The article presents an analysis of many years of research (1928-2020) on apricot breeding and the development of its gene pool in the Nikitsky Botanical Gardens. The objects were the main indicators of world apricot production (crop yield, occupied area and dynamics of their changes), approaches to the development of the collection of this crop in Russia on the basis of the Nikitsky Botanical Gardens in the Crimea. For the analysis, we used the official data of the FAO, the materials of the website of the FSFI “Gossortkommission” - the State Register of breeding achievements approved for use and breeding research 1928-2020. We used generally accepted methods for variety study and breeding work, as well as techniques adopted in physiology and biotechnology. As a result, information is given about the spread of this crop in the world and in Russia, about industrial production and yield. The expediency of apricot cultivation in the southern regions of the Russian Federation is reflected. The prospects of the development of the gene pool of this valuable fruit crop in the conditions of the Crimea are shown. The results of the creation of competitive domestic apricot cultivars for the Crimea and southern regions of Russia are presented. Domestic apricot cultivars have been created, which are not inferior in their characteristics to foreign analogues, and in many respects surpasses them. The new cultivars are more adapted to the local conditions of cultivation and allow for high and regular yields, they represent a conveyor of fruits filling the market with fresh products in the period from mid-June to early August. The characteristics of new domestic cultivars created using the gene pool of the Nikitsky Botanical Gardens are given.

Peach is an important industrial stone fruit crop in the Crimea and southern Russia. In the Republic of the Crimea, it covers an area of 2,63 thousand hectares, which is 25,2% of the total area of fruit crops. Apricot plantations are located on an area of about 1000 hectares. A valuable economic feature of peach and apricot is the high content of biologically active substances in fruits that have a beneficial effect on human health. The objective of the research was to study the gene pool of the peach and apricot of the Nikita Botanical Gardens and the selection of forms and source cultivars with a high content of biologically active substances in the fruits for their inclusion in the breeding process. 60 forms of peach and 64 cultivars of apricot were studied by a complex of biochemical parameters. Apricot cultivars were divided into groups according to the amount of dry matter, sugars, ascorbic acid, titratable acids, leucoanthocyanins in the following combinations: according to two, three, four, five and six indicators, they are most pronounced. The group with two distinguished traits includes 13 (22,4%) cultivars (Ananasnyy Avgustovskiy, Alupkinskiy, Aresh Sanagyan, Aurel, Arzami Aromatnyy, Budapesht, Odissey, Zvezdnyy, Shedevr, Fiolent, Nagycorosy Orias, Shalard 2, Yarilo), with three - 10 (17,2%) varieties (Arzami Oranzhevyy, Iskorka Tavridy, Zvezdochet, Vozrozhdeniye, Senator, Naslazhdeniye, Krymskiy Medunets, Olimpri, Krymskiy Amur, Fregat), with four - one (1,7%) Samarityanin, with five two (3,4%): Zevs and Lyubimets Riсhtera. According to the complex high content of biological substances in peach fruits, 22 forms were selected. Most of them belonged to the Northern China ecological-geographic group (60,2%). The method of cluster analysis revealed the degree of similarity between the forms identified by the complex of biochemical characteristics and the best form based on the Euclidean distance.

In order to identify the features of the photosynthetic apparatus in a number of genotypes of the genus Ficus during the period of maximum probability of drought on the Southern Coast of the Crimea, studies were conducted on the concentration of chlorophylls and parameters of chlorophyll fluorescence induction (CFI) under controlled dehydration. The content of chlorophylls was determined by spectrophotometric method in leaves in a state of complete watering (control), after 2-3 hours of wilting, as well as after restoration of water availability. Changing the parameters of CFI was carried out using a chronofluorimeter "Floratest". The participation of chlorophylls in protective reactions under water stress is shown: in drought-resistant genotypes, with an increase in the level of water deficiency under conditions of various combinations of temperature and humidity, the content of chlorophylls "a" and "b" increases, decreasing after the stress effect is removed. It has been established that under hydrothermal stress, the stable ratio of chlorophyll "a" to chlorophyll "b" can be used as a biochemical parameter of drought resistance of genotypes of the genus Ficus . It was revealed that the reaction of the photosynthetic apparatus of deciduous species of the genus Ficus to dehydration under conditions of various combinations of temperature and humidity is species- and cultivar-specific: in the species F. virgata , an increase in the level of water deficiency causes changes in the functioning of the oxygen-releasing complex, and in weakly resistant cultivars of the species F. carica - a decrease in the efficiency of the light phase of photosynthesis and an increase in the thermal dissipation of excitation energy. As the stress state develops, the number of unrecoverable plastoquinones in the reaction centers of FS II increases. The high stability of the photosynthetic apparatus is characteristic of the varieties of the species F. carica - Sary Stambulsky and Sabrutsia Rozovaya.

During the summer seasons of 2020-2021, the drought resistance of 6 cultivars of Prunus armeniaca Lam. of various origin was studied on the basis of the collection plantings of the Nikitsky Botanical Gardens - the National Scientific Center. The results of the study of the parameters of the water regime of leaves, the quantitative content of photosynthetic pigments and phenolic compounds are presented. The assessment of the degree of potential ability of apricot cultivars to tolerate moisture deficiency during periods of maximum influence of arid factors of the summer season on the Southern Coast of the Crimea is given. It was found that the genotypes 'Nagycorosi Orias', 'Professor Smykov' and 'Kazachok' have a high adaptive ability to the action of hydrothermal stress. These cultivars are characterized by increased water-retaining forces of leaves and a high level of tissue repair, due to which they can carry out normal physiological and biochemical processes in conditions of soil and atmospheric drought. 'Khurmai' cultivar shows labile stability. 'Krymsky Amur' demonstrates the instability of the indicators of the water regime, and relatively weak resistance to high temperatures and lack of moisture during critical periods of vegetation. The maximum content of chlorophylls "a" and "b" was found in the leaves of 'Kazachok' and 'Nagycorosi Orias' cultivars, the minimum - in the leaves of 'Alupkinsky' cultivar. Under the prolonged influence of atmospheric and soil drought, the dependence of the accumulation of chlorophylls on the degree of resistance of each cultivar is manifested: a decrease in the content of photosynthetic pigments was observed, most pronounced in the drought-resistant cultivars 'Alupkinsky' and 'Krymsky Amur'. The cultivars relatively resistant to hydrothermal stress showed an increase in the concentration of phenolic substances by the end of the summer season, whereas the unstable cultivars either decreased or remained at the same level at the end of summer.

The article discusses the features and ways of resettlement of representatives of the genus Juniperus around the globe. It is shown that junipers are found in various natural zones and altitudinal belts of mountains in the vast territories of the Arctic and the tropical belt, hot arid low mountains and cold alpine meadows. Species of the genus Juniperus belong to different types of vegetation, from elfin to elements of dark and light coniferous forests and light forests. Representatives of the genus Juniperus successfully grow on dry gravel-stony steep slopes with thin soil, where the soil cover is often fragmented. Under severe edapho-orographic conditions, the competitive interaction of junipers with other plants is significantly reduced, which determines the formation of phytocenoses, in the structure of which they perform important anti-erosion and environment-forming functions.

One of the main reasons for the insufficient distribution of pear in areas and volumes of fruit production is the mismatch between the requirements of the crop and the possibilities of the growing environment in terms of soil and climatic conditions, especially in the winter-spring period. The objective of the research was to study perennial indicators of temperature stress during winter-spring periods and to identify genotypes with high resistance of generative and vegetative organs to low temperatures. The research was carried out in the conditions of the Crimean foothill zone on the base of collection and breeding plantations of the department "Crimean experimental station of horticulture" of FSFIS “NBG-NSC”. The analysis of meteorological indicators in winter and spring for the last 95 years (1926-2021) was carried out. It was revealed that in the Crimea during this period there were 24 winters with absolute minimum temperatures below -23°C, and the decrease of temperature to critical values in the spring period was observed with varying periodicity over 55 years. It has been noted that in the last years (1981-2021) the temperature stresses destructive for generative organs of pear trees during flowering tend to increase by 30%. As a result of research conducted over many years allocated pear cultivars with high resistance to temperature stresses of vegetative and generative organs, valuable for commercial cultivation and breeding process - Yakimovskaya, Mariya, Tavricheskaya, Tayushchaya, Nezabudka, Krymskaya Medovaya, Vitchiznyana, Dessertnaya, Rada, Bere Ardanpon, Daniela, Noyabrskaya, Oreanda Kryma, Diva, breeding forms - 59-72, 62-81, 62-90, 68-60, 107-18. Using correlation analysis, the magnitude and significance of the relationship between yield and climatic environmental factors for two pear cultivars were established.