, the trees have become dry top and dry. Shrub species C. avellana (its forms 'Purpurea', 'Laciniata') and C. pontica C. Koch. turned out to be more adapted to climate change. The endemic steppe species Amygdalus nana L. (steppe almond) can be recommended in crosses when breeding for winter hardiness and an increased content of the alkaloid amygdalin (up to 4.5%). A. triloba Ricker. (almond three-bladed, regular and terry forms) is used as a decorative type. However, due to excessive disease damage (cercosporosis, orange spot, curly leaves, burns), plants lose their decorative effect. Repeated attempts to introduce into the collection such species as Carya alba (L.) C. Koch. (pignut hickory), Pterocarya pterocarpa (Michx.) Kunth ex Iljinsk. (caucasian wingnut), Fagus sylvatica L. (common beech) and Castanea sativa Mill. (sowing chestnut) were unsuccessful: the plants quickly died. Success has been achieved in the introduction and distribution of Xanthoceras sorbifolium and Ginkgo biloba in the forest-steppe and steppe zones. Conclusions. It is recommended to introduce walnut crops isolated as a result of the study into the range of plants used in landscaping, to create perennial plantations on lands unsuitable for agricultural production.

Aim. To determine the resistance of potato gene pool accessions to viruses in the southern forest-steppe of Ukraine and to select starting material for breeding. Results and Discussion. Our analysis of the climate changes for the period of 1955–2018 revealed that the unfavorable weather/climatic conditions during spring planting of tubers, as a result of which weakened plants were more easily depressed by viral infections, were the primary cause of potato cacogenesis in the southern forest-steppe of Ukraine. It was found that significant deviations from the multi-year average temperature and amount of precipitation contributed to the intense mass manifestation of symptoms of viral diseases or under favorable weather/climatic conditions, on the contrary, viral diseases were not visually detected. Studies have shown that the main factor in resistance to viral degeneration of potato varieties is the genotype, and its development and expression depend on growing conditions. It is also important to take into account emergence of new strains of viruses requiring continuous monitoring. Virus resistance of the varieties was visually determined. In order to identify viruses and study their morphology, electron microscopy, EIA and PCR were used. Conclusions. As a result of the study, sources of high field resistance to leaf-rolling, potato rugose and streak mosaics, which are valuable starting material for further practical use in breeding, as well as in scientific and educational programs, were identified.

Goal. To assess the diversity of collection material differing by eco-geographical origin for a set of economic and breeding parameters to select the most valuable accessions, to describe and evaluate them in order to form specific sets of gene pool accessions, to widely involve them in breeding both for traditional and for new purposes.Materials and Methods. The plant material was evaluated and described in compliance with "Expanded Harmonized Classifier of the genus Buckwheat (Fagopyrum Mill.)"," Classifier of the genus Fagopyrum Mill.", etc. Over 1,600 accessions have been investigated for the last 20 years. The information base of the study results contains data on 10-23parameters of accessions (yield, performance, plant architectonics elements, grain size, etc.).Result and Discussion. Based on the data, the collection gene pool was grouped by trait expression and expression of trait sets. Sources of some traits or of their combinations were offered to breeders: 29 accessions - of the grain number per plant (over 100 grains) and the node number in the stem branching point (up to 5); 49 accessions - of performance and inflorescence fertility; 110 accessions - of indices of individual seed productivity and grain number per plant; 27 accessions – of technological parameters of product (grain); 73 accessions - of even ripening; 22 accessions – of moderate shedding resistance, etc. The selected accessions are of different eco-geographical origin: from Ukraine, the Russian Federation, France, Georgia, Japan and Korea.Conclusions. The investigation of the collection material under contrast environmental conditions and selection of sources of economically and breeding-valuable characteristics makes the collection a valuable source of initial material for all breeding trends. Significant value of the collection accessions lies in their different eco-geographical origin, that is, in considerable diversity of gene complexes determining the expression level of a particular trait. Constant replenishment of the collection with new material from different parts of the world and generation of promising trends in the use of buckwheat products require constant search for new sources of valuable features, formation of trait and specific collections, trials and introduction of the gene pool in breeding and production.