Formation of soybean seed quality depending on plant protection in the forest-steppe of Ukraine

The aim of the study was to establish the patterns of formation of soybean seed productivity and quality depending on weather conditions and varietal characteristics in the Right-Bank Forest-Steppe of Ukraine. Field studies were conducted during 2023-2025 on experimental plots in the Uman district of the Cherkasy region. The object of the research was five soybean varieties of different genetic origin and morphobiological characteristics: Gallek, ES Mentor, OAC Brook, Sigalia, and Kobza. The soil and climatic conditions during the years of research differed significantly in terms of temperature and moisture supply, which made it possible to assess the adaptive potential of varieties under contrasting hydrothermal conditions. Methodologically, the research was based on a field experiment taking into account the main elements of the yield structure, the weight of 1,000 seeds, the fractional composition of the seeds and quality indicators. The protein and oil content in the seeds was determined by infrared spectroscopy, and the moisture content was determined by a standard laboratory method. The dynamics of above-ground biomass formation were analysed using the sum of effective temperatures and a logistic growth model. It was found that in 2024, under conditions of moisture deficiency and elevated temperatures, the rate of biomass growth, 1,000-seed weight, and yield decreased by 8-25% compared to 2023 and 2025. According to the average three-year data, the highest and most stable yields were formed by the ES Mentor and Kobza varieties, while the Gallek and Sigalia varieties were more sensitive to stressful conditions. Seed quality indicators were mainly determined by variety: the Gallek variety was distinguished by the highest weight of 1,000 seeds and a high proportion of large seeds, while the protein and oil content remained relatively stable throughout the years of research. The practical value of the work lies in substantiating the feasibility of selecting soybean varieties with high ecological plasticity and stable seed quality for the conditions of the Right-Bank Forest-Steppe of Ukraine in the context of increasing climate variability