The effect of potassium nutrition on 137Cs uptake in two upland species

Agrostis capillaris (Agrostis) and Calluna vulgaris (Calluna), two species with differing phenologies and widespread presence in upland areas of Britain where high Chernobyl fallout occurred, were grown in pot culture with varying concentrations of potassium in the rooting medium. Tissue content of potassium increased with increasing supply in both species. Roots, excised from these plants, were placed in a solution of 137-Cs-labelled caesium chloride for 15 min to determine uptake potential. There were clear negative relationships between the rate of uptake of 137Cs by both species and (a) the concentration of potassium supplied and (b) plant tissue potassium concentrations. With Agrostis, there was an approximately ten-fold difference in 137Cs uptake between potassium-deficient and optimum plants; with Calluna, it was approximately eight-fold. These results demonstrate the suppression of 137Cs uptake into plants by potassium supply.