Present status of applications of short-lived radioisotopes in agriculture and biology

Short-lived radioisotopes (RI) have potential advantages in agricultural and biological fields, including minimal exposure doses, simple disposal of radioactive wastes, and double-labeling of long- and short-lived RI. The applications of short-lived RI in agriculture and biology were surveyed by reviewing 50 scientific journals. RI examined were C-11, N-13, F-18, Na-24, K-42, K-43, Mg-28, Cu-64, Mo-93m, and Mo-99. C-11 has been used mainly in plant studies on photosynthesis and movement of assimilatory products, and in an animal study on in vivo localization of C-11 labeled amino acids by external scintigraphy. Studies with N-13 have related to denitrification, nitrogen-fixation, nitrogen absorption and metabolism in plants, and nitrogen absorption in animals. The application of Na-24 and Mg-28 has been uncommon. (Namekawa, K.)