The purpose of the research was to evaluate 15 samples of spring filmy oats in a collection nursery according to the yield and adaptability parameters. The research was carried out in 2022–2024 in the conditions of the Kirov region (VolgaVyatka region). The "year" factor had the greatest impact on the yield – 60.1 %. The index of environmental conditions (I_j) ranged from +105 to -151 over the years. On average, over the years of the research, high yields were formed by samples  k-15340 ‘Uran’ (541 g/m²), k-3969 0122 (539 g/m²), k-3967 0144 (531 g/m²). Samples with high stress resistance (U₂ - U₁) were identified – k-15495 ‘Vsadnik’ (-94), k-3967 0144 (-175), k-15498 ‘Uralets’ (-196); with high genetic flexibility  (U₁ + U₂)/2 – k-3969 0122 (517), k-15340 ‘Uran’ (509), k-3967 0144 (504). The highest total adaptive capacity (TAC_i) was found in samples k-15340 ‘Uran’ (41), k-3969 0122 (39), and k-3967 0144 (31). According to the set of indicators, the most stable samples were identified – k-15495 ‘Vsadnik’, k-3967 0144, k-15498 ‘Uralets’ (compensation coefficient (K_gi) – 0.08–0.34; relative genotype stability (S_gi) – 9.8–22.3 %; variants of specific adaptive ability (σ²_CASi) – 47.9–101.8; stability factor (SF) – 1.22–1.57). Samples k-15495 ‘Vsadnik’, k-3967 0144, k-15291 ‘HETMAN’, k-15498 ‘Uralets’, k-15429 ‘CWAL’, and k-15496 ‘Stipler’ were characterized by weak responsiveness to changes in environmental conditions (linear regression coefficient (b_i) – 0.33–0.97). Samples 15495 ‘Vsadnik’, k-3967 0144 (breeding value of genotype (BVG) – 398.6–343.8) had high stability according to the "yield" trait.  A very high positive correlation was found between the values of yield and TAC_i (r = 1.00). Collection samples k-15495 ‘Vsadnik’, k-15498 ‘Uralets’ (Russia), k-15429 ‘CWAL’ (Poland), k-3967 0144 (USA) which received the lowest amount of ranks (30-52) when ranked in terms of adaptive ability are of interest for further breeding work.

Modern breeding of spring oats is aimed at realizing the productivity potential of the cultivar in various environmental conditions. The purpose of the research is to study 19 hulled samples of oats in a collection nursery and use cluster and correlation analysis to identify genotypes with valuable economic and biological characteristics. The studies were conducted in the Arkhangelsk Region (Northern Region) in 2022–2024 under various meteorological conditions during the vegetation periods (hydrothermal coefficient – 1.1…1.7). Samples from the collection of the Federal Research Center All-Russian Institute of Plant Genetic Resources named after N. I. Vavilov were evaluated according to 6 characteristics (grain yield, duration of the "germination-wax ripening" period, productive bushiness, grain weight per panicle, number of grains per panicle, and weight of 1000 grains), which were entered into the cluster analysis program. The distribution of oat samples by clusters was unstable in different years of the research with the exception of the standard cultivar ‘Arkhan’ (I cluster). Filmy oat samples included in clusters I-II are of the greatest interest for use as sources of agronomic traits according to the mass of 1000 grains (37.4–42.7 g): URS CORONA, URS GUAPA, URS BRAVA, URS CHARRUA, ‘Arkhan’ standard; according to the lacustrine content (64.1–76.5 pcs.): UFRGS 21, UFRGS 02 6017-1, UFRGS 17, ‘Arhan’ standard; by precocity (74–76 days): ‘Skorospely 1’, ‘Skorospely 2’ , URS GURlA, URS TORENA, URS GUAPA, URS CHARRUA, UFRGS 03 7034-1. Correlations between the number of grains per panicle and grain weight (r = 0.91, p ≥ 0.001) and yield (r = 0.45, p ≥ 0.05) have been established.

The article presents the results of a comparative study of the new potato cultivar ‘Zabiyaka’ for 2020–2024 in the agroecological conditions of the Kirov region (Volga-Vyatka region) according to the main economically valuable characteristics. As a standard, the middle early cultivar ‘Nevsky’ (Russian Potato Research Centre) was used. The new cultivar was developed by artificial hybridization by clone selection from a hybrid combination (‘Aurora’ x ‘Kiwi’) under a joint cooperation agreement with the breeding center of the Russian Potato Research Centre. According to the results of the competitive variety testing, the ‘Zabiyaka’ cultivar was statistically significantly superior in yield to the standard ‘Nevsky’ cultivar (18.5 t/ha) and the ‘Virage’ cultivar (20.5 t/ha), previously included in the State Register of the Russian Federation. The average yield of the new cultivar was 25.7 t/ha, maximum – 30.4 t/ha. The new cultivar showed high adaptability to cultivation conditions (adaptability coefficient 1.19) compared to other cultivars (‘Nevsky’ – 0.86, ‘Virage’ – 0.95). Table cultivar ‘Zabiyaka’ with good taste (4.2–4.7 points), the average starch content over the years of testing was 14.6 %, the maximum – 15.7 %. The color of the tuber pulp is cream. According to the data of the All-Russian Testing Station for Potatoes Resistance to Cancer and Potato Nematode the ‘Zabiyaka’ cultivar is resistant to common potato cancer (pathotype I) and golden cyst-forming potato nematode (R01). Based on the results of many years of breeding work in 2024, the middle early potato cultivar ‘Zabiyaka’ was transferred to the state variety testing (application No. 91514/7553347, priority date 08.05.2024). The new cultivar is offered for cultivation in the Volga-Vyatka region.

Scientific research on potato breeding is aimed at increasing crop yields and the resistance of cultivars to diseases and pests, as well as improving product quality. Based on the results obtained, statistical models are developed that allow not only to create a system for forecasting the parameter under study, but also to explain the contribution of individual traits that form this parameter. The aim of the study is to determine the optimal model for forecasting potato yield based on the analysis of agronomic traits (average tuber weight per a potato plant; the number of tubers per a plant; content of starch, protein, total and reducing sugars, vitamin C and nitrates in tubers) of 100 potato cultivars harvested in 2024 (Sverdlovsk Region). In this work, a linear regression model of potato yield (t/ha) was developed with three predictors: average tuber weight (g), the number of tubers (units) and natural logarithm of nitrate content in tubers (mg/kg). The resulting model was able to predict 77.9 % of the data dispersion (R² = 0.785, R²_adj = 0.779, p<0.001), by this the degree of model fit was ideal, since the mean absolute error MAPE was less than 10%. The regression model assumptions were tested using the LINE algorithm: linearity, independence, normality, homogeneity. This algorithm proved the adequacy of the obtained model. Using the linear regression method, it was shown that with an increase in the average weight of marketable tubers by 1 g and the number of tubers by 1 unit, potato yield increased by 0.314 and 2.386 t/ha, respectively. However, with an increase in nitrate concentration per unit of natural logarithm, the yield decreased by 3.63 t/ha. While tuber weight and tuber number had a functional relationship with the yield, nitrate content had only an indirect relationship. According to the literature, the nitrate concentration in potato tubers at the end of the harvest represents a «final assessment» of the efficiency of nitrogen use by a particular cultivar throughout the growing season. The model obtained determines the selection criteria for breeding high-yielding potato cultivars: selection of genotypes with a large number and weight of tubers, low residual nitrate content in tubers under standard nitrogen nutrition conditions.

Tomato is the most popular vegetable crop and its fruits are consumed fresh and as processed products. For each type of use, cultivars with specific fruit qualities are required. The objective of the research was to study new tomato cultivars bred by the All-Russian Research Institute of Irrigated Vegetable and Melon Growing according to the complex of agronomic traits in a competitive trial nursery. The studies were conducted from 2022 to 2024 under the conditions of the Astrakhan region. The objects of the study were new tomato cultivars ‘Krasny naliv’, ‘Rozovy sharm’, and ‘Ozarenie’, as standard there were used cultivars ‘Astrakhanskij’ (with round fruits) and ‘Torpeda’ (with elongated, plum-shaped fruits). According to the results of the competitive variety trial high productivity and adaptability of the studied cultivars in the agro-climatic conditions of the Astrakhan region have been established. In a comparative analysis with the standard ‘Astrakhanskij’ cultivar in the group of salad-type varieties the highest yield indicators were recorded for the ‘Krasny naliv’ cultivar (71.6 t/ha) that was 1.8 t/ha higher than the standard. This, combined with a better marketability indicator (97.9 %), allowed it to be identified as the most promising. The ‘Rozovy sharm’ cultivar was 5.3 t/ha less than the standard in the yield (64.5 t/ha), but surpassed it in marketability by 1.1 % (95.7 % versus the standard's 94.6 %). In the second group, the new cultivar ‘Ozarenie’ 1.8 t/ha exceeded the standard ‘Torpeda’ in the yield (51.6 t/ha) but was slightly inferior in terms of marketability. It was established that the adaptability coefficient of all studied genotypes, including the new cultivars and the standards, varied around one. This characterizes them as highly adaptive, which is manifested in their ability to produce consistently high yields due to the resistance to the complex of unfavorable biotic and abiotic environmental factors characteristic of the Astrakhan region. The introduction of these cultivars into production will help to expand the assortment and support import substitution for this crop.

Flax is a promising crop oriented towards industrial use and export. Traditional breeding methods require significant time and labor resources, but modern DNA-markers such as microsatellites significantly accelerate the development of new cultivars and increase the efficiency of breeding processes. The aim of the work was to develop approaches to marker-associated breeding using SSR-markers for flax. The objects of the study were twenty-four lines of fiber flax obtained as a result of the implementation of the breeding and seed-production center project, for which genetic passports were compiled, genetic homogeneity was assessed and phylogenetic relationships were considered. DNA from 25 plants of each line was subjected to SSR analysis by PCR method using two experimental marker lines developed in Russia and Belarus. The PCR-products were detected using capillary electrophoresis with subsequent cluster analysis and construction of dendrograms. SSR-analysis revealed a high level of polymorphism: 32 alleles in the Russian and 47 in the Belarusian line, with unique alleles in individual genotypes. Intravarietal homogeneity was 76–96 % when analyzed by two lines of SSR-markers, which confirmed the genetic stability of the lines. Molecular genetic passports were formed based on the data. Cluster analysis performed for each marker set divided the lines into three main clusters, reflecting their origin. Both sets of markers showed comparable resolution, ensuring complete differentiation of samples and reliable construction of phylogenetic relationships. At the same time, the Belarusian line of markers proved effective in identifying hidden genetic variations, while the Russian line is preferable for monitoring stability and homogeneity when registering the cultivars. Further use of SSR-markers is advanced and can help in monitoring flax breeding processes and protecting the rights of plant breeders.

Representatives of the genus Thymus (thyme) are widely used in folk medicine as anti-inflammatory, expectorant, antibacterial agents. However, two species of thyme are pharmacopeial and approved for use in scientific medicine: T. serpyllium L. and T. vulgaris L., therefore, the study of other species is promising for expanding the resource potential of representatives of this genus. The research provides the results of studying the chemical composition and some commodity quality indicators of raw materials (humidity and total ash) of four taxa of the genus Thymus: T. serpyllum L., T. marschallianus Willd., T. pseudonummularius Klokov & Des.-Shost., T. caucasicus Willd. ex Benth., which have been cultivated for more than 20 years in the South-Ural Botanical Garden-Institute of the UFRC RAS in the collection "Aromatic Garden". It has been established that the commodity quality indicators of the raw materials of the studied thyme samples meet the requirements of the pharmacopeial monograph (GM 1.5.3.0007.15). Analysis of the chemical composition of the studied thyme samples has shown that they contain biologically active substances important for spicy-aromatic plants - essential oils (0.88–1.37 %), tannins (8.15–12.48 %), ascorbic acid (0.069–0.102 %), organic acids (2.19–3.58 %), flavonoids (1.73–2.38 %). The leading position in all indicators of the conducted chemical analysis is occupied by T. marschallianus, which is superior to the pharmacopeial species (T. serpyllum) and can be recommended as an alternative source of raw materials for expanding the raw material base and further studying this species from other regions of the Russian Federation according to the indicators of the type sections of the pharmacopeial article "Identification" and "Tests."

Chuvash Research Institute of Agriculture has the only collection of world hop cultivars in Russia, which is a source of genetic material for breeding work. The purpose of the research is to identify the collection cultivars of common hop that are most adapted to the conditions of the Chuvash Republic (the central part of the Volga-Vyatka region) according to the yield of hop cones and the content of alpha acids in them. The article presents the results of 2022–2024 research. The adaptability of hop accessions was assessed by the coefficients of adaptivity (KA) and variation (CV). It was revealed that out of 240 accessions of hop collection, 70 samples exceeded the corresponding ripeness groups by the average yield and 33 samples – by the alpha acid content. According to the yield, ‘Yugoslavskiy krasnostebelny’ , ‘Forvard’ and ‘Galinskiy’ stood out among the early–ripening cultivars (2.22–2.58 t/ha; KA – 130.5–149.3 %), among the medium-late – ‘Marynka’ cultivar (2.92 t/ha; KA = 155.4 %), among the late-ripening – 18 samples including ‘Frisku’, ‘Hallertau Magnum’, ‘Atlas’, ‘Eurhop’, ‘Amerikanskiy’, ‘Petham Goling’ and OZ-79 (2.61–2.79 t/ha; KA˃ 130 %). According to the alpha acid content in hop cones (5.4–7.5 %), many cultivars were characterized by KA˃150 %. According to the complex of traits, 9 adaptive hop samples were identified, in which, during three years of testing, the coefficient of adaptivity exceeded 100 % in terms of both the yield and the amount of alpha acid in cones: mid-early – ‘Karlik 72’ and ‘Fakir’ (Russia), mid-ripe – ‘Flagman’ (Russia), ‘Spolechny’ (Ukraine), ‘Willamette’ (USA), ‘Shpaltsky’ (Germany), ‘Early Bird’ (England), late-ripening ‘Northern Brewer’ and ‘Braustern’ (Germany). These cultivars can be used as an excellent genetic material for breeding work.

Shallot (Allium ascalonicum L.) is currently a highly sought-after crop, enjoying widespread demand. In the Kirov region, breeding efforts are underway to develop new cultivars resistant to the abiotic and biotic factors of northern European Russia. These cultivars will enable the production of large, marketable bulbs when grown from seed, as well as facilitate seed production. This article presents the results of studies on the seed productivity of new cultivars obtained through individual and clonal selection from hybrid populations adapted to local conditions. It has been established that high-quality, commercialquality shallot seeds can yield 0.8–10.7 g per plant. The dynamics of the onset of the main phenological phases of mother plant development in various shallot cultivars was studied in 2021–2023, and the effect of weather conditions on their duration and seed productivity of plants was determined. It was found that the vegetation period of the studied shallot breeding accessions from regrowth to seed harvesting averaged 118 days over three years, and 142 days to full seed ripening. Promising accessions include: 187, 212, 214, 216, and 217 with a seed germination rate of over 75 %, which equates to the "elite seeds" category; as well as 195, 219, and the ‘Grant’ cultivar with a germination rate of over 55 %, which corresponds to the "first generation reproductive seeds" category.

Septoria tritici blotch is one of the most common and harmful diseases of spring wheat, causing a decrease in yield by 35–50 %. For successful breeding for resistance to this disease, stable source material with molecular and genetically identified Stb genes is needed. The purpose of the research is to search for donor varieties of these genes and sources of resistance of spring soft wheat to the causative agent of septoria Zymoseptoria tritici. There were analyzed 146 cultivars of spring soft wheat from the world's VIR collection using molecular genetic methods for the content of the Stb2, Stb9, Stb11 and Stb13 genes, as well as for resistance to infection with common strains of the causative agent of the disease. Using PCR, the desired genes were identified in 57.7 % of the studied cultivars. The occurrence of Stb2, Stb9, Stb11, and Stb13 genes in the studied genotypes was 14.3 %, 55.9, 67.9 and 79.8 % respectively. All four genes have been identified in the ‘Tepsey’ and ‘Eminent’ cultivars. As a result of laboratory evaluation of donor varieties with artificial infection, 4 highly resistant cultivars were identified (‘Kinelskaya Yubileynaya’, ‘Ingala’ (Russia), ‘Vesta’ (Belarus), ‘Hua Mai 10’ (China)) and 11 resistant cultivars with delayed disease development (‘Ekada 70’, ‘Uralskaya Kukushka’, ‘Pamyaty of Yudin’, ‘Khutoryanka’, ‘Ulianovskaya 105’, ‘Krasnoyarskaya 12’, ‘Voloshinka’, ‘Lada’ (Russia), ‘Dai Chun 2’, ‘Yanzhan No. 1’, ‘Long Chun 8’ (China)). It can be assumed that the Stb13 gene plays a certain role in the formation of resistance of spring wheat against the strains used for infection. A significant increase in yield from 1 m2 to the standard ‘Bazhenka’ cultivar was noted in ‘Ingala’, ‘Vesta’, ‘Ekada 70’ and ‘Ulianovskaya 105’ cultivars. These collection samples of spring soft wheat can be involved in the breeding process as highly productive donors of the identified Stb genes.

Ensuring the production of high-quality crops determines the need to develop new environmentally safe approaches in the biological control of the spread of phytopathogens. The aim of the work was to study the biocontrol properties of monocultures and complexes of the fungus Trichoderma atroviride and diazotrophic bacteria Fischerella muscicola and Azotobacter chroococcum in relation to the phytopathogen Fusarium culmorum R/z-16, to evaluate the environmental safety of the antagonist strains used. For the first time there has been studied the ability of T. atroviride complexes and diazotrophs to biocontrol F. culmorum, the main causative agent of root rot in grain crops, in the soil. A model experiment to identify the biocontrol activity of strains was carried out in microcosms with soil inoculated with the studied microbial cultures. After 45 days of incubation, spring wheat (Triticum aestivum L.) of the ‘Bazhenka’ cultivar was sown on the soil surface and 7 days after the sowing, the growth and infection rates of the seedlings were evaluated. It was found that the complexes of T. atroviride + A. chroococcum + F. muscicola, as well as T. atroviride + F. muscicola had the strongest biocontrol effect, which reduced the development of root rot by 4.12–4.97 times relative to the infectious background without the introduction of antagonists. Under the influence of trichoderma and diazotrophs on an infectious background, the dry weight of wheat seedlings increased by 72.9 % compared with soil inoculation with F. culmorum monoculture R/z-16. The ecological safety of filtrates of liquid cultures of T. atroviride K-01P (dilution 1:100), F. muscicola 300 (dilution 1:10-1:100) for the preparation Ecolume and Daphnia magna crustaceans has been confirmed. Field research data for 2022-2023 indicate the absence of a negative effect of T. atroviride K-01P and F. muscicola 300 on native representatives of micromycetes and ammonifying bacteria in the soil of the root zone of wheat. The results of the study expand traditional ideas about the possibility of using fungi of the genus Trichoderma and diazotrophs in the biological control of fungal phytopathogens and determine the prospects of using microbial complexes based on them in agriculture.

The relevance of developing functional products based on secondary raw materials is due to trends in increasing the environmental and economic efficiency of the food industry. The possibility of including grain-blackcurrant distillers’ stillage in the composition of extruded crispbreads based on wheat flour as an ingredient with a high content of protein, dietary fibers and phenolic compounds was studied. The aim of the research was to study the effect of the dosage of grain-blackcurrant stillage on the extrusion modes in obtaining extruded crispbreads, the physicochemical and organoleptic characteristics of the products. Mixtures containing up to 20 % grain-blackcurrant stillage were extruded at 155 °C, 17 % moisture content, and constant productivity and screws speed. In terms of process parameters, a reliable decrease in pressure in the pre-matrix zone was found from 4.5 to 3.5 MPa with an increase in the dosage of stillage in the recipe. Adding stillage reduced the hardness of the samples from 9.4 to 4.2–5.5 N and increased the number of microfractures, the product porosity index, from 4,0 to 9.9. Evaluation of the chemical composition showed that the addition of up to 20 % grain-blackcurrant stillage increases the protein content from 12.5 to 17.1 g/100 g, dietary fiber from 5.3 to 11.3 g/100 g, and phenolic compounds from 216 to 558 mg/kg. It was noted that there was no loss of phenolic compounds during the extrusion process; their content in the crispbreads exceeded the calculated values, apparently due to the destruction of high-molecular forms of bound polyphenols during thermomechanical treatment of the mixtures. The tasting panel (n = 22, five-point scale) assigned the sample with 10 % stillage the best ratings for taste (4.4), texture (4.3) and general appearance (4.6); at 20 %, an increase in bitterness was recorded (3.9). The addition of about 10 % grain-blackcurrant stillage ensures the production of crispbreads enriched with protein, dietary fiber and antioxidants, without deterioration of consumer properties, which opens up prospects for their use in healthy diets.

The article presents the results of 2023-2024 study on the effect of fertilizers on the yield of oil seeds, vegetable oil and feed protein in spring rapeseed of the ‘Forpost KL’ cultivar as well as on the economic efficiency of its cultivation technology in the Lipetsk region (in the forest-steppe zone of the Central Federal District of the Russian Federation). The field experiment variants were as follows: control – without fertilizers; N₄₀ + foliar fertilization (FF); N₆₀ + FF; N₄₀P₄₀K₄₀; N₈₀P₈₀K₈₀; N₄₀P₄₀K₄₀ + N₄₀; N₄₀P₄₀K₄₀ + N₄₀ + FF; N₄₀P₄₀K₄₀ + FF, N₈₀P₈₀K₈₀ + N₄₀ + FF. Complete mineral fertilizer was applied in autumn before plowing; nitrogen fertilizer was applied in spring before pre-sowing cultivation. Biostim Maslichny at a dose of 2.0 l/ha was used for foliar fertilization during the period between spring rapeseed stem extension and the beginning of budding. The soil of the experimental plot was heavy loamy leached chernozem. On average, over the years of the research, the seed yield of spring rapeseed cultivated without fertilizers was 1.80 t/ha, increasing by a statistically significant 0.26–0.74 t/ha when fertilizers were applied. The maximum values were obtained through agricultural practices involving the application of N₈₀P₈₀K₈₀ (2.38 t/ha), N₄₀P₄₀K₄₀ + N₄₀ + FF (2.42 t/ha) and N₈₀P₈₀K₈₀ + N₄₀ + FF (2.54 t/ha). These variants also yielded the highest oil and protein per-hectare yields (1049–1082 kg/ha and 611–668 kg/ha, respectively). However, the highest net income (33,720 rubles/ha), profitability (94 %) and low cost per ton of oil seeds (15,446 rubles) were achieved using a spring rapeseed cultivation technology with the yield of 2.32 t/ha, which involved applying N₄₀P₄₀K₄₀ in autumn before plowing and carrying out foliar fertilization with the organic-mineral fertilizer Biostim Maslichny.

The selection of a nutrient medium is one of the important factors affecting the yield and determining the quality of microgreens. During the experiment there was studied the possibility of using the remains of the life activity of black soldier fly larvae zoocompost (BSFLZ) as an organic supplement for growing sunflower microgreens under chemoponic conditions. The experimental design: control – filtered water; mineral fertilizer (1.5 ml/l); 1.0 % aqueous extract of BSFLZ (10 ml/l). Plants were grown in plastic containers for 7 days in a closed growbox under intensive light conditions and a controlled microclimate. The results showed that the addition of the BSFLZ extract increased sunflower shoot height by 20–23 % and resulted in the highest microgreens yield – 51 and 27 % higher in dry weight than growing in the control and mineral fertilizers. The biochemical composition of the microgreens varied depending on the treatment. In terms of total chlorophyll and phenol content, seedlings grown with the addition of the BSFLZ extract were slightly inferior to plants grown with a mineral fertilizer solution; however, they exhibited better carotenoid accumulation and a 15 % reduction in nitrate content. As with mineral fertilizers, the addition of the BSFLZ extract increased the total accumulation of macronutrients, particularly calcium, in the microgreens. Economic analysis confirmed the superiority of using zoocompost extract: net profit on organic matter was 6.7 times higher than on mineral-based ones.

A brief review of research on variation of thermal resistance of snow cover and formulas to determine the thermal conductivity coefficient of snow are presented. This article aims to establish the regularities of variation in thermal resistance of snow when compressive melioration is applied to the snow cover. A criterion consisting of ratio of initial thermal resistance to the thermal resistance after compression is introduced. Two practically relevant cases, a full and partial compression, whereby the snow density after compression is a constant and a variable respectively, are considered. It is demonstrated that the area where it can be assumed that the snow density after compression is a constant has a low confidence interval and in practical applications it needs to be accounted for that the snow cover is not fully compressed under load. The calculation results are presented in a generalized dimensionless form that includes an indicator of arbitrary exponent in an approximated formula to determine the thermal conductivity coefficient from snow density. It has been established that the type of functional dependence of thermal conductivity coefficient on snow density has a significant influence on the calculation results of the thermal resistance of snow cover. The boundary values of snow compression coefficient within the permissible error level (10 %) were found. For example, for a linear dependence of the thermal conductivity coefficient on density the permissible compression coefficient is no higher than 1.25. For a quadratic dependence, it is 1.11. The results of variant calculations are presented as 2D and 3D charts, which allow quickly assessing the assumptions and conclusions.

The objective of this study was to identify the relationship between ambient temperature and the productivity, mineral, and antioxidant status of bull calves during the early period of postnatal ontogenesis. The research was conducted in the Orenburg region on Black-and-White bull calves which were divided into three groups according to the season of their birth: Group I – winter calving season (December calving), Group II – spring calving season (March calving), Group III – summer calving season (June calving). Feeding and keeping were similar for all animals in the studied groups throughout the experimental period. It was found that, starting from 3 months of age, the bull calves in Group II surpassed their peers from Groups I and III in terms of live weight and average daily gain. The intensive growth of the bull calves was accompanied by an increase in the blood concentrations of glucose, total protein, albumins, cholesterol, erythrocytes, and hemoglobin. The animals in Group II were characterized by increased activity of superoxide dismutase and catalase against a background of a relatively low concentration of malondialdehyde. High ambient temperature contributed to increased concentrations of Hg, V, Cr, Pb, and As and decreased concentrations of Mg, P, K, Ca, Sr, Na, B, Mn, and I in the hair of bull calves from the summer calving season compared to those from the spring calving season. Bull calves from the winter calving season had intermediate concentrations of chemical elements between the mentioned groups.

There was conducted a study aimed at identifying genome-wide associations with phenotypic exterior traits in Holsteinized Black-and-White cattle (n=356 heads for 42,247 daughters). During the research there has been used the methodology of the Mosplem Union which includes 4 traits according to system A and 17 traits according to system B. Genotyping was performed on the basis of the Illumina BovineSNP50 (54609 SNPs). The search for candidate genes localized in the region of identified SNPs was performed in the NCBI database for the Bos_taurus_UMD_3.1.1 genome assembly. The CattleQTLdb database was used to search for QTL and areas under selection pressure. According to system "A" in the data region of significantly significant SNPs, 26 candidate genes associated with the studied exterior traits were identified. According to system "B", 22 SNPs associated with exterior traits were identified. The following genes are localized on chromosomes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 20, 21, 22, 25, 26, 28: ADCY5, FRYL, GOLGB1, ILDR1, ITGB5, MAPK10, SEC22A, STXBP5L, ZP2, ALDH1A2, ERGIC1, KCND2, PAPPA2, PPFIA2, PRDM16, RABGAP1L, SECISBP2, SMYD3, ANO3, DPP10, HPSE2, MAML3, PRKCE, SLCO3A1, ANTXR1, KCTD2, NCOA1, NRG3, TIGAR, VAV3, XYLT1, PRR5L, BFSP1, CDH4, HECW1, MAPKAP1, SPOCK1, SRP68, SYNJ2, DAB1, EPS8, PCDH15, PTPRR, TRPM7, TTYH2, UBR1, USP32, ANGPT1, ITCH, OSBPL10, RAI1, RGS22, SLA2, ZFHX4, BCL9, GFRA2, SLC25A12, CNNM2, IGFBP7, KALRN, MACROD2, PCSK5, UCK2, CNKSR3, CUL3, CYP27A1, RHPN1, TSNARE1, EBF1, PTCH1. The identified genes are associated with quantitative trait loci associated with various indicators that are consistent with those previously annotated by other researchers. The reliability of significant associations for point mutations was within the range of p<1.80E-08 – 0.0001474. Such a tool of genetic research as GWAS analysis allows more efficient planning of obtaining individuals that would meet the economic needs of dairy cattle breeding.

The aim of the research was to study the dynamics of progesterone concentration in the blood of heifers (n = 10) and lactating cows (n = 10) with signs of ovarian hypofunction after a single intramuscular injection of Progestamag® in a dosage of 10 ml. The experimental work was performed on animals of the Ayrshire breed. Ovarian hypofunction was determined by ultrasound sonography based on the absence of yellow bodies and large follicles. To determine the level of progesterone before administration of the drug and for 14 days after, venous blood was obtained from animals. The hormone concentration was determined by the enzyme immunoassay method. When calculating the pharmacokinetic parameters, the maximum concentration of the substance (C_max), the time of onset of maximum concentration (T_max), the half-life (T_1/2), as well as the elimination constant (K_elim) were determined. Based on the obtained data, dose-dependent changes in progesterone concentration were calculated using a linear method. It was found that after a single injection of the drug, there was a sharp increase in the level of the studied steroid. In heifers, T_max was observed on the second day, while C_max was 42.88 nmol/L, K_elim was 0.0083, and T_1/2 was 83.3 hours. A significantly high concentration of the hormone was observed for 9 days. The peak progesterone content in lactating cows also appeared after 48 hours, while the C_max was 24.96 nmol/L, K_elim was 0.0079, and T_1/2 was 88.1 hours.  Dose-dependent calculations showed that for 7...10 day sexual stimulation regimens in cycling heifers, the therapeutic range was from 1 up to 4 ml, and in cows from 2 to 7 ml of the drug. For the treatment of gonadal hypofunction, a volume of 2 to 6 ml can be considered a reasonable dosage for heifers, and from 4 to 7 ml of the drug for lactating animals. Thus, Progestamag® has a moderately prolonged effect, however, a gradual decrease in the level of the steroid over a long period of time may hinder the achievement of the rebound effect.

In connection with the development of antibiotic resistance in animal husbandry and the decrease in the effectiveness of existing treatment regimens for inflammatory diseases of the mammary gland in cows, the implementation of more effective preventive measures is an urgent task. The aim of the research was to study the effectiveness of 10 agents with different active ingredients (chlorhexidine, iodine, lactic acid) for udder teats treatment after milking. The work used clinical, microbiological, viscosimetric research methods, the agar diffusion method. Experimental studies were carried out on the basis of agricultural organizations of the Sverdlovsk region with different types of keeping and milking cows. For further studies 21 animals were selected. When examining cows with no clinical signs of mastitis, it was found that 47.6 % of animals had a subclinical form of mastitis. All samples of cow mammary gland secretion were contaminated with the following microorganisms: Staphylococcus aureus, Escherichia coli (non-pathogenic type), Enterococcus faecalis, Enterococcus faecium, Enterobacter spp., Streptococcus spp., Mucor. From the washes taken from the skin of the cow mammary gland teats, 55 isolates of microorganisms were isolated, among which the main etiologically significant agents in the development of inflammatory processes were: Staphylococcus aureus, Escherichia coli (non-pathogenic type), Enterococcus faecium, Enterobacter spp., Proteus spp. The studies have established that Staphylococcus aureus isolates were resistant to iodine- and lactic acid-based teat treatment agents after milking in 53.3 % and 46.7 % of cases, respectively; the minimum number of isolates (40.0 %) were resistant to agents that used chlorhexidine as the active ingredient. The effectiveness of chlorhexidine-based agents against Enterococcus faecium, Escherichia coli (non-pathogenic type), Proteus spp., Enterobacter spp. isolates was 62.5–87.5 %. Thus, the research has shown that chlorhexidine-based agents are the most effective for use in treating udder teats after milking as one of the stages of mastitis prevention.

The statistical parameters of the effective light absorption spectra of soybean seeds of various cultivars and ripeness groups were studied. The purpose of the research was to identify the varietal features and to develop an algorithm for varietal identification of soybeans according to the statistical parameters of absorption spectra during photoluminescence excitation. Spectral absorption characteristics were obtained using a CM2203 diffraction spectrofluorimeter in the wavelength range of λ = 230–600 nm. The statistical parameters of the spectra were calculated – mathematical expectation, variance, skewness and kurtosis. Effective light absorption during photoluminescence excitation occurs in the range from 300 nm to 550 nm with the main maxima at 420nm, 390 and 362 nm. Radiation absorption is caused by the presence of phenolic acids, carotenoids, riboflavin, as well as terpenoids, sporopollenin, lipofuscin, lignin, or flavonoids. The mathematical expectation and variance are determined with a relatively small relative error – no more than 1.2 and 7.6 %, respectively, and the errors in determining skewness and kurtosis can reach 16.1–22 %. By the magnitude of the asymmetry, the ‘Barguzin’ cultivar can be uniquely identified. The remaining studied cultivars can be identified with varying probability by all four statistical parameters. The ‘Vilana’ and ‘Vilana beta’ cultivars differ significantly in terms of variance. An algorithm for varietal identification based on the probabilistic identity of soybeans to known cultivars has been developed and a database of statistical parameters of soybean cultivars has been obtained. To increase accuracy, a combination of statistical and previously obtained integral absorption parameters is possible. In the future it is planned to increase the number of identified cultivars, clarify the ranges and develop an optoelectronic soybean varietal identification system.

Problems arising during the operation of hydraulically actuated systems caused by negative (accompanying) loads lead to reduced performance and possible failures in the supply of working fluid. The aim of the study is to develop modeling methods for drive systems with automatic compensation of the influence of accompanying load on the working elements of hydraulic equipment in agricultural machinery. The research methodology is based on mathematical modeling of hydromechanical systems of agricultural machines subjected to loads with variable direction, constructed through an analysis of force interactions within hydraulic drives. A mathematical model of a hydromechanical system with variable load is presented, based on an analysis of internal force interactions in hydraulic drives. Experimental studies confirmed the validity of the proposed mathematical models and identified rational design solutions for reducing the negative effect of load changes on the system. Various approaches to controlling the speed of hydraulic actuators subjected to external loads of variable direction are considered. The main results of the study are necessary for improving the performance of hydraulic drives in agricultural machinery such as wide-cut cultivators, stripping devices, and others, ensuring stable and controllable movement of working elements even under loads of alternating sign. Methods for calculating and designing hydraulic drives that maintain stable operation under changing load conditions have been developed. The advantage of using servo-type hydraulic locks with adjustable spool-type hydraulic resistance as the main component of the stabilization system is demonstrated, as they minimize the negative impact of variable loads on system operation. Experimental confirmation of the effectiveness of the proposed schemes and algorithms enables the application of the developed technologies in mass-produced agricultural machinery designs.