Table II.

Kinetic parameters for low-affinity root Mn2+ influx in 10-d-old plants of the barley genotypes Antonia (Mn inefficient) and Vanessa (Mn efficient)

Values for Vmax and the apparent Km were obtained by fitting calculated data of root Mn influx at external Mn2+ concentrations ranging from 10 nm to 655 μm to the Michaelis-Menten equation using nonlinear regression analysis (Fig. 4). Plant characteristics are as in Table I. Values with the same superscript letter were not significantly different between genotypes. The results are presented as average ± 95% confidence limits of four independent regressions (n = 4).

LATSVmaxKmRegression Coefficient
μmol Mn g −1 DW h−1μmR2
Antonia9.1 ± 1.4a109 ± 50a0.980
Vanessa8.5 ± 0.5a79 ± 15a0.990