Factors Affecting Potassium Uptake and Loss by Beech Mycorrhiza

Abstract

SUMMARY Maximum potassium uptake is achieved by beech mycorrhizas from concentrations of chloride of about 0.2 mM. Addition of NaCl up to 0.5 mM does not significantly reduce K+ uptake from 0.1 mM chloride solutions, although the KCl significantly reduces Na+ uptake. Potassium is rapidly lost from mycorrhizal tissues at temperatures above 20° C, but only after some delay from tissues at lower temperatures. Addition of calcium ions (up to 1.0 mM CaCl2) does not significantly affect potassium uptake or loss. CaCl2 added to RbCl solutions slightly reduces Rb+ uptake. Losses of K+ from mycorrhizal tissues at temperatures above 20°C may be prevented by the application of glucose or fructose. Neither the process of carbohydrate uptake nor the increased internal concentration of carbohydrate itself is responsible for the reduction in potassium loss. It seems probably that factors bringing about the retention of potassium are generated in carbohydrate metabolism. The potassium loss engendered by high osmotic pressure of the external solution seems to be a separate phenomenon from that which occurs at high temperatures.

Mycorrhizas of Autotrophic Higher Plants

“…Of the major nutrients, changes in potassium concentrations are most interesting and may be related to nitrogen nutrition (see above). Increased potassium concentration in ectomycorrhizal plants has been reported consistently (see Harley, 1969), and may be the result of rapid absorption of potassium, which has been shown to occur in excised beech mycorrhizas (see Edmonds, Wilson & Harley, 1976). Storage of potassium carboxylate in cell vacuoles would fit with the observation that potassium is ' bound' by substances (i.e.…”

“…Increased potassium concentration in ectomycorrhizal plants has been reported consistently (see Harley, 1969), and may be the result of rapid absorption of potassium, which has been shown to occur in excised beech mycorrhizas (see Edmonds, Wilson & Harley, 1976). Increased potassium concentration in ectomycorrhizal plants has been reported consistently (see Harley, 1969), and may be the result of rapid absorption of potassium, which has been shown to occur in excised beech mycorrhizas (see Edmonds, Wilson & Harley, 1976).…”

Effects of aluminium and pH on growth and potassium uptake by three ectomycorrhizal fungi in liquid culture

“…The temperature was controlled at 20°C and air was bubbled through the incubation medium. According to Harley and Wilson (1959) and Edmonds et al (1976) these factors prevent K + loss in beech mycorrhizas. At regular time intervals during the incubation, samples were taken from the medium and the K ~ concentrations were determined by flame spectrophotometry.…”

Salt Uptake and Respiration of Excised Beech Mycorrhizas

“…Table 6, however, shows that the rate of phosphate absorption over a period of 1-75 h is not closely related to the cation with which it is associated. Potassium is absorbed at about twice the rate of sodium from equivalent concentrations of their chlorides (Edmonds, Wilson and Harley, 1976), yet the uptake of phosphate from their phosphates is not very different. We may therefore conclude that the effect of ammonium upon phosphate incorporation over short times is related to the utilization of ATP in the process of its uptake and in the synthesis of glutamine from it (see Harley, 1964;Carrodus, 1966).…”