Features of Cu, Zn, and Mn accumulation in winter wheat grain depending on cultivation practices in the Northern Steppe of Ukraine

Abstract

This study presents a comprehensive assessment of how different agronomic practices — specifically, crop rotation (black fallow vs. silage corn) and fertilization systems (control, organic, mineral, and organo-mineral) — influence the accumulation of copper (Cu), zinc (Zn), and manganese (Mn) in winter wheat (Triticum aestivum L.) grain under the ecological conditions of the Northern Steppe of Ukraine. The findings demonstrate that agronomic interventions can serve as effective tools for modulating the micronutrient composition of cereal grain. By adjusting technological variables, it is possible to purposefully regulate the levels of essential trace elements in wheat grain — a factor of growing significance not only for yield optimization but also for enhancing the nutritional quality of the harvest. The research conducted on ordinary low-humus light clay chernozem (Calcic Chernozem) within a grain-fallow-row crop rotation system over four complete cycles (2013–2019) as a part of a long-term field experiment at the Rozivka Research Station of The Institute of Grain Crops of the National Academy of Agrarian Sciences of Ukraine. The results indicate that the accumulation of Cu and Zn in high-yielding winter wheat cultivars strongly influenced by the combination of environmental and agronomic factors, whereas Mn content appears to be less sensitive to these variables. A strong correlation was found between the micronutrient profile of wheat grain and key cultivation parameters — particularly the preceding crop and the fertilization regime. When winter wheat followed black fallow, the Cu content in the grain was 20 % lower compared to wheat sown after silage corn under both the control and organic fertilizer treatments. However, the application of mineral or organo-mineral fertilizers effectively mitigated the preceding crop effect on Cu levels. Fertilization, regardless of crop predecessor, consistently led to a statistically significant decrease in Zn content (by 20–24 %) and an increase in Mn content (by 5–7 %) relative to the control. Notably, for every 1000 kg increase in yield, grain Zn concentration declined by an average of 1.49 mg/kg. The formation of high yields on ordinary chernozem soils, which are inherently low in copper and zinc, is thus accompanied by a depletion of these elements in grain, while Mn levels tend to remain within the average range.