The Uptake of Inorganic Ions by Plant Leaves

A technique for estimating the gross uptake of ions by plantleaves is described. Uptake of strontium-89 and caesium-137from droplets applied to plant leaves was greatly affected bythe humidity of the air, the effect being markedly dependenton the initial concentration of the solution. Uptake was greaterin light than in darkness; the effect of temperature was relativelysmall. The percentage uptake of the nuclides was reduced only to arelatively small extent as the concentration of carrier ionwas increased. This was in marked contrast to the situationwhen leaves were fully immersed in solution. ¹³⁷Cs was takenup to a greater extent than iodine, phosphate, or sulphate.The role of exchange and of fixed negative charges in uptakeis discussed.