Influence of CuSO₄ application rates during the vegetative stage on agronomic characteristics of Glycine max (L.) Merrill

Several micronutrients are essential for the development of agriculturally important crops, including copper (Cu). This study aimed to evaluate the effects of different doses of copper sulfate (CuSO4), expressed as mg L-1 of elemental Cu, on early-maturing soybean during the vegetative phase. Plant parameters such as shoot and root length, fresh and dry biomass of shoots and roots, and Cu bioaccumulation (expressed in mg kg⁻¹) in roots and shoots were assessed. Eight Cu concentrations (0, 5, 15, 35, 85, 100, 125, and 600 mg L-1) were prepared and applied directly into the planting furrow. A precocious soybean cultivar was used. Measurements were taken during the vegetative stage. Significant differences were observed at 100 and 125 mg L-1 doses for root length and root dry mass. The highest Cu bioaccumulation in roots and shoots occurred at 125 mg L-1, while concentrations above this threshold showed toxicity to the early-maturing soybean cultivar. The Cu source applied at varying doses influenced only root development parameters—specifically root length and root dry mass—as well as Cu content accumulated in both roots and shoots during the vegetative growth stage.