Approaches for nondestructive spatial distribution measurements in whole plants using radionuclides

The possibilities of in vivo 1D and 3D imaging of gamma-emitting radionucli des are explored on the whole plant level, using Tc-99m and Se-75 in a case study. Both imaging approaches showed a linearity between the counting sig nal of the system and the radioactivity in the individual leaves. A radioac tivity level down to 10 kBq per leaf was determined adequately, correspondi ng to 19 fmol Tc or 58 nmol Se. However, the complex plant geometry of the tomato plants (Lycopersicon esculentum Mill, cv. Tiny Tim) required the 3D approach for studying the distribution of root-added [Tc-99m]TcO4- and [Se- 75]SeO42- in dual tracer experiment. Both tracers showed a similar distribu tion pattern, probably dependent on the transpiration stream. In contrast, the redistribution of the tracers was shown to be quite different; almost a ll Tc remained in one preloaded mature leaf, while 96.4% of the Se was redi stributed within 21 days. The potential of the presented imaging approaches is discussed in the field of plant research.