Photosynthetic activity in the leaf of ten grape varieties was studied in the conditions of the northern part of Forest-Steppe of Ukraine. From 2019 to 2020 meteorological data were recorded by the ‟Meteotrekˮ meteorological station. The influence of weather conditions of the spring-summer period at the beginning of the vegetation phases, which in 2019 took place on average 12 days earlier than in 2020, was noted. Analysis of changes in the induction of chlorophyll fluorescence (ICF) in leaves revealed the more efficient use of quantum energy of absorbed light by F0 in the leaves of most varieties was noted in the phase “the beginning of berry ripening”. During the three periods of the study, the varieties Aromatnyj, Zagadka, Ilichevskij rannij, and Kardishah showed a lower content of chlorophyll molecules, which do not have a functional connection with the reaction centers (RC). According to the Fp index the highest intensity of photosynthesis on average for all varieties was observed in the phase “the beginning of ovary growth”, the lowest – “the inflorescence is visible”. The potential productivity of grape plants determined by the ICF coefficient for all varieties was at a very high level and had a weak or moderate correlation with weather conditions during the growing season. The hydrothermal coefficient and Σ act t ≥10 °С had a weak effect on the efficiency of the light phase of photosynthesis (Ki) and a noticeable one (correlation coefficient r = 0.50 – 0.69) on the efficiency of dark photochemical processes (Rfd) in the leaves of most grape varieties.

Frost stress strongly affects the spatial distribution of plants. Among various weather hazards, frost causes the greatest economic losses in agriculture. Among various environmental hazards, it is frost that causes the greatest economic losses in agriculture. Although frost severely limits life forms and creates enormous economic losses, it has not been studied as thoroughly as other biotic or abiotic stresses. Frost resistance can be affected by many factors, including microclimate, soil condition, plant height, but they must be studied in a complex. The purpose of the research was to select frost-resistant cultivars and hybrids of the columnar apple tree under the conditions of the Forest Steppe of Ukraine. The research was carried out during 2021–2022 at the V.L. Symyrenko Department of Horticulture of the National University of Life and Environmental Sciences of Ukraine. The experimental basis for conducting research was the columnar apple tree plantations of the Training Laboratory «Fruit and Vegetable Garden». Frost resistance was determined during the period of deep rest by the method of direct freezing of one-year increments. Freezing was performed in the laboratory of plant physiology and microbiology of the National Academy of Sciences of Ukraine. In the researched plantations, when the test samples were frozen at temperatures of -25 and -30 °C during deep rest, different resistance of varieties and shoot parts to low temperatures was found. In all cultivars and hybrids of columnar type apple trees, the apical bud and generative buds were the most vulnerable, and the tissues of the middle and upper part of the shoot were the most resistant to frost. The damage index during general freezing was the lowest in the cultivars Valuta’, Sparta’, Favoryt’, Bilosnizhka’, as well as in the hybrids 9/110 Mykhailivske’, 11/15(2)’ and 9/78 Viktoriia’; it was the largest in the Bolero’ cultivars. Freezing of experimental samples at temperatures of -25 and -30 °C did not result in frostbite, critical for plants. All studied cultivars and hybrids of columnar apple trees are recommended for further research and production. The obtained results will be interesting for both experienced gardeners and amateur gardeners who plan to grow columnar apple trees in their garden.

AGROBIODIVERSITY f o r i m p r o v i n g n u t r i t i o n , h e a l t h a n d l i f e q u a l i t y 2019-57 -

The results of the study features of one-year sweet cherry trees formation on Cerasus mahaleb and VSL-2 rootstocks are given. Varietal rootstock combinations have been identified, which ensure the production of high-quality crowned one-year seedlings, suitable for creating modern industrial plantations. The research was conducted during 2018–2021 in the fruit nursery of the educational laboratory (EL) «Fruit and vegetable garden» of the Prof. V. L. Symyrenko Department of Horticulture NULES of Ukraine. As a result of the conducted research, it was established that the seed rootstock of the Cerasus mahaleb and clone VSL-2 have a high level of survival in the first field of the seedling nursery. It was found that in the studied varieties the rootstock VSL-2 provides a higher level of grafting and overwintering of inoculated eyes compared to the Cerasus mahaleb. Seedlings on VSL-2 rootstock have a larger number of side branches than Cerasus mahaleb. The variety Talisman’ is characterized by a high ability to branch in the nursery regardless of the rootstock. Seedlings, grafted on VSL-2, are distinguished by the total length and number of main roots. No visual and anatomical signs of incompatibility of components were found in the investigated variety-rootstock combinations at the stage of growing seedlings.

Growing high harvest of fruit in apple orchards is one of the priority tasks of gardeners in Ukraine. It is important to place the plantations in the most favorable zones for climatic conditions and in areas with appropriate soil conditions for certain apple varieties. This is achieved by introducing high-yielding, earlyfruiting, immune varieties with high fruit qualities, introducing appropriate rootstocks, especially weak and medium-sized, using optimal planting schemes, the correct methods of pruning trees. The aim is to study the productivity of new apple varieties in the Kyiv region. The research was performed during 2020-2021 at the Department of Horticulture prof. V.L. Symyrenko NULES of Ukraine. The experimental base for the research was apple orchards, which are located on the territory of the Training Laboratory "Fruit and Vegetable Garden" of NULES of Ukraine (Kyiv). The research site is located in the northern part of the Forest-Steppe of Ukraine. In the course of research conducted phenological observations, also, studied the morphological features of young plants, determined the assimilation surface area, counted the number of fruit formations, established the resistance of the studied varieties to the complex of pests and diseases, and determined the economic efficiency of growing new apple varieties in Kyiv region. The most intensive flowering took place in ‘Dmiana’ (9 points), while the other varieties - about (2-6 points). Flowering time was 7 (‘Palanka’, ‘Bahachka’) - 11 days (‘Dzhonahold’). Shoot duration - 67 (‘Palanka’) - 74 days (‘Hold Rash’, ‘Dzhuliia’, ‘Siabrina’, ‘Bahachka’, ‘Dmiana’). The number of fruits tied for the second year in the garden was the highest in the ‘Dmiana’ variety (average 20 pieces / tree). The results of research showed that most of the studied varieties were precocious. Most fruit formations were formed in the varieties ‘Siabrina’ (52 pieces), ‘Hold Rash’ (45 pieces), ‘Harant’ (43 pieces). According to the data obtained, it can be stated that in these varieties for the third year after planting there is an increase in productivity. The studied varieties for the 2nd year after planting have a height of 204 cm (‘Harant’) - 156 cm (‘Rozela’). There is a pattern: the small diameter of the trunk correlates with the small size of the tree itself in the varieties ‘Rubinola’, ‘Hold Rash’, ‘Dzhonahold’, and ‘Rozela’. Varieties with a large trunk circumference are characterized by significant tree growth (‘Berehynia’, ‘Palanka’, ‘Siabrina’, ‘Bahachka’). The exceptions are ‘Harant’ (tall trees with a fairly small trunk circumference) and ‘Dzhuliia’ and ‘Dmiana’ (large trunk circumference at low tree height). The largest leaf surface area was found in the varieties ‘Berehynia’ (1284.32 m2/ ha) and ‘Bahachka’ (1221.08 m2/ ha). ‘Hold Rash’ (218.88 m2/ ha), ‘Rubinola’ (412.0 m2/ ha) and ‘Dzhonahold’ (348.3 m2/ ha) were characterized by weak foliage. From the point of view of profitability it is expedient to grow all varieties. Varieties such as ‘Dmiana’, ‘Dzhuliia’, ‘Dzhonahold’ and ‘Palanka’ have the highest profitability rates (128 %), while ‘Rozela’ and ‘Rubinola’ have the lowest rates (63.6 %). Based on research, all varieties are recommended for cultivation in the Kiev region. Of particular note are the varieties ‘Dmiana’, ‘Dzhuliia’ and ‘Palanka’, which showed the best results in terms of productivity and resistance to a complex of diseases.