Labelling plants in the Chernobyl way: A new 137Cs and 14C foliar application approach to investigate rhizodeposition and biopore reuse

Background and aims: Biopores as microbial hotspots provide additional nutrients to crops – but only if their roots grow within the biopores. Such reuse has never been quantified as pre-crop-specific biopores are hardly differentiated from the multitude of pre-existing biopores. Quantification requires e.g. radionuclide labelling of pre-crops (137Cs, to label their biopores) and main crops (14C, to detect new roots). Preliminary testing was performed on simulated biopore reuse: both nuclides given to the same plant were excreted into the same rhizosphere. Methods: Cichorium intybus (cv. Puna) and Medicago sativa (cv. Planet) were each sequentially labelled via the leaves with 137Cs and 14CO2. β-signals were visualised by imaging of horizontal soil cuts - with and without shielding off the weaker 14C. Results: Both species allocated 7.1–9.4% of the 137Cs and 21–63% of the 14C below ground. The first image gave both activities; while the second gave only 137Cs. Subtracting the second from the first image gave the 14C distribution, resulting in successful separation of the signals. Thus, separate spatial representations of the roots were obtained. Main root locations by 137Cs and 14C showed a very high spatial overlap coefficient (\textgreater 0.95). Conclusions: Biopore reuse quantification likely becomes feasible with this sequential labelling and shielding approach.     «

Background and aims: Biopores as microbial hotspots provide additional nutrients to crops – but only if their roots grow within the biopores. Such reuse has never been quantified as pre-crop-specific biopores are hardly differentiated from the multitude of pre-existing biopores. Quantification requires e.g. radionuclide labelling of pre-crops (137Cs, to label their biopores) and main crops (14C, to detect new roots). Preliminary testing was performed on simulated biopore reuse: both nuclides giv...     »