Comparison of ¹⁵O-Labeled and ¹⁸F-Labeled Water Uptake in a Soybean Plant by PETIS (Positron Emitting Tracer Imaging System)

Abstract

¹⁵O-Labeled and ¹⁸F-labeled water uptake manner in a soybean plant was compared by PETIS (Positron Emitting Tracer Imaging System) . ¹⁵O-Labeled water (half-life: 110 min) and ¹⁸F-labeled water (half-life: 2 min) was produced by a cyclotron by ¹⁴N (d, n) ¹⁵O and ¹⁶O (α, pn) ¹⁸F reactions, respectively. A root of a soybean plant was cut off and each labeled water was supplied from the basal part of the plant. The gamma-rays emitted from the sample was measured by a BGO counter with a detection area of 5 cm × 15 cm. The radioactivity from each stem was accumulated every 15 s till 20 min. It was found that ¹⁸F-labeled water was taken up much faster than ¹⁵O-labeled water, suggesting that in ¹⁸F-labeled water, fluorine was moved in the form of ¹⁸F-ion. When BAS image of ¹⁵O-labeled water in a plant after 5 min and 10 min of water supply was taken, it was found that the labeled water was observed only in the lowest internode, between a root and the first leaves.