Bulletin of Sumy National Agrarian University. The series: Agronomy and Biology

INFLUENCE OF ENVIRONMENTAL CONDITIONS ON SEED PRODUCTIVITY OF ASPARAGUS COWPEA VARIETIES (VIGNA UNGUICULATA (L.) WALP. SUBSP. SESQUIPEDALIS (L.) VERDC.)

I. M. Bоbоs, O. O. Kоmаr, A. P. Ivanytska — Wed, 23 Oct 2024 00:00:00 +0300

For the first time in the rainfed conditions of the Kyiv region, a study was conducted on the effect of plant density on the seed productivity of cowpea asparagus, which will improve the technology of growing the crop and expand the species diversity of leguminous vegetable plants. The main methods of studying this problem are field – to identify the interaction of the object of study with biotic and abiotic factors of the northern part of the Forest-Steppe of Ukraine, statistical – to assess the reliability of the results. Plant density of vegetable cowpea varieties influenced the duration of interphase periods. Unequal growing conditions in cenosis of different densities are expressed by the duration of the growing season. With an increase in plant density, the duration of the period from mass germination to the onset of technical maturity decreased. This pattern was characteristic of all phases of growth and development of vegetable cowpea plants. The earliest ripening varieties were U-tia-Kontou and Kafedralna with thickened crops (143 thousand units/ha) with the shortest duration of the growing season of 135–141 days. On average, during the studied years, the sum of effective air temperatures (> 10 °C) during the growing season of cowpea varieties ranged from 938 to 1114 °C, and the amount of precipitation, respectively, from 125 to 136 mm. Within the studied variants, a direct strong correlation was found between the yield of cowpea varieties grown at different plant densities and the sum of effective temperatures (r = from 0.72 to 0.94) and precipitation (r = from 0.66 to 0.77). An increase in the sum of effective temperatures by 1 °C leads to an increase in seed yield by 0.8-0.9 kg/ha, and an increase in precipitation by 1 mm leads to an increase in seed yield by 3.0-9.0 kg/ha. The sowing scheme of 70 x 25 cm proved to be optimal for both cowpea varieties under the studied conditions. Due to the optimal growth conditions, cowpea grown at a density of 57 thousand units/ha has a high productivity of one plant (30–30.3 g/plant) and a weight of 1000 seeds (186–190 g). The results also indicate significant differences between cowpea varieties in terms of agronomic traits and seed quality. The best adaptive cowpea variety in the northern part of the Forest-Steppe of Ukraine was Kafedralna.

PLANT HEIGHT IN SYNTHETIC POPULATIONS OF WINTER RYE IN THE CONDITIONS OF THE NORTHERN FOREST STEPPE OF UKRAINE

O. I. Bunyak, S. V. Shovkun — Wed, 23 Oct 2024 00:00:00 +0300

IMPROVEMENT OF SOIL FERTILITY THROUGH THE CULTIVATION OF LEGUMINOUS CROPS

V. V. Hamyunova, V. M. Yermolaiev — Wed, 23 Oct 2024 00:00:00 +0300

The aim of the research was to restore soil fertility, enrich it with fresh organic matter and biological nitrogen through the cultivation of leguminous crops, particularly peas. In the current conditions of farming, when the economy of farms is vulnerable and weakened, this issue is relevant. The research identified the impact of pre-sowing seed treatment and plant nutrition optimization on improving the state of southern chernozem. The studies were conducted at the Experimental Field of the Educational-Scientific-Practical Center of MNAU during 2021-2023 using standard methodologies. Peas of the Madonna variety were grown on southern chernozem. The effectiveness of seed treatment before sowing, application of a starter dose of N15P15K15 fertilizers, and foliar feeding of plants were determined. It was found that conservation measures – pre-sowing seed treatment and nutrition optimization – positively affected the increase in grain productivity of peas. Maximum grain yield levels were achieved through a combination of seed treatment, fertilizer application, and foliar feeding. As a result of the research, it was revealed that these technology elements significantly increased the aboveground biomass of pea plants. The amount of biomass during the pre-harvest period significantly increased under the influence of resource-saving nutrition optimization compared to the control variant. Seed treatment alone led to a 10.4% increase in accumulated dry matter, while the combination of researched measures resulted in an even more significant growth – up to a maximum of 58.5% compared to the control. The most biomass was formed in variants where seed treatment, N15P15K15 application, and foliar feeding with Nanovit at a dose of 1 L/ha were combined. A close correlation dependence between grain yield levels and accumulated biomass remaining in the soil as fresh organic matter was determined. The total number of nodules throughout the period was significantly higher than active ones. This may be due to high temperature regimes and not always optimal soil moisture supply for their effective work. With symbiotically fixed nitrogen and its content in aboveground biomass, soil nitrogen can increase from 73.2 to 110.0 kg/ha. Its growth compared to the control variant ranged from 19.7 to 60.3%. This is an extremely important feature for free enrichment of soil with biological nitrogen, valuable fresh organic matter, and an overall positive impact on key fertility indicators.

RUDERAL VEGETATION OF THE DANUBE BIOSPHERE RESERVE OF THE NATIONAL ACADEMY OF SCIENCES OF UKRAINE AND MEASURES OF ITS RESTRUCTURING OPTIMIZATION

Wed, 23 Oct 2024 00:00:00 +0300

The ruderal vegetation of the nature reserves, especially areas outside of absolute reserve zones, is a source of alien species that lead to the transformation of natural vegetation. The habitats across of the Danube Biosphere Reserve, which are in the stages of intensive formation, are characterized by successful development of ruderal communities. These processes are also facilitated by the excessive transformation of geocomplexes, in particular in the buffer zone and the zone of anthropogenic landscapes as a result of large-scale hydraulic engineering construction, and the transformation of the large areas in the estuary zone into agricultural land, quarry sand mining (Zhebriyansk coastal ridge), grazing, reed mowing in industrial extend, burning, reforestation (Zhebriyansk coastal ridge), recreation, pollution of the aquatic and terrestrial environment, etc. Based on the phytosociological studies of 1998–2021 and the analysis of the authors' vegetation plots using the modified TWINSPAN algorithm, the syntaxonomy of the ruderal vegetation of the Danube Biosphere Reserve was clarified and measures for constructive optimization of its territories were proposed. The distribution of the 25 vegetation associations and 5 unranked communities belonging to 6 phytosociological classes (Stellarietea mediae, Artemisietea vulgaris, Polygono-Poetea annuae, Galio-Urticetea, Bidentetea, Robinietea) was established. The main natural and anthropogenic factors for the ruderal vegetation formation are the type and extend of soil disturbance. The landscape geomorphology, soil composition, moisture and light conditions also have prominent impact. The peculiarities of the coenofloras of studied vegetation are high proportion of neophytes and considerable representation of native species of a broad ecological range. The proposed measures for the restructurisation of the ruderal vegetation included considering the most recent anthropogenic transformations (military changes, functioning of the grain corridor, the extension of rewilding, etc.). The results of the studies will be the scientific basis for monitoring and managing of disturbed ecosystems, improving the effectiveness of measures to restore and optimize natural vegetation.

RAPD-ANALYSIS IN THE SYSTEM OF COMPLEX ECOLOGICAL AND ANALYTICAL MONITORING OF RED CLOVER POPULATIONS OF MEADOW GRASS PHYTOCOENOSIS OF THE SUMY REGION

K.S. Kyrylchuk, O.M. Bakumenko, I. V. Vereshchahin — Wed, 23 Oct 2024 00:00:00 +0300

The article is devoted to the study of populations of red clover (Trifolium pratense L.) in natural herbaceous phytocoenoses in Sumy city and Sumy region (Nature Reserve Mykhailivska Tsilyna) using molecular biological methods, in particular PCR diagnostics with the participation of oligonucleotide RAPD primers, in order to establish the genetic diversity of the species at the population level. The study of the genetic structure of species populations is a component of a comprehensive population analysis, which, among other things, includes the study of age and ontogenetic, sexual, size and vitality structures, reproduction and growth processes, which allows us to reveal the mechanisms of species resistance in certain growth conditions, assess the prospects for its existence and draw conclusions about the genetic diversity of its populations. From an agronomic point of view, red clover is an extremely valuable field crop, as it is used as fodder for livestock, and its ability to fix atmospheric nitrogen in the soil provides companion grasses with this nutrient. For this reason, meadow clover is a good precursor for cereals. Within natural phytocoenoses, the share of meadow clover can be up to 20% of the grass stand, which, together with other grass species, forms highly productive meadows. The study of natural communities of red clover at the molecular (genomic) level allows us to assess the degree of biodiversity of the species, the breeding potential of varieties as a source of target genes for selection in particular and genetic plasma in general. Molecular analysis will also make it possible to estimate the loss of genetic resources of the red clover as a result of aggressive military operations. The object of the study was red clover samples collected in different locations of herbaceous phytocoenoses in Sumy and the Nature Reserve Mykhailivska Tsilyna. Genetic material (DNA) was extracted using salt-enzyme extraction, followed by purification and nucleic acid precipitation. DNA amplification was performed using RAPD primers Ver_1 AATCGGGCTG and Ver_2 GTTGCGATCC followed by visualization of reaction products in an agarose gel in the presence of ethidium bromide. The nature of the amplicons indicates the satisfactory quality of the nucleic acid preparations. Amplification of fragments revealed a high degree of polymorphism at both markers (17 polymorphic loci out of 18), and the study of the affinity of red clover samples using cluster analysis established a close relationship between samples growing within the city of Sumy in adjacent locations, as well as the Nature Reserve Mykhailivska Tsilyna.

ASSESSMENT OF THE POPULATION STATUS OF THE REGIONALLY RARE PLANT SPECIES ANEMONE SYLVESTRIS IN THE URBAN ENVIRONMENT (SUMY)

I. M. Klymenko, D. O. Leshchenko, H. O. Klymenko, V. V. Tymoshchuk — Wed, 23 Oct 2024 00:00:00 +0300

In an era of global urban expansion, an important aspect of biodiversity conservation is to understand the impact of urbanisation on it, as a number of anthropogenic factors, including habitat change and the introduction of new species, directly affect the status of native species and their gene pool. A separate aspect is the uncontrolled spread of invasive species, which not only negatively affects native species and natural ecosystems, but also causes significant economic losses and threatens human health. In addition, residential and commercial development has a significant destructive impact on the local biodiversity of cities. In order to ensure appropriate conditions for the existence, growth and development of local biodiversity, it is necessary to develop a system of nature reserves in the urban environment. It is the NRF objects that contain the appropriate territory regime, which allows to ensure the preservation of landscape components and biodiversity in their natural state. In view of the above, studies of populations of rare plant species within cities, including Sumy, are relevant to ensure further expansion of the existing network of protected areas. The state of the population of the regionally rare species Anemone sylvestris within the urbanised habitat (Sumy) was assessed. The area of the population field covered a plot of 7 x 8 m. The average density of flowering individuals was 14.3 plants per 50 cm2. A maximum of 37 flowering plants were recorded on the plot. The nature of the plant distribution within the population field is contagious. Morphometric analysis showed that the plants had rather long flowering shoots, which reached a maximum of 49 cm, and were on average 43 cm high. Plants had 4 to 6 leaves on tall petioles (8.6 to 18.4 cm). Leaf length and width were 4.3 and 7.5 cm, respectively. The vital status of each Anemone sylvestris plant included in the sample showed that all plants belonged to the highest vital status, and their quality index (Q) ranged from 0.71 to 0.98. All the examined Anemone sylvestris specimens exceeded the limit of 0.66 in terms of their vitality and, accordingly, were classified as having the highest vitality value. According to the results of the integrated assessment of the population's vitality, it was found that in 2023 this population had the highest level of vitality, equal to 0.5.

USE OF AGRICULTURAL TECHNOLOGIES TO PRESERVE SOIL RESOURCES AND IMPROVE SOIL QUALITY

V. P. Reznichenko, L. V. Kolomiiets, I. V. Сherednychenko — Wed, 23 Oct 2024 00:00:00 +0300

The article examines the main causes of soil degradation, including erosion, depletion and pollution. It was determined that soil depletion occurs as a result of intensive use of land without proper restoration of its fertility. Continuous cultivation of monocultures, excessive use of chemical fertilizers and pesticides lead to a decrease in the content of organic substances in the soil, deterioration of its structure and a decrease in the ability to retain moisture, which makes the soil less productive and vulnerable to erosion. It is highlighted that soil pollution is the result of anthropogenic activities, such as industrial production, improper storage of waste, excessive use of chemicals and pesticides. Soil degradation leads to a decrease in its fertility, which, in turn, affects the yield of agricultural crops. Plants do not receive enough nutrients, which leads to their weak growth and development. In addition, degraded soils are less able to retain moisture, which is especially critical in conditions of climate change and frequent droughts. This forces farmers to spend more on irrigation, fertilizers and pesticides, which increases the cost of production and reduces the economic efficiency of agriculture. The article substantiates a number of leading technologies for preserving soil resources and improving soil quality. Conservation tillage methods, including minimum and zero tillage, have become an important part of modern agriculture. Minimal tillage involves reducing the amount of soil tillage, which reduces the mechanical impact on it, helps to preserve plant residues, increase the content of organic substances and conserve moisture. Zero tillage involves the complete rejection of mechanical tillage, which allows preserving the natural structure of the soil, improving its water and air permeability, increasing the number of beneficial microorganisms and reducing greenhouse gas emissions. The article also discusses the implementation of crop rotation and cover crops as effective methods of preserving soil resources and improving soil quality. Crop rotation helps improve soil structure, reduce the risk of erosion, control pests and diseases, and ensure a balanced use of nutrients. Cover crops create a protective layer on the surface of the soil, improve its structure, enrich the soil with organic substances and help retain moisture. The implementation of these technologies allows to ensure the sustainable development of agriculture, increase the efficiency of the agricultural sector and reduce the negative impact on the environment.

THERMAL REGIMES OF PODZOLIC SOILS ON SLOPING AND PLAIN LOCATIONS

V. B. Solovei, E. A. Trotsenko — Wed, 23 Oct 2024 00:00:00 +0300

The article reflects research on the hydrot hermal conditions conducted in various agricultural regions aimed at assessing the influence of these parameters on crop yield and the quality of agricultural products. The research results emphasize the importance of accounting for agroclimatic parameters in modern agriculture to adapt to changing conditions. It is indicated that the scientific research was conducted in the forest-steppe zone of the Kharkiv region. Monitoring of the temperature regime of dark gray and meadow podzolic soils was carried out at four different sites. The sites include two types of slope exposure: a gentle straight slope with a northwest exposure and a convex slope with a southeast exposure, as well as flat plakor territory and ravine bottom. The main goal of the research was to analyze the annual temperature dynamics of the soil to determine the features of the formation of the thermal regime of these soils under modern climate conditions. Research methods included the use of thermosensor technology implemented on the Arduino controller, which allowed measuring soil temperature at depths from the soil surface to 120 cm with a step of 10 cm and a 30-minute interval throughout the year. Information was transmitted via the GSM network, and data were stored on a specialized web server in real-time mode. It is noted that the research allowed evaluating changes in temperature regimes at the specified locations. The paper presents an analysis of temperature fluctuations during warm and cold periods of surface and deep soil layers in different relief conditions throughout the year. Observations were made on short-term freezes and the duration of periods with negative temperatures in different types of terrain. Special attention is paid to comparing minimum temperatures and the duration of freezes on northwest and southeast slopes, plakor, and ravine bottom. It is established that the lowest and highest temperatures and their fluctuations are recorded on the soil surface. The maximum depth of soil freezing is up to 30 cm on the northwest slope, and the frost period lasts 104 days. The minimum surface soil temperature does not always coincide with the lowest air temperature.

GROWTH OF THE SHOOTS OF ACER L. SPECIES IN THE INDUSTRIAL CITIES OF THE STEPPE ZONE OF UKRAINE

O. P. Suslova — Wed, 23 Oct 2024 00:00:00 +0300

Species of the genus Acer L. are widely used in the landscaping of industrial cities in the steppe zone of Ukraine. The research aimed to evaluate the morphometric parameters of vegetative organs and the intensity of stem growth. The objects of research were species of the genus Acer in the parks of industrial cities in the northern part of the Left Bank Steppe of Ukraine: A. platanoides L., A. pseudoplatanus L., A. saccharinum L., and A. tataricum L. The length of annual shoots was measured on ten branches of five 35-year-old model trees selected for each species studied. Measurements were made with a caliper (with an accuracy of 0.1 cm). The height growth of stems was measured using a Makarov pendulum altimeter (with an accuracy of 0.5 m). It was found that the length of annual shoots of maples in Pokrovsky Park varies from 10.03 cm in A. tataricum to 15.6 cm in A. saccharinum, and in Novogorodivsky Park – from 10.16 to 15.42 cm, respectively. The shoot length of trees in Pokrovsky Park is larger than in Novogrodivsky Park by 1 % in A. saccharinum, 2 % in A. platanoides, and 5 % in A. pseudoplatanus. The length of internodes on annual shoots was the largest for A. platanoides (8.35–10.8 cm), and the smallest – for A. tataricum (4.52–4.81 cm). In Novogrodivsky Park, the length of internodes exceeds the value in Pokrovsky Park by 4 % in A. pseudoplatanus, 5 % in A. saccharinum, and 6 % in A. tataricum. The internodes of A. platanoides in Pokrovsky Park are 23% longer than in Novogrodivsky Park. The differences in the length of shoots and internodes between the trees in the studied parks are not statistically confirmed. The largest annual height growth of stems was estimated in A. pseudoplatanus: 58.5 cm (Pokrovsky Park) and 55.8 cm (Novogrodivsky Park); the smallest – in A. tataricum: 22.0 cm and 21.3 cm, respectively. It was found that the difference in the annual height growth between the trees of the studied parks is not significant, except for A. platanoides (tobserved=2.25; t0.05=2.02). The culmination of the annual height increment of the studied trees occurs at the age of 30–40 years old, depending on the species and their growth rates. The results obtained should be taken into account when developing practical measures for the preservation, design and reconstruction of city parks for the most effective use of Acer species in them.

EFFICIENCY OF OILSEED RADISH IN REDUCING FIELD WEEDINESS DURING ITS INTERMEDIATE (SUMMER) GREEN MANURE USE

Ya. H. Tsytsyura — Wed, 23 Oct 2024 00:00:00 +0300

The expediency and efficiency of green manure farming systems in the variants of biological control of the level of weeds in the field using the variant of intermediate (summer) green manure was investigated and substantiated. In the ten-year research cycle (2014–2023), basic methodological approaches to assessing both the bioproductive potential of oilseed radish and international methods for assessing the overall level of weed infestation and the phytocoenological status of the recorded weed species were applied. The species structure of weeds in the oilseed radish agrocenosis was analysed and evaluated by such indicators as density (D), frequency of occurrence (F, %), abundance (Ab), relative density (RD, %), relative frequency of occurrence (RF, %), relative abundance (RAb, %), significance index (IVI), total dominance ratio (SDR), and frequency class of weed species (Fcl). The results of the aftereffect of flooded green manure on the quantitative and weight index of the level of weediness of a number of crops in accordance with the crop rotation scheme were evaluated. The efficiency of oilseed radish application in the variant of green manure for controlling both the species structure of the corresponding agrocenosis in the year of green manure and in the variant of technological aftereffect, especially on a row crop group, was established. In comparison with the control without green manure, a general decrease in the number of early spring weeds by 66.1% by number and 49.7% by weight, late spring weeds by 37.7% (39.5%), winter weeds by 72.2% (63.6%) and perennial weeds by 48.0% (46.8%), respectively, was observed. A general decrease in the phytocoenological status of the dominant weed species by 8.5–18.9% with a change in the species frequency class (Fcl) and a 23.7% reduction in the total dominance ratio (SDR) by one category was established. A close, reliable inverse relationship between the volume of aboveground biomass formed at the time of green manure ploughing and the number of weeds (r = -0.717, dxy = 51.4% at p < 0.001) and their weight (r = -0.677, dxy = 45.8% at p < 0.001) was proved. A similar relationship was found between the bioproductivity of oil radish in the year of green manure and its effect on subsequent crops with a level of determination of 54.4% for the number and 49.1% for the weight of weeds (at p<0.05). Based on the results obtained, oilseed radish is recommended as a highly productive and effective candidate in the system of summer (intermediate) green manure technologies for controlling the level of weediness in the field.

SEPARATE ASPECTS OF VARIATION OF BOTANICAL COMPOSITION IN FORMATION OF SOWN MEADOWS OF MOUNTAIN-FOREST BELT OF CARPATHIANS

S. S. Chepur — Wed, 23 Oct 2024 00:00:00 +0300

An important reserve for increasing fodder production is the sown meadows of an intensive type, which are created by accelerated grassing on slopes with a slight steepness, and which have been negatively affected by water erosion, and in crop rotations saturated with intensive row crops, by continuous sowing of fields vacated by them. The results of the research on the selection of legumes and cereal grasses for fodder productivity and economic efficiency for the creation of grass stands of sown meadows for long-term use in the conditions of the mountain and forest belt of the Carpathians are presented. Widespread in the region and valuable in terms of fodder were studied -Trifolium pratense, Lotus corniculatus, and Medicago sativa (which is not common here), were studied in their pure form and in a mixture with Phléum pratense. Research methods are field, laboratory, analytical and statistical. The paper presents data on the variability of the botanical composition of the harvest of sown meadows with increasing age and their influence on the quantitative and qualitative correlations of individual indicators of the grass stand, which correlate with the yield of perennial grasses. In the mountainous forest zone of the Carpathians, meadow clover has the highest yield (up to 915-941 c/ha of green mass for 2 mowings), the best quantitative and qualitative indicators, except for the yield of digestible protein per hectare, indicators of productivity, economic and energy efficiency in single-species sowing, but also the shortest life span (maximum 1.5-2 years for the vast majority of plants). Single- and two-species sowings of alfalfa and bird's foot trefoil are 15-27% inferior to meadow clover in terms of average annual main indicators of fodder productivity per hectare. However, they fall out of the grass stand more slowly, thus maintaining its high fodder productivity for longer. It was found that meadow timothy has a positive effect on legumes. In two-species crops with meadow timothy, in the second and third year after sowing, resistance to falling out in meadow clover increased by 4.2% and 16%, in alfalfa by 8.4% and 11.4%, respectively, compared to single-species crops. According to the results of the study, in the conditions of the mountain-forest belt of the Carpathians, with the aim of improving the feed balance and reducing the existing deficit of feed protein in the diets of animals, it is proposed to grow meadow clover in one-species or two-species crops with meadow timothy, in crop rotations with one-year use of grass, and alfalfa crops, horned larkspur in fodder rotations with longer use.

DEVELOPMENT OF BIOPHILIC DESIGN AS A METHOD OF INTEGRATING NATURE INTO URBAN PLANNING

T. D. Shyyan, N. I. Konshyna, I. P. Bodnar — Wed, 23 Oct 2024 00:00:00 +0300

The process of urbanization presents significant challenges for human comfort and ecological stability, and the lack of connection with nature leads to numerous negative consequences for the physical and mental health of the population. In turn, biophilic design emerges as a promising approach to integrating natural elements into the urban environment, fostering symbiotic relationships between humans and nature. This article examines the development of biophilic design as a method to improve urban planning by incorporating natural elements. The relevance of this research lies in addressing the need for developing sustainable development strategies for cities that prioritize the well-being of people and ecological balance. By applying biophilic principles, urban planners and architects can create environments that enhance the sense of connection with nature, thereby improving overall quality of life and mitigating the negative consequences of urbanization. The purpose of this article is to investigate the development of biophilic design principles and their application in the context of urban planning. Through a comprehensive review of literature and specific case studies, the article highlights various strategies and methods used in biophilic design to integrate nature into urban spaces. It also evaluates the effectiveness of these approaches in achieving stated goals, including enhancing aesthetics, air and water quality, reducing stress, and promoting biodiversity. The findings indicate that biophilic design offers numerous benefits for urban environments, including increased biodiversity, improved health and well-being of people, enhanced social cohesion, and increased resilience to climate change. At the same time, the integration of biophilic elements into urban planning has shown positive economic impacts by increasing property values and attracting investments. These results suggest that biophilic design holds immense potential as a holistic approach to urban planning, aligning human needs with ecological imperatives. However, further research is needed to examine the long-term effects of biophilic interventions on urban ecosystems and to develop standardized metrics for assessing their effectiveness. Future research should explore the scalability of biophilic design principles across different urban contexts and cultural circumstances, as well as their compatibility with other sustainable development strategies.

FORMATION AND FUNCTIONING OF THE ASSIMILATION APPARATUS OF SOYBEAN LINES ISOGENIC FOR E GENES UNDER DIFFERENT PHOTOPERIOD DURATIONS

Yu. Yu. Yuhno, O. O. Avksentieva, D.V. Glushach — Wed, 23 Oct 2024 00:00:00 +0300

Soybean (Glycine max (L.) Merr.) is a leading leguminous crop and at the same time a model plant for studying the biological nature of photoperiodism. The study of the role of genotype and photoperiodic reaction of plants in the formation of adaptive strategies for the regulation of assimilation processes is an urgent problem of modern phytophysiology. The paper presents the results of the analysis of the functioning of the assimilation apparatus according to the indicators of assimilation indices and the content of photosynthetic pigments in soybean lines that are isogenic for genes that control photoperiodic reaction under different photoperiod conditions. Near isogenic lines (NILs) for genes that control photoperiodic reaction of soybeans (Glycine max (L.) Merr.) were used as plant material: short-day plants (SDP) – variety Clark and isoline L80-5879 (genotype e1E2E3E4e5E7 and E1e2e3E4e5E7); neutral day plants (NDP) – isolines L63-3117 and L71-920 (genotype e1e2E3E4e5E7 and e1e2e3E4e5E7). From the stage of the third true leaf (V3), one part of the plants was grown under natural conditions (16 hours), and the second part was exposed to a short day (9 hours) for 14 days (phase of the fifth true leaf – V5). In the development phases V3 and V5, the dry weight of leaves and plants, the number and area of leaves were measured, on the basis of which the assimilation indices (LAR, SLA, LWR) were calculated and the content of chlorophylls A and B was analyzed. The results of the experiments showed that the presence of three dominant alleles of genes E2, E3 and E4 determines the shortday reaction of plants of the variety and under the influence of a photoperiod shortened to 9 hours causes a decrease in LAR, mainly due to a significant decrease in SLA and a less significant increase in the level of LWR, as well as a decrease in the content of chlorophylls relative to the level of these indicators according to long photoperiod. The dominant gene E1 caused a greater decrease in the content of chlorophylls A and B, as well as LAR and SLA during a short photoperiod, which can characterize the inhibition of the increase in the linear parameters of the plant and more efficient accumulation of dry mass, which is an important condition for the transition to the generative phase. The combination of dominant alleles of genes E3 and E4 determined a higher level of LAR under the influence of a short photoperiod mainly due to a more significant increase in LWR than a decrease in SLA. At the same time, the content of chlorophyll was not change, compared to a long day. The recessive state of genes е1, е2, е3 caused approximately the same indicators of chlorophyll content and LAR, with a slight difference in SLA and LWR on long and short days, which may indicate a sufficiently high adaptability of the assimilation apparatus of these plants to photoperiodic conditions. It was established that, depending on the allelic state of the photoperiodic sensitivity genes (E-series genes) in the soybean isolines genotype and their photoperiodic response, multidirectional strategies for adapting the assimilation apparatus to conditions of photoperiods of different durations are launched.