CHARACTERIZATION OF THE HIGH-AFFINITY K+(RB+)-UPTAKE SYSTEM IN ROOTS OF INTACT TARAXACUM MICROSPECIES - COMPARISON OF 12 MICROSPECIES IN RELATION TO THEIR MINERAL ECOLOGY

Taraxacum microspecies differ with respect to nutritional levels in their habitats. In the context of marked differences in growth response to internal potassium concentration between two ecologically contrasting microspecies, K+‐uptake characteristics, Vm and Km, of the high‐affinity uptake system of 12 microspecies were studied. In this comparative study, CaSO4‐pretreated plants were used. Microspecies differences in Vmax were more abundant than in Km. Significant differences between kinetic parameters of ecologically related groups of microspecies were largely absent; only the (average) Vmax of the group of microspecies derived from heavily fertilized and moist grasslands was higher than those of the remaining three groups of microspecies. Within a taxonomically related group of eight microspecies, variation in Vmax (average) and Km (average) values was almost as high as total variation. The results on kinetic characteristics of the high‐affinity K+‐uptake system are discussed in the context of additional differences in physiology such as the critical internal K+concentration and growth potential between two representative microspecies of different mineral ecology. Copyright © 1990, Wiley Blackwell. All rights reserved