The influence of the intensity and spectral composition of LED and fluorescent (FL) light on the morphogenesis of Myrtus communis L. and Psidium cattleianum Sabine (Myrtaceae) seedlings in a small pot greenhouse culture in the Central Botanical Garden of the National Academy of Sciences of Belarus (CBG) was studied. It was shown that in terms of plant height, the number and total surface of leaves, as well as the specific dry weight of the leaf, seedlings of both species over 120 cultivation days in all variants with irradiation surpassed control plants. The increase in dry weight per 1 cm² of leaf (mg with respect to the control) that characterizes the photosynthesis productivity was influenced by the spectral composition of radiation, which made it possible to identify interspecies and intervariant differences. The variant with an FL Narva lamp with a total photon flux density PFD = 76.22 µmol/m²/s, with a share of the green spectrum PFD-G = 46.47 %, red – PFD-R = 20.00 % and with the value of the ratio R/FR = 5.77 in the subtropical long-day species M. communis, it was 1.24 mg, while in the tropical short-day species P. cattleianum had only 0.39 mg. In plants irradiated with an LED lamp with a photon flux density PFD = 186.20 µmol/m²/s, with a share of PFD-R = 59.34 %, and at R/FR = 54.43, the growth was 2.60 and 1.93 mg with respect to control, respectively. LED sources are the most efficient in terms of the photosynthesis productivity for both short-day and long day plants.

   The advantage of FLORA LED lighting in comparison with HPS lamps for cultivation of tall tomato varieties under production conditions is shown. Under LED illumination with well-balanced spectral composition, the main growth and physiological parameters of tomato juvenile plants (such as dry weight and accumulation of dry matter of vegetative organs, content of photosynthetic pigments, rate of oxygen release during photosynthesis, coefficient of photosynthetic efficiency, time of flowering onset) were superior to plants grown under HPS lamp illumination. It is assumed that increased photosynthetic activity, as well as more intensive growth and development processes provided a higher adaptive potential and survival during transplantation, early fruiting. and higher yields to plants grown under LED lighting.

   The species composition and abundance of macrozoobenthos of the Neman River within the borders of the Grodno region have been studied. A total of 165 identified lower detectable taxa (NOTES) of macrozoobenthos representatives belonging to 3 types of aquatic invertebrates were found: Mollusca – 30, Annelida – 12, and Arthropoda – 123 NOTES. Prior to the species, 119 taxonomic elements were detected. The average number of identified lower detectable taxa in the studied Neman River beds was 20.75 NOTES. The average number of macrozoobenthos representatives in the studied sections of the Neman River reached 857.5 specimens. Among the collected aquatic invertebrates, invasive species were identified – Lithoglyphus naticoides (Pfeiffer, 1828), Dreissena polymorpha (Pallas, 1771) and Orconectes limosus (Rafinesque, 1817). A rare species found in Belarus only for the third time is the mayfly Ametropus fragilis Albarda, 1878. Dragonflies Anax imperator Leach, 1815 and Gomphus flavipes Charpentier, 1825 were protected in Belarus and in a number of Western European countries.

   The syntaxonomic structure of Magnocaricetalia order in the Belаrusian Lakeland was studied during 2010–2021 years. 60 descriptions of 21 lakes were analyzed according to the Braun-Blanquet method. It was found that the syntaxonomic structure of Magnocaricetalia order contains 3 unions, 9 communities, and 7 variants. Coenoflora of Magnocaricetalia order includes 52 species; the largest flora is typical for Caricetum gracilis association that contains 23 species. Mesotrophic lakes have 8 associations, eutrophic and distrophic lakes have 5 and 4 associations, respectively. The Equiseto fluviatilis-Caricetum rostratae community is the most distributed and is revealed in 13 lakes. Based on the results of this research and the literature sources, the total syntaxonomic structure of Magnocaricetalia order for the Republic of Belarus will include 3 unions and 18 associations.

   Respiratory diseases occupy a dominant position in the structure of morbidity, often the etiology of which remains unclear. This situation is largely due to the lack of knowledge of the entire spectrum of pathogens that cause respiratory diseases, as well as the lack of approaches to their indication and identification. Thanks to constant progress of molecular biology, a number of bacteria related to chlamydia have been identified, some of which are associated with human respiratory diseases, including chlamydia-like microorganisms. The role of atypical pathogens such as chlamydia-like microorganisms Parachlamydia acanthamoebae, and Simkania negevensis in the pathology of the human respiratory tract is still not fully understood. A real-time PCR-based method has been developed and optimized. It is capable of detecting the DNA of both chlamydia and chlamydia-like microorganisms (Parachlamydia acanthamoebae and Simkania negevensis). The method is characterized by high specificity and reproducibility, as well as by analytical sensitivity at a level of 8.7∙103 GE/ml. Its use will make it possible to assess the contribution of these atypical pathogens to the etiological structure of infectious diseases of the respiratory tract.

   The article presents the data on the survival and morphometric parameters of annual grafted plants using the grafting by a double-side cut on the handle leaving a bark strip on the rootstock into a split of a semi-lignified shoot and using the grafting by cutting during the growing season into a split of a green shoot. Pinus sylvestris “Yellowish”, “Carolina”, “Elegant” that were obtained by breeding in the Central Botanical Garden of the National Academy of Sciences of Belarus and Pinus mugo “Carstens Wintergold” were used as model objects. It has been established that the method of double-sided cut on a scion for grafting decorative forms of Pinus sylvestris L. is the most effective. This method provides a survival from 86.4 to 100 % and optimal crown development. Grafting into a split of a semi-lignified shoot is recommended when using lignified cuttings after long-term storage. This approach provides a survival of about 60 %. Grafting into a split of the green shoot can be used when harvesting cuttings during the growing season and provides a survival rate of 8.7 to 72.7 %.

   The effect of selenium and silicon in nanoform in comparison with sodium selenite and sodium silicofluoride on the growth of pathogenic fungi Fusarium avenaceum and Bipolaris sorokiniana was evaluated. The influence of nanoparticles on wheat and corn seed germination and seedling growth was also studied. The inhibitory effect of selenium and silicon nanoparticles on the growth of Fusarium avenaceum and Bipolaris sorokiniana was revealed. Nanosilicon at a concentration of 5–50 mg/l inhibited the growth of pathogenic fungi Fusarium avenaceum and Bipolaris sorokiniana to a greater extent than selenium nanoparticles and was more effective than sodium silicofluoride. Fusarium avenaceum was shown to be more resistant to nanoselenium and sodium selenite compared to Bipolaris sorokiniana. Nanoparticles had practically no effect on seed germination and the growth of wheat and corn seedlings, while sodium selenite and sodium silicofluoride at the same concentrations caused a decrease in seed germination energy and dry weight of the shoots and roots of seedlings.

   In this work we was studied the trophic structure of the zoobenthos of Lake Lukomlskoye. Five trophic structures have been recorded in the lake: collectors, predators, active filter feeders, scrapers and shredders. Collectors, predators and active filter feeders had the highest specific abundance. A decrease in the proportion of active filter feeders and an increase in collectors in the heated zone was established.