Efficiency of foliar fertilization and biostimulation systems in winter wheat crops of the Northern Steppe of Ukraine

Abstract

Abstract. Summarizing the research results, it is argued that under increasing aridity and high climatic volatility, traditional soil fertilization strategies for winter wheat are no longer sufficient for stable productivity. Foliar application of modern growth stimulators and chelated micronutrients during the flag leaf stage (BBCH 37–39) has been established as a critical technological measure. This approach mitigated abiotic stress and ensured a yield increase of 8.0–24.1% compared with the control. The use of amino acid complexes and multicomponent biostimulants significantly intensifies morphogenesis and forms a robust photosynthetic apparatus. In particular, the Amino Xerion preparation demonstrated the most pronounced effect on plant architecture, resulting in an 11.6% increase in plant height (up to 103.1 cm) and an 11.7% increase in productive stem density (up to 460 pcs/m²). This creates a reliable physiological foundation for active grain filling even under moisture deficit. Foliar nutrient correction directly transforms the yield structure by optimizing source-sink relationships and ensuring efficient retranslocation of substances to reproductive organs. Due to the antistress action of free L-amino acids and the synergism of micronutrients (Zn, B), ear length in the best variants increased by 14.6–18.3%, and 1,000-kernel weight reached 46.2–46.8 g (9.7–11.2% higher than the control). This is explained by the ability of exogenous amino acids to act as osmoprotectants, maintaining turgor and enzymatic activity during critical organogenesis. The reliability of these results is confirmed by ANOVA and Bonferroni post-hoc tests. Statistical verification identified a group of leaders in grain productivity: Amino Xerion (4.37 t/ha), Expert Grow (4.31 t/ha), and Calma (4.28 t/ha), which significantly exceed both the control and standard humate-based schemes. For practical implementation in arid regions, the integration of Amino Xerion (0.5 kg/ha) is justified as the most adaptive antistress agent. The use of the retardant Calma (0.4 L/ha) is also promising; by optimizing plant architecture and shortening the straw, it ensures high ear productivity and lodging resistance. The data indicate that combining micronutrients with biostimulation at a hydrothermal coefficient of 0.7–0.8 is a key tool for realizing the genetic potential of modern winter wheat varieties.