Abstract
Uptake of the cytokinin benzyladenine by tuber slices of Jerusalem artichoke (H. tuberosus L.) increased with the concentration of benzyladenine in the medium, in the range of 10-8-10-4 M. The kinetics of uptake could be precisely represented by 4 phases of a single, multiphasic isotherm. Km and Vmax increased in a regular manner upon transition to higher phases. The fit to multiphasic kinetics was significantly better than the fit to cooperative kinetics or to the sum of 4 independent Michaelis-Menten terms.