University proceedings. Volga region. Natural Sciences

Background. Siberian dwarf pine (Pinus pumila) has an extensive range (about 6 million km2), occupying the first place among the five-coniferous pines. Pinus pumila plays an important ecological and economic role due to its high adaptability to extreme conditions and valuable properties of seeds rich in biologically active compounds. Materials and methods. The morphometric parameters of cones, the number of fertile and sterile scales, as well as the proportion of developed and underdeveloped seeds were determined during the study. The conducted studies revealed that the size of cones in the Irkutsk region exceeded those in Chukotka by 15–26 %. At the same time, the indicators of seed productivity in the Chukotka Autonomous Region were statistically slightly higher (67–92 % versus 69–86 % in the Irkutsk Region). The maximum yields were recorded in 2020 and 2022, while in 2023 there was a decrease in the level of fruiting. It was found that the proportion of morphologically underdeveloped seeds in the Chukotka Autonomous District was higher, which was probably due to the combined effects of adverse climatic factors and anthropogenic environmental pollution. Results and conclusions. The results of the study confirm the high seed productivity of Siberian dwarf pine, despite the extreme growing conditions. The data obtained has implications for reforestation, landscaping, and biodiversity conservation in the northern regions, as well as for use in pharmacology and medicine.

Background. The study of the bumblebee fauna in Penza region can inform the development of regional policies for sustainable environmental management, including biodiversity conservation. The purpose of the study is to compile an annotated inventory of bumblebee collections from Penza region and analyze their species richness and distribution. Materials and methods. The collection of the Department of Zoology and Ecology includes bumblebees gathered by teachers, staff, and students of Pedagogical Institute during field practices and expeditions, as well as by employees of the “Privolzhskaya Lesostep” Nature Reserve and schoolchildren. Specimens were collected at 174 locations across Penza region. 2357 bumblebee specimens were processed. The collection material is documented in an annotated list specifying: geographic collection site, number of specimens (♀ and ♂), biotope, and collection date. Results. 34 bumblebee species from 11 subgenera were recorded. The subgenera with the highest species richness were Thoracobombus (10), Psithyrus (8), Bombus (3), and Subterraneobombus (3). The remaining subgenera comprised 1-2 species each. Dominant, widespread, and rare species were identified. DNA barcoding enabled the identification of B. cryptarum from the Bombus lucorum complex, a species not previously reported in adjacent territories. The highly variable species B. humilis and cuckoo bumblebees of the subgenus Bombus (Psithyrus) were analyzed in detail. Conclusions. An annotated checklist of bumblebees of Penza region has been compiled. Analysis of literature data on the local bumblebee fauna suggests that the collection is incomplete. Specimens of B. deuteronymus and B. jonellus, previously reported in publications, are absent from our collection. The species composition of bumblebees in the region is close to the fauna of the adjacent Ulyanovsk Region.

Background. Understanding the patterns of distribution of organisms in different types of biotopes is one of the main tasks of ecology. This task is especially relevant in relation to single-celled organisms, which remain insufficiently studied. Freshwater testate amoebae are used as a model object for such studies. The purpose of this study was to investigate the species composition and structure of testate amoebae communities within the highly macroscopically homogeneous sphagnum raft of bog complexes in the forest zone of the Kamchatka peninsula. Materials and methods. The material for the work was the results of a study of surface samples of sphagnum mosses, which were collected in the territory of three bog ecosystems of the Kamchatka peninsula. In the laboratory, the samples were processed according to a method based on filtering and settling of aqueous extracts, to study the species composition and structure of testate amoebae communities. All found specimens of testate amoebae were analyzed in aqueous suspensions using an inverted microscope of the Biomed-6PR model at a magnification of ×250. To identify the nature of the differences between local communities, species ordination was performed using the principal component analysis method based on the values of relative abundances of species. Results. As a result of the conducted research, 103 species and intraspecific taxa of testate amoebae were found. In the studied communities, the dominant ones are typical sphagnobiont and eurybiont representatives of testate amoebae, which are characterized by a wide geographical distribution. The main differences in the species composition of testate amoebae communities are determined by the humidity of the biotopes. In Swamp No. 2 and Swamp No. 3, transitional variants of communities are noted, and Swamp No. 1 is characterized by the most hydrophilic community. Conclusions. The conducted research showed that on the Kamchatka Peninsula, testate amoebae are a rather diverse and quite common component of swamp ecosystems. Features of the hydrological regime play a major role in the differentiation of communities in the studied ecosystems. In the swamp ecosystems of the Kamchatka Peninsula, the species composition of testate amoebae communities is formed by typical species that are characteristic of most similar biotopes.

Background. Microbe-plant interactions are a well-known mechanism in science and practice for activating growth and increasing productivity in agricultural crops. The purpose of this study was to evaluate the effect of a suspension of the Pseudomonas sp. GEOT18 strain, applied with phosphate fertilizers, on the morphophysiological parameters and productivity of common barley (Hordeum vulgare L.). Materials and methods. The effect of the strain suspension on the growth and productivity of H. vulgare cultivar Sonet was studied through field trials in 2020 and 2022, and the strain's performance under additional phosphorus fertilizer application was assessed in 2023–2025. The strain suspension was applied twice: by seed bacterization before sowing and by spraying the phyllosphere during the tillering phase. Results. Long-term field experiments suggest that a suspension of the Pseudomonas sp. GEOT18 strain increases the assimilation surface, the content of photosynthetic pigments, and the accumulation of dry matter in aboveground organs, both alone and under conditions of additional phosphate nutrition. Grain productivity of H. vulgare variety Sonet in the Non-Chernozem zone of Russia in experimental variants exceeds the control by 16–39 % when applying a suspension of the strain and by 72–113 % when applying a suspension of the strain together with mineral fertilizers (by 5–12 % relative to variants with the application of the same doses of phosphate fertilizers, but without using a suspension of the strain). The effect of the Pseudomonas sp. GEOT18 suspension may be associated both with the ability of bacteria to synthesize IAA (7.87 ± 0.71 mg/l) and to release phosphorus from insoluble calcium phosphate into a form accessible to plants. Conclusions. The obtained results allow us to consider a suspension of the Pseudomonas sp. GEOT18 strain as a basis for the development of a biopreparation..