A STUDY OF THE SULPHUR METABOLISM OF WHEAT, BARLEY AND CORN USING RADIOACTIVE SULPHUR

Abstract

Radioactive sulphur (S35) with its weak beta radiation of 0.120 M.E.V. and its long half-life of 87 to 88 days (6, 8) has desirable characteristics as a biological tracer, particularly since its activity can be readily measured after recovery as barium sulphate (6). Further, as will be shown in the following paper (5), excellent autographs of thin sections of plant material can be made on photographic film. Seaborg (9) and Hamilton (3, 4) have reviewed the literature up to 1941 on the use of radioactive elements as tracers in chemical and biological work. Radiosulphur in synthetic cystine, methionine, and thiamin as well as inorganic compounds, has been used in nutritional studies of animals (1,10), but so far as is known, nutritional studies of plants using radiosulphur have not been reported. This paper describes experiments carried out in 1942 with radiosulphur furnished as barium sulphate*2 by Dr. J. G. Hamilton of the Radiation Laboratory, University of California. The sulphur* was added to vegetation growing in the large sand cultures (13) both as a soluble sulphate* in the nutrient solution and as sulphur* dioxide in the air. No radiosulphur was available during the 1943 season.