Мodern methods of determining stress and its impact on soybean productivity in the conditions of the Left-Bank Forest-Steppe of Ukraine

Abstract

Rationale for choosing the research topic. Soybean (Glycine max L.) is the most important global oil crop and high-protein grain-feeding crop. The soybean industry has three attributes of economy, politics and society at the same time, and is of great importance to the national food security, economic growth and social stability, as well as strategic significance. Soybean is a leguminous plant native to East Asia and China, and widely cultivated across the globe. The outcomes of the research conducted by the international scientific community on the effects of different stresses on plant physiological processes and productivity have been summarized. The analysis and summary of modern Glycine max L. cultivation technology, especially the use of nutritional systems and plant growth regulators (PGR) have been made. With the impact of climate change and environmental factors, the use of plant growth regulators (PGRs) has proven to be an important reserve for stabilizing crop development and improving crop yields, especially in Glycine max L. With modern changes in climatic conditions and intensification of agricultural production, the impact of stress conditions on plant growth and development has increased dramatically. Therefore, there is an obvious need to develop modern methods for determining stress factors using the global developments. Studying the nature of stresses and developing the ways of their reduction will ensure the realization of the biological potential of agricultural crops. To increase the stability of soybean yields, it is essential to use in its entirety modern technology, such as varietal selection taking into account the agroclimatic characteristics of the region and the use of growth regulators with anti-stress action. These physiologically active compounds contribute to more effective mobilization and utilization of mobile forms of mineral elements, increasing the overall resistance of plants to biotic and abiotic stresses, which makes research in this area relevant. It should be noted that the study of the mechanism of influence of salinity and growth regulators in a controlled environment on biochemical processes and morphological indicators has not been carried out, which makes this research to be of current concern. Therefore, the selected topic is important and of great current interest, since it has a comprehensive laboratory-field approach and has not been studied in the conditions of the Left-Bank Forest-Steppe. Connection of the work with scientific programs, plans, topics. The research was carried out according to the objectives outlined in the thematic plans and within the state scientific topics of Sumy National Agrarian University -“Features of the Formation of the Productivity of Leguminous Crops in the Conditions of the Forest-Steppe and Steppe of Ukraine”, (No. 0117U006536, 2017–2022) and “Development of Modern Methods for Identifying Stress in Agricultural Crops and Ways of Its Reduction” (No. 0121U113642, 2021-2025). Goal of the research is to determine stress and its impact on the growth and development of soybean, both in a controlled environment and in the field conditions of the Left-Bank Forest-Steppe of Ukraine. In the climatic chamber, the basis is the determination of the dynamics of the content of basic compounds as indicators of stress conditions and the stabilizing effect of growth regulators. In the field conditions, this is the analysis of morphological parameters to determine the influence of growth regulators on the reduction of stress factors and the realization of the biological potential of modern soybean varieties. To solve the goal, the following objectives were set: - To reveal the physiological reaction of Glycine max L. and the influence of growth regulators on the germination process under artificially created salt stress (in a controlled environment, PRC). - To determine the varietal features of the formation of morphological parameters of Glycine max L. under the use of growth regulators with anti-stress effect; - To establish the influence of growth regulators with anti-stress effect on the productivity and yield of soybean varieties; - To determine the quality indicators and biochemical analysis of soybean grain depending on the variety and growth regulators with anti-stress effect. - To calculate the economic and energy efficiency of the use of growth regulators for growing soybeans in the conditions of the Left-Bank Forest-Steppe of Ukraine. Object of the research is to evaluate the adaptability of soybean seedlings to salt stress under artificial conditions and the effects of growth regulators. The response of soybeans depends on variety characteristics, growth regulators, and weather conditions. Subject of the research is Glycine max L., determining stress, types of plant growth regulators, artificial conditions, abiotic stress (salinity), weather conditions, yield composition, and cultivation techniques, as well as the economic and energy efficiency of planting soybean growth regulators in the Left-Bank Forest Steppe of Ukraine and an artificial climatic chamber at the Henan Institute of Science and Technology, Xinxiang, China. Scientific novelty of the outcomes obtained. For the first time, the enzymatic activity and the mechanism of morphological adaptation of Glycine max L. seedlings under the artificially created salinity conditions (0, 50, 75, and 100 mM NaCl) have been investigated. The comprehensive research has been firstly conducted to study the influence of regulators on the growth and development of Glycine max. under the climatic chamber and field conditions. The varietal (Amadea, Aurelina, Bettina, Mentor, Navigator) features of soybean productivity formation when using growth regulators in the conditions of the Forest-Steppe of Ukraine have been identified. The technology of soybean cultivation for the conditions of the Forest-Steppe of Ukraine has been optimized. The issue of the influence of weather and stress conditions on the characteristics of growth, development and productivity depending on the variety and the use of growth regulators for foliar application has been further developed. The economic and energy efficiency of growing soybean varieties using growth regulators has been substantiated. Practical significance of the outcomes obtained. The main components of the research were verified in the conditions of the Left-Bank Forest-Steppe of Ukraine, in particular, on the lands of the following farms: SLK-11 (Sumy Region) and Rodina (Poltava Region) on an area of 42 hectares. The soybean growing technology, which has ensured grain yields of 2.89 and 2.91 t/ha, respectively, is recommended for production. Its effectiveness has been confirmed as follows: conditional net profit – 24. 928 and 25. 534 UAH/ha; production profitability – 140.2 and 146.7%, respectively. Research methods. In the process of conducting the research, a complex of general scientific and special methods was used. In artificial environmental chamber, leaves were treated with 100mg/L concentration of glycine betaine (GB) and Amino VG ANTISRESS at a concentration of 250 ml/h, once daily, twice. Samples were taken when the seedlings grew three leaves and one needle, with three-time repetition for each group. CK is the control group, Amino VG ANTISRESS and glycine betaine (GB) are the experimental groups. The physiological indicators in artificial climate chamber include chlorophyll content, enzyme activity (SOD, CAT, APX), malondialdehyde, and relative conductivity. The visual method was used to conduct phenological observations of the main phases of growth and development of soybean plants. The measuring and weighing method was used to determine biometric indicators, in particular plant height, leaf surface area, number and mass of beans, mass of seeds from one plant (individual productivity), as well as soybean yield. The chemical methods were used to determine the chlorophyll content and seed quality indicators, in particular protein and fat content. The mathematical and statistical method involved conducting a variance analysis to assess the reliability of the results obtained. The calculation and comparative method was used to determine the economic and energy efficiency of the use of mineral fertilizers and foliar feeding in soybean crops. Scientific outcomes. The thesis provides for a theoretical generalization and resolution of the scientific task concerning the study of modern methods for determining stress and its impact on the growth and development of soybean plants, both in controlled environments and under the field conditions of the Left-Bank Forest-Steppe of Ukraine. The study is based on examining the variety-specific characteristics of soybean productivity formation when applying various growth regulators with anti-stress effects. The results obtained from the research conducted between 2021 and 2023 enable to make the following conclusions. The research outcomes and their novelty consist in a comprehensive study of the influence of stress factors on the growth and development of Glycine max. The vegetative (in the climatic chamber) studies were conducted at the Henan Institute of Science and Technology (PRC) and field studies were conducted at the educational and scientific complex of Sumy National Agrarian University (Ukraine). The stress conditions (increased salinity) were modeled, and the effect of growth regulators with anti-stress action was studied. The dynamics of the content of basic compounds as indicators of stress conditions was determined. The influence of growth regulators on the reduction of stress factors and the realization of the biological potential of modern soybean varieties was revealed. It has been established that the north-eastern Forest-Steppe zone of Ukraine is favorable for growing soybeans. According to the analysis of weather conditions, the years studied were excellent in terms of meteorological parameters, which made it possible to detect the realization of the biological potential of soybeans. The driest conditions were in 2023, as evidenced by GTK = 1.19. The normal humidity was 2021 (GTC=1.23). The year 2022 was humid, confirming the calculated GTC=1.44. The research was conducted in an artificial climatic chamber at the Henan Institute of Science and Technology, Xinxiang, China. The Amino VG-Antistress regulator was evaluated for its ability to improve the salt tolerance of the Zheng 196 soybean variety at the seedling stage. The regulator enhanced the antioxidant capacity of Zheng 196 soybean seedlings and mitigated the effects of salt stress. The effect was most pronounced at a salt concentration of 100 mmol/L, confirming the regulator’s ability to improve soybean salt resistance. According to the climatic chamber research under the salt concentrations of 50 mmol/L, 75 mmol/L, and 100 mmol/L, the activities of superoxide dismutase, ascorbate peroxidase, and catalase all increased. At a salt concentration of 100 mmol/L, superoxide dismutase activity increased by 5.78%, though this increase was not effect of a growth regulator significant. In contrast, ascorbate peroxidase and catalase activities showed significant increases of 30% and 35.96%, respectively, at the same salt concentration, while malondialdehyde content notably decreased by 33%. This demonstrated that under high salt concentrations, the regulator significantly enhanced the antioxidant capacity of soybean seedlings and reduced membrane oxidation. The main compounds (enzymes) that are the indicators of resistance of plant organisms to increased salinity were studied. The key findings demonstrated the effectiveness of the regulator and highlighted its potential for increasing resistance. Along with this, the results are relevant for scientists seeking to develop substances with similar compositions to create newer, more effective growth regulators with anti-stress properties. The results offer additional evidence supporting the physiological role of melatonin and provide a theoretical foundation for its application in enhancing salt tolerance in agricultural practices. These findings are crucial for advancing the development of new growth regulators and provide scientific evidence supporting their feasibility in addressing the growing challenge of soil salinity. The field research results revealed that the main plant morphology and productivity parameters (height, leaf area) varied significantly depending on weather conditions, variety characteristics, and growth regulator application. The Bettina variety achieved the greatest height (71.4 cm), while the Aurelina variety exhibited the highest chlorophyll content (2.46 mg/g fresh weight) and leaf area (36.3 m²/ha). Application of the Antistress preparation yielded the highest values for all morphological parameters. Another important indicator of crop structure is the mass and quantity of seeds from one plant. The highest productivity indicators were achieved in 2023: seed count (32.1 pieces); individual productivity (6.26 g). Among the varieties, Navigator produced the highest seed count (32.0 pieces), while Aurelia yielded the highest seed mass (5.63 g). The application of the growth regulator Sugar Mover resulted in the highest seed count (31.6 pieces), while Antistress achieved the highest individual plant productivity. The average highest yield indicator under the conditions of 2023 was 3.23 t/ha. The leader was the variety Aurelina (2.90 t/ha). The highest yield (2.91 t/ha) was achieved at the level of applying the Antistress preparation. The conditions of 2023 were the most favorable for forming a 1000-grain weight of 194.8 g. The variety Bettina formed the largest 1000-grain weight at 189.3 g. The application of growth regulators, including Amino VG Antistress, significantly increased this indicator (185.2 g). It was established that both the genetic potential of the variety and agronomic techniques influence the chemical composition of soybean grain. The highest protein content (42.0%) was recorded in the Aureliana variety with the application of Sugar Mover, while the highest fat content (19.5%) was observed in the Mentor variety under control conditions, indicating an inverse relationship between protein and fat content under the influence of growth regulators. Biochemical analysis results showed the highest levels of both essential and non-essential amino acids in the Mentor variety with the use of Sugar Mover, demonstrating the high effectiveness of this combination for enhancing the biological value of the grain. The economic calculations revealed that the highest profitability level of 161% was achieved by cultivating the Aurelia soybean variety under control conditions. The maximum conditional net profit per unit area (27,228 UAH/ha) was obtained by growing the Aurelia soybean variety and applying the stress-protective growth regulator Antistress. The highest average energy efficiency coefficients were achieved by cultivating the Aurelia soybean variety and applying the stress-protective growth regulator Antistress (Кее 3.33).