Vol 29, No 2 (2025)

The consequences of carrying out alternate strip fellings in mature and overmature secondary growth birch forests afer using the LP-19 felling and bunching machine are analyzed. It was found that the strips of birch forest 10…15 m wide left for completion of growing after the first stage alternate strip felling are not damaged by the wind, and due to side lighting, a second growth of spruce and fir undergrowth is formed there. It is shown that due to the high proportion of skidding tracks and destruction of the coniferous undergrowth due to the preliminary alternate strip logging, deciduous young forest growth are formed on the cut-down areas. It is recommended to give preference to traditional cutting technologies when carrying out alternate strip logging, and when using the LP-19 feller-buncher machine, logging should be carried out in winter in order to minimize the negative effect on the soil and maximize the preservation of coniferous undergrowth. Compliance with these recommendations will make it possible to transform mature and overmature secondary growth birch forests into primary conifers without artificial reforestation.

A molecular genetic analysis of two populations of Quercus robur L from the Volgograd region was carried out using ISSR and SSR analysis methods (the first population from the arboretum plantations of the Federal Research Center for Agroecology of the Russian Academy of Sciences, Volgograd, the second population from the Nizhnevolzhsky Experimental Station for tree breeding; Kamyshin). Nine of the 18 ISSR primers tested were found to be most effective for analyzing polymorphism within and between populations. The number of loci in the spectrum ranged from 4 to 10, depending on the primer. The UBC835 primer produced the largest number of loci in the spectrum (n = 10), and the greatest polymorphism (50…57 %) was found using UBC815, UBC834, UBC835, UBC836, and UBC840 primers. The main parameters of the genetic diversity of populations have been determined. It was found that all indicators were slightly higher in the first population (n_a = 1,75 ± 0,44, n_e = 1,44 ± 0,38, H_E = 0,25 ± 0,19). In the first population, polymorphism was higher by 10 %, meaning that the second population contains genetically more homogeneous trees. The electrophoregram obtained with UBC811 and UBC834 primers revealed unique DNA fragments characterizing variability within the species, which can be used in further breeding work. It has been shown that the use of SSR primers is less effective in assessing the polymorphism of these populations of Quercus robur L in comparison with ISSR primers. However, the microsatellite primers studied are species-specific, which makes it possible to use them, for example, in the genetic certification of a species.

Pre-sowing seed treatment is one of the most developed practices in agriculture. Despite this, reproducible positive effects have not yet been obtained with the use of stimulating preparations. One explanation may be that the consideration of seed stimulation was carried out in isolation from the soils and the microorganisms in them. To take into account these factors, the study of the efficiency for one of the stimulant classes — sorption-stimulating preparations (SSP), and also the development of approaches to the creation of effective stimulant preparations was carried out. The objects of the study were seeds of cultivars of spring and winter wheat, spring barley and winter rye. The tests were performed on sod-podzolic soil, changing its allelotoxic- ity due to sample preparation. The fixed indicator in assessing allelotoxicity, as well as the efficiency of SSP, was the total length of seed seedlings. Determination of the microbiological composition of soils was carried out using direct luminescent microscopy and seeding on nutrient media. During the experiments, it was found that an increase in the allelotoxicity of soil samples led to a noticeable decrease in the effects of SSP stimulation for spring wheat seeds. With the addition to the composition of the preparation of sucrose, which promotes the development of microorganisms, and an increase in the dose of the composition by 1,5 times, the effects of stimulation continued to decrease, reaching inhibition values for some varieties. On spring barley, an increase in the dose of the preparation, on the contrary, led to an increase in the efficiency of the SSP use. However, an increase in the values of the nutrients provision to an excessive level at which phytopathogenic fungi develop, showed that SSP with sucrose no longer stimulates, but inhibits the germination of seeds and the development of barley seedlings. Based on the data obtained, it is concluded that allelotoxins can enter seeds and developing plants not only from soils, but also from phytopathogens, therefore, the use of stimulants without limiting the development of phytopathogens does not solve the problem of protecting seeds from allelotoxins. To do this, it is proposed to use SSP together with fungicides. Laboratory experiments have confirmed the correctness of this approach — the use of SSP in conjunction with fungicides in all cases has a stimulating effect on the varieties and crops of cereals studied by us.

The lignin liquors recycling method to obtain yeast biomass by using the producer of baker's yeast Saccharomyces cerevisiae in the course of biosynthesis on a nutrient medium including waste from the pulp and paper industry such as lignosulfonates is described. It is shown that lignosulfonate, as a product of processing wood biomass, can be utilized in the process of bioprocessing in the presence of yeast into nutritious biomass, which is a protein ingredient for subsequent balancing, for example, of animal feed. Analysis of the carbohydrate composition of free sugars in the lignosulfonate part of the initial nutrient medium showed that the ratio of the main carbohydrates: arabinose, galactose, glucose, mannose, xylose, ribose and lactose was 1 : 1,6 : 1,8 : 6,4 : 12,5 : 0,1 : 0,02, which is likely to be used as a nutrient component in biotechnology. The methodology of biosynthesis was determined, optimal conditions for the process using lignosulfonate culture fluid were found, including (g/l of tap water): ammonium hydrogen phosphate — 1; potassium dihydrogen phosphate — 2; potassium hydrogen phosphate — 0,1; potassium chloride — 1,5; magnesium sulfate — 0,5; ammonium sulfate — 3; lignosulfonate — 2,5. It was shown that the process of yeast cultivation at a temperature of 35…40°C and pH 5,0 allowed obtaining a suspension containing 12…15 g/l of raw yeast cells in 8…10 hours, which can then be separated and used. The study of the amino acid and fatty-acid composition of the biomass confirmed the high biological value of the product, which may be of interest for use in cattle breeding.

The widespread use of microcrystalline cellulose in various industries and the production of polymer composites from it is due to the growing demand for it as an alternative to non-renewable and scarce fossil materials. Despite the fact that the production of microcrystalline cellulose still has some disadvantages, it has recently attracted increasing interest due to its renewability, non-toxicity, economic value, biodegradability, high mechanical properties, large surface area and biocompatibility. The article shows the possibility of obtaining microcrystalline cellulose from alternative sources of raw materials to expensive business wood — annual plants. Sulfate cooking of annual plant samples (industrial hemp and wheat straw) was performed in a laboratory autoclave under constant conditions: hydromodule 4,5; degree of sulfidity of the cooking solution 18 %; temperature 160 °C. To destroy the outer surface of the fiber shell, increase their active surface and reduce the cost of chemical treatment, the fibrous mass was ground in a semi-industrial disc mill (refining degree 15...85 °C). The water retention capacity of cellulose fibers from industrial hemp bonfires increased by 2,2 times, wheat straw by 2 times, the breaking length respectively by 64 and 52 %, and the penetration by 40 and 34 %. The cellulose samples were hydrolyzed with hydrochloric acid concentration of 73 g/l at 15 °C for 30 minutes and 54,75 g/l at 80 °C for 60 minutes. The degree of polymerization was determined by a viscometric method. The best results were achieved with a refining degree of 85 °C at the campfire of technical hemp — the degree of polymerization is 55, the bulk density is 0,316 g/ml, wheat straw is 95 and 0,239 g/ml, respectively. Thus, the possibility of obtaining microcrystalline cellulose from agricultural waste (bonfires of industrial hemp and wheat straw) with preliminary prehydrolysis refining in a semi-industrial disc mill is shown.

The article considers the dynamics of changes in internal stresses in composite materials during the process of flat hot pressing, and describes the key factors affecting the strength characteristics of the press composite, such as temperature, humidity, vapor-gas mixture pressure and the degree of curing of the binder. A detailed analysis of layer-by-layer briquette formation is presented, taking into account for each layer the elastic resistance, vapour-gas mixture pressure and degree of binder curing. It is established that the tensile strength perpendicular to the plate is a function of temperature, moisture content, density and degree of curing, and also depends on the layer coordinates and time. The effect of pressing pressure on the process is studied, including the risks associated with exceeding the permissible pressure, which can lead to wear of the spacers and deterioration of the conditions for the release of the formed vapor-gas mixture. Completion of the pressing process is determined by the moment when the strength of the adhesive joint in the weakest section becomes equal to or exceeds the internal stresses. For successful modeling of the process, it is necessary to take into account the law of loading, pressure and temperature fields, as well as the density (porosity) distribution in the briquette. The proposed mathematical model of the processes occurring during hot pressing of composite materials with specific boundary conditions allows one to develop, on its basis, engineering calculation methods and practical recommendations for the selection of rational technological pressing modes and press compositions for obtaining materials with predetermined properties. However, further experimental studies are necessary to clarify the coefficients and dependencies included in the closing relations. This work contributes to a better understanding of the processes of heat and mass transfer occurring during pressing in capillary-porous composite materials and their relationship with mechanical properties, which is important for optimizing hot pressing technologies and improving the quality of final products.