Cs-137 uptake in spring wheat (Triticum aestivum L cv Tonic) at varying K supply .1. The effect in solution culture

The effect of varying K supply on Cs-137 uptake in spring wheat (Triticum aestivum L. cv. Tonic) was measured in a solution culture experiment. Wheat was grown in nutrient solution spiked with Cs-137. Treatments were four concentrations of K in solution (resp. 25 mu M, 50 mu M 250 mu M and 1000 mu M, added as KNO3) with twofold replication. Cs-137 Activity Concentrations (AC, dry weight based values) in 18-day old plants decreased 123-fold in the shoot and 300-fold in the root between 25 mu M K and 1000 mu M K. Uptake of Cs-137 was most sensitively affected by the K supply between 50 mu M and 250 mu M K. A comparison of the K/Cs-37 ratio in plant and in solution shows that K is from 3.9- to 25-times more selectively taken up than Cs-137. It is discussed that the sensitivity of the Cs-137 uptake rate to the K concentration may explain the beneficial effect of increased K supply in reducing Cs-137 uptake from contaminated soils.