Effects of plant growth regulators and micronutrient fertilizers on winter wheat productivity

Abstract

Winter wheat (Triticum aestivum L.) is one of the major cereal crops ensuring food security and sustainable grain production in Ukraine. However, increasing climatic variability, particularly frequent droughts and uneven precipitation distribution in the Northern Steppe of Ukraine, substantially limits the realization of the crop yield potential. Therefore, improving adaptive cultivation technologies through the use of modern plant growth regulators and micronutrient fertilizers has become an important direction of contemporary agronomic research. The objective of this study was to evaluate the influence of modern foliar-applied plant growth regulators and micronutrient fertilizers on biometric characteristics, yield components, and grain productivity of winter wheat under the environmental conditions of the Northern Steppe of Ukraine and to identify the most efficient product for practical agricultural application. Field experiments were carried out during 2024–2026 at the Educational and Research Center of Dnipro State Agrarian and Economic University on ordinary low-humus heavy loam chernozem. The experiment was established as a randomized complete block design with three replications. Ten experimental treatments, including an untreated control and nine commercial plant growth regulators and micronutrient fertilizers, were evaluated following foliar application at the flag leaf growth stage (BBCH 37–39). Plant height, productive stem density, spike length, thousand-kernel weight, and grain yield were determined according to standard field methodologies. Foliar application of the investigated products significantly improved plant growth and grain productivity throughout the three-year experimental period. The highest biometric characteristics were obtained following application of Amino Xerion, where plant height reached 111.3 cm, productive stem density measured 476 stems m², spike length reached 10.3 cm, and thousand-kernel weight increased to 48.8 g, substantially exceeding the untreated control. Grain yield responded positively to all foliar treatments despite considerable differences in weather conditions among years. Average grain productivity over the study period varied from 4.44 t/ha in the untreated control to 5.54 t/ha after Amino Xerion application, corresponding to a yield increase of 24.8%. High productivity was also recorded for Expert Grow (5.48 t/ha), Kalma (5.27 t/ha), and Scudero 6:25:25 (5.17 t/ha). The positive influence of these products was associated with improved crop growth, formation of a denser productive canopy, and better development of yield components. Statistical analysis confirmed significant differences between the highest-performing treatments and the untreated control in all experimental years. Modern amino acid-based plant growth regulators and complex micronutrient fertilizers effectively improve winter wheat productivity under the environmental conditions of the Northern Steppe of Ukraine. Among the evaluated products, Amino Xerion demonstrated the highest agronomic efficiency and may be recommended as an effective component of climate-adaptive winter wheat cultivation technologies aimed at improving grain yield stability under contrasting hydrothermal conditions.