Root morphology and kinetics of Zn absorption by roots of common bean influenced by Zn status of the root environment1

Abstract

Understanding the kinetics of Zn absorption by roots and its effect on morphology of this organ is relevant for improving crop management, but still poorly studied for common beans. Therefore, an experiment was conducted in a hydroponic system with five initial concentrations of Zn (CZnI): 0.0; 1.0; 4.0; 16.0 and 48.0 μmol L-1. The experiment was installed with plants at V3 stage of development and aliquots of the solution collected over 24 h. The maximum absorption rate (Vmax), Michaelis-Menten constant (Km) and the absorption power (a) increased as a function of CZnI. The minimum concentration of Zn estimated for its absorption (Cmin) was at 0.0028 mg L-1. The influx of Zn (Imax) was higher in higher CZnI, 16,0 μmol L-1. Root length, root volume, root Zn content and Zn absorption efficiency increased with the increase of CZnI. Therefore, the increase of CZnI positively influenced kinetic parameters of root Zn absorption and common bean root morphology, characteristics that favor Zn absorption by roots and improves overall plant nutrition, favoring agronomical biofortification practices for Zn and other nutrients.