Exploring the impact of copper excess on soybean genotypes: insights from root morphology and plant ionome

Global growing demand for food production and commodity increased prices stimulate soybean cultivation in Brazil even in areas with high soil copper (Cu) concentration. This can promote root injuries and nutritional imbalances, reducing the growth and yield of Cu-sensitive soybean genotypes. The study aimed to investigate soybean genotypes potentially adapted to Cu-contaminated zones. Four soybean genotypes (NA 5909, DM 5958, M 6410, and DM 6563) and three Cu concentrations in the nutrient solution (0.03, 1.2, and 2.4 mg L⁻¹) were evaluated. Root and shoot dry mass, root morphology, and inorganic composition of plant tissues were determined. The shoot and root dry mass was affected by Cu excess, especially in DM 5958 genotype, which decreased by up to 46%. Otherwise, the DM 6563 genotype stood out for growing satisfactorily under Cu excess and keeping significant amounts of Cu in the belowground biomass. The Cu excess promoted root thickening and shortening, and altered the ionome of soybean plants by decreasing the concentrations of K, Ca, Mg, and Fe, yet increasing P and N, which caused decreased plant growth. Finally, our outcomes indicated DM 6563 genotype exhibits promising traits for Cu phytostabilization, making it preferable for cultivation in Cu-contaminated areas.