Potassium uptake by higher plants: From field application to membrane transport

Potassium (K+) is a crucial nutrient element for higher plants and plays vital roles in several cellular processes includingturgor regulation, stomatal movement, protein synthesis and charge balance. The requirement of K+for plant growth changes with the developmental stages and its uptake pattern varies among crop plants. Most annual crop plants take up a large proportion of their K+requirement in the initial vegetative growth stage. A deficiency of K+during this period may make the plant susceptible to various stresses. Therefore, the timely application of K+to the plant rhizosphere is an important factor for achieving better plant growth and yield. Plants take up K+by active and passive transport. Electrophysiological and molecular studies done during the last two decades have characterized the active K+ uptake mechanisms (high and low affinity K+ uptake systems) and have identified the genes involved in these mechanisms. The knowledge of K+uptake during the plant life cycle and of the activation of the K+uptake system by the presence of a certain concentration of K+in the soil solution would certainly help in planning the rate and time of K+application. Therefore, the work done on the pattern of K+uptake during plant growth and the mechanism involved in its uptake is reviewed here.