The new association Rhamno emeretinae–Pinetum sylvestris ass. nov. representing the unique type of sub-Mediterranean forests with participation of Caucasian endemic species was described in the northern part of Abkhazia (the Western Caucasus). Small areas of these pine dwarf-shrub - grass drought-resistant petrophylous forests surrounded by zonal broad-leaved vegetation rarely found on the steep (45-60°) south-, south-east and east-faced limestone mountain slopes of the eastern part of the Gagrskiy Ridge at altitudes of 550-600 m. The peculiarity of the floristic composition of the association is determined by the combination of meso-xerophilous petrophilous species (Argyrolobium biebersteinii, Brachypodium rupestre, Campanula alliariifolia, Carex humilis, Teucrium chamaedrys) and mesophytes occurring at the upper part of the forest belt and in subalpine belt (Daphne pseudosericea, Melampyrum elatius, Salix caucasica, Valeriana alliariifolia). The association Rhamno emeretinae–Pinetum sylvestris was included in the class Erico-Pinetea Horvat 1959, however, its position in the orders and alliances system remains open. This association together with the Arctostaphylo caucasicae–Pinetum sylvestris Ermakov et al. 2018 occurring on calcareous bedrocks represent rare extra-zonal forest types existing because to the peculiar microclimate of the Bzyb Canyon and they are preserved in the Ritsinskiy Relic National Park (Abkhazia Republic). 

The classification of subalpine shrub (Alnus alnobetula subsp. fruticosa) communities of north-eastern  part of the Altai-Sayanian mountain region was conducted. The association Calamagrostio obtusatae–Alnetum  alnobetulae ass. nov. was described. It was demonstrated that all existing Altai-Sayanian associations of  subalpine Alnus alnobetula shrub communities should be included in the class Betulo carpaticae–Alnetea viridis  Rejmanek ex Boeuf et al. 2014 and order Doronico altaicae–Alnetalia alnobetulae ord. nov. The floristic  peculiarity of the new order is determined by North-Asian and Altai-Sayanian subalpine and subalpine-forest  species: Alnus alnobetula subsp. fruticosa, Allium microdictyon, Aquilegia glandulosa, Anthoxanthum  nipponicum, Bergenia crassifolia, Betula glandulosa, Bistorta officinalis subsp. officinalis, Carex aterrima,  Doronicum altaicum, Euphorbia pilosa, Lonicera altaica, Micranthes nelsoniana subsp. aestivalis, Pedicularis  incarnata, Poa sibirica, Rhododendron aureum, Saussurea latifolia, Solidago dahurica,Viola altaica. The  associations Athyrio distentifoliae–Duschekietum fruticosae Zibzeev et Nedovesova 2017, Bergenio crassifoli–  Duschekietum fruticosae Zibzeev et Nedovesova 2017, Carici iljinii–Duschekietum fruticosae Zibzeev et  Nedovesova 2017, Calamagrostio obtusatae–Alnetum alnobetulae ass. nov. and community Duschekia fruticosa  were included in the alliance Aquilegio glandulosae–Alnion alnobetulae all. nov. The association Doronico  altaici–Duschekietum fruticosae Lashchinskiy 2015 was included in the alliance Athyrio filicis-feminae–Alnion  alnobetulae all. prov. The high floristic peculiarity of the higher units was supported by results of DCA  ordination. 

The objective of the study is to establish the features of the spatial-biotopic distribution of species composition and taxonomic groups of Greek juniper light forests of Crimea in order to clarify the degree and pattern of differentiation of these communities. Depending on the peculiarities of the species composition, location and type of underlying rock, the array of juniper woodlands was preliminarily divided into three groups (Baydarsko-Balaclavskaya, Western-South Coast, Eastern-South Coast) and six subgroups (Baydarskaya, Balaclavskaya, Western-South-Coast carbonate, Western-South-Coast non-carbonate, Eastern-South-Coast carbonate, Eastern-South-Coast non-carbonate). Separately, groups of the open forests were analyzed, identified by edaphic characteristics – those growing on limestone and those growing on non-carbonate rocks. In the course of research, the list of vascular plants of Greek juniper light forests of Crimea was clarified and supplemented. It currently includes 585 species and subspecies from 292 genera of 67 families. The species composition was determined, the systematic structure of coenofloras of the groups and subgroups was analyzed, they were compared in absolute and relative indices, and the specific species to each coenoflora were determined. This made it possible to identify the features of the species composition and structure of studied coenofloras depending on spatial and edaphic factors. Based on the floristic criterion, the boundaries between separate groups and subgroups of woodlands were clarified, and a map of their location was compiled. It has been established that the Western-South Coast group and the Western-South-Coast carbonate subgroup of juniper light forests are distinguished by the greatest floristic richness and specificity of the flora. It is concluded that it is advisable to consider the light forests of the Baydarskaya Valley and those of the environs of Balaclava as separate groups.

The results of the research on the water regime, redox enzymes activity, proline concentration and the state of the photosynthetic apparatus parameters in apricot cultivars in the connection with their drought resistance are presented. It has been revealed that the cultivars Nagycorosi Orias and Kazachok demonstrated a high degree of drought resistance. The cultivar “Krymsky Amur” was characterized by consistently low drought resistance. In all the studied cultivars, an increase in the proline concentration in leaves was observed during the wilting process, and a decrease was noted when the water supply was restored. Changes in polyphenoloxidase activity were cultivar-specific. During the period of maximum probability of drought on the Southern Coast of the Crimea (July-August), under the dehydration process, peroxidase activity increased in resistant cultivars, while in the low resistant cultivar “Kazachok” and the cultivar with labile resistance “Khurmai” it decreased.

It was found out that the development of water deficiency was the cause of a reversible decrease in the maximum and variable fluorescence in the cultivars “Khurmai” and “Nagycorosi Orias”. In the cultivar with low resistance, irreversible inactivation of photosynthesis was recorded during the restoration of turgidity. It was concluded that it is possible to use the chlorophyll fluorescence induction (CFI) method for objective diagnostics of apricot plants' drought resistance under the conditions of the Southern Coast of the Crimea.

Currently, the use of nanoparticles (NPs) has demonstrated their positive effects on explant sterilization, micropropagation, callus induction, organogenesis, somatic embryogenesis, genetic transformation and production of secondary metabolites. The aim of this work was to study the effect of nanoparticles of selenium (Se), silicon oxide (SiO₂) and tricalcium phosphate (Ca₃(PO₄)₂) on the growth and development in vitro of Chrysanthemum × morifolium Ramat.; Ficus carica L.; Fragaria × ananassa Dushesne; Lamium glaberrimum (K. Koch) Taliev and Rosa L. microshoots. Explants were cultivated on Murashige and Skoog (MS) medium supplemented with various concentrations of NPs. An ambiguous effect of NPs on morphogenesis in vitro was revealed depending on the genotype of the crop being studied and the type and concentration of NPs used. It was found that Se NPs had a positive effect on the growth of microshoots and the formation of leaves of chrysanthemum, fig and Lamium glaberrimum. Analysis of the chlorophyll a and b content in the leaves of plants cultivated on media with Se NPs did not show a significant discrepancy between the control and experimental treatments. The exception was strawberry and rose microshoots: a concentration of 0.5 mg/l Se NPs in the nutrient medium caused a decrease in chlorophyll a/b values from 2.079/0.618 mg/g by weight to 1.272/0.293 mg/g and from 3.125/0.896 mg/g to 1.76/0.453 mg/g for strawberries and roses, respectively. The positive effect of SiO₂ NPs at concentrations of 4.0 and 5.0 mg/l on adventitious shoot formation in fig explants was shown. It was revealed that the studied concentrations of TCP NPs affected the plant habitus, but did not contribute to shoot formation. There was no significant effect of the studied concentrations of NPS Se, SiO₂ and Ca₃(PO₄)₂ on the induction of shoot formation of the studied crops.

The staff of the Nikitsky Botanical Gardens conducted a detailed soil and dendrological examination on the growth of southern magnolia (Magnolia grandiflora L. ) in the Alupka Park. The objective of this work was to identify the main edaphic factors affecting the growth and development of Magnolia grandiflora L. The characteristic of the morphological description of the most typical soil sections laid on the territory of the park under M. grandiflora with different vital conditions is given. Under the plants, the soil is fully provided with humus and nutrients. The effect of carbonates on the growth and development of M. grandiflora has not been reliably established (r=-0.56; n=6). According to the content of fragments of dense rocks (clay shales, sandstones, less often limestones), soils in the meter layer are weakly, medium and strongly gravelly-gritly. In the surveyed areas, the compacted soil (>1.4 g/cм³) compacts even more with depth and becomes very dense with low porosity (less than 45%) in a layer of 80-100 cm. The granulometric composition of the fine-grained soil on brown soils is heterogeneous throughout the site and was characterized mainly as heavy loamy with a predominance of coarse and fine dust. Such soils are considered favorable in terms of granulometric composition for most woody and shrubby plants, including southern magnolia. Optimal edaphic conditions for the cultivation of southern magnolia on agro-brown soils of the Alupka Park have been identified. These are soils with a light clay granulometric composition, an addition density of up to 1.52 g/cм³ and a content of up to 25% CaCO₃. This characterizes its relative tolerance and high ecological valence to edaphic conditions in comparison with deciduous species of magnolias growing on the Southern coast of Crimea. A high level of agricultural technology is the main method of improving the vital condition of M. grandiflora. 

The article presents the results of an assessment of the phytosanitary condition of the hybrid iris cultivars of the NBG–NSC collection, the dominant pest species have been identified and specified, the degree of their harmfulness has been established, and the nature of the damage depending on the phenological state of plants has been described. Research methods: The pest species composition was studied by visual inspection of generative and vegetative organs of plants 1 time in 7-10 days. The degree of harmfulness was assessed on a 3- point scale. Results and discussion. The dominant species of pests of irises were green rose chafer Tropinota hirta Poda, rose chafer Cetonia aurata L. , undulating flea beetle (Phyllotreta nigripes F. ), which damages leaves, leaf beet aphid Aphis fabae Scopola belonging to the orders from the class Insecta Coleoptera, Hemiptera and two representatives from the class Gastropoda Pulmonata – species of gastropods Helix albescens  (Rossmässler, 1839) family Helicidae and Parmacella ibera (Fischer, 1856) family Parmacellidae