Production of positron emitters of metallic elements to study plant uptake and distribution

Abstract

The metallic positron emitters 52Mn, 52Fe and 62Zn, the elements of which are essential nutrients for plants as well as for animals, have been produced for a new tracer method in plant physiology. The tracer method utilizes the detection of annihilation γ-rays, like PET in nuclear medicine, to obtain two-dimensional images on a plant as well as to obtain radioactivity counts at specified points in a plant; this method allows us to observe the tracer movement in a living plant without touching the test plant. The previously reported methods of radiochemical separation of these metallic positron emitters from targets were partly modified from the view of their use in plant physiology. Radionuclidic impurities remaining in the final solutions were examined by γ-ray spectrometry, and their influences on the above-mentioned measurements are discussed. From the experiments on a barley plant, the speeds of 52Mn2+ ion and 52Fe3+-mugineic-acid complex have been obtained for the first time to be 0.2 cm/min and 1.0 cm/min, respectively.