Kinetics of zinc absorption by excised roots of two sugarcane clones

Sugarcane clones differ in regard to susceptibility to zinc (Zn²+) deficiency in the field. Excised roots of clone H57-5174 actively absorbed Zn²+ at a rate twice that of H53-263 roots. The maximum rates of Zn²+ uptake (Vmax) and the Km values also. differed markedly between these two clones. H53-263 roots have a 6-fold greater affinity for Zn²+ than do those of H57-5174. H57-5174 readily develops Zn²+ deficiency symptoms in the field but H53-263 rarely does so. A partial explanation for these varying responses appears to lie in these data.