Non‐uniformity of 15n labelling in plant material

Abstract

Data illustrating the diluting effect of distillation of “blank nitrogen”; on the ¹⁵N enrichment of aliquots containing small amounts of ammonium sulphate are presented. Non‐uniformity of ¹⁵N‐labelling of plant material is illustrated by two examples. In one, significant variation in ¹⁵N enrichment is shown for various parts of wheat plants grown in soil to which single addition of labeiled nitrate had been made. In a second example, the enrichment of Rhodesgrass plants grown in sand was found to be lower than that of the labelled nitrogen source, which constituted the only nitrogen added by the experimenter.