Dose-Dependent Dual Effect of Soil Copper on the Initial Development of Glycine max (L.) Merr. cv. BRS 257 Seedlings

The aim of this study was to evaluate, through nonlinear regression models, the initial development of soybean (Glycine max L. Merr. cv. BRS 257) in soil supplemented with different copper levels. The experiment was performed in a greenhouse under natural light and temperature conditions. The seeds were sowed in soil containing different copper levels (11.20, 32.28, 52.31, 64.51, 79.42, 117.70, 133.53, 144.32, or 164.00 mg kg^- 1). Germination percentage was not affected by the increase of copper content in the soil, but there was a delay in the germination process. There was no influence of copper levels on the seedling emergence speed index until 98.42 mg kg^- 1; however, higher copper amounts reduced this parameter. Low copper concentrations increased plant development, but higher concentrations compromised mainly root growth. Overall, these results suggest that copper supplementation in the soil exerted dose-dependent dual effects on soybean seedlings.