title: Foliar uptake of radiocaesium from irrigation water by paddy rice (Oryza sativa): an overlooked pathway in contaminated environments.
abstract: Flooded (paddy) rice (Oryza sativa) can take up ions from the irrigation water by foliar uptake via the exposed stem base. We hypothesised that the stem base uptake of radiocaesium (RCs) is a pathway for rice grown in RCs-contaminated environments. We developed a bi-compartmental device which discriminates the stem base from root RCs uptake from solutions, thereby using RCs isotopes (137Cs and134Cs) with < 2% solution leak between the compartments. Radiocaesium uptake was linear over time (0-24 h). Radiocaesium uptake to the entire plant, expressed per dry weight of the exposed parts, was sixfold higher for the roots than for the exposed stem base. At equal RCs concentrations in both compartments, the exposed stem base and root uptake contributed almost equally to the total shoot RCs concentrations. Reducing potassium supply to the roots not only increased the root RCs uptake but also increased RCs uptake by the stem base. This study was the first to experimentally demonstrate active and internally regulated RCs uptake by the stem base of rice. Scenario calculations for the Fukushima-affected area predict that RCs in irrigation water could be an important source of RCs in rice as indirectly suggested from field data.
authors.affiliation: Biosphere Impact Studies, SCK CEN, Belgian Nuclear Research Centre, Boeretang 200, B-2400, Mol, Belgium.|Division of Soil and Water Management, KU Leuven, Kasteelpark Arenberg 20, B-3001, Leuven, Belgium.
authors.forename: Shinichiro
authors.identifier: http://orcid.org/0000-0001-9606-7303
authors.initials: S
authors.lastname: Uematsu
authors.affiliation: Biosphere Impact Studies, SCK CEN, Belgian Nuclear Research Centre, Boeretang 200, B-2400, Mol, Belgium.
authors.forename: Hildegarde
authors.initials: H
authors.lastname: Vandenhove
authors.affiliation: Biosphere Impact Studies, SCK CEN, Belgian Nuclear Research Centre, Boeretang 200, B-2400, Mol, Belgium.
authors.forename: Lieve
authors.initials: L
authors.lastname: Sweeck
authors.affiliation: Biosphere Impact Studies, SCK CEN, Belgian Nuclear Research Centre, Boeretang 200, B-2400, Mol, Belgium.
authors.forename: May Van
authors.initials: MV
authors.lastname: Hees
authors.affiliation: Biosphere Impact Studies, SCK CEN, Belgian Nuclear Research Centre, Boeretang 200, B-2400, Mol, Belgium.
authors.forename: Jean
authors.initials: J
authors.lastname: Wannijn
authors.affiliation: Division of Soil and Water Management, KU Leuven, Kasteelpark Arenberg 20, B-3001, Leuven, Belgium.
authors.forename: Erik
authors.initials: E
authors.lastname: Smolders
mesh_terms: D057914:Agricultural Irrigation; D002588:Cesium Radioisotopes / Q000378:metabolism*; D007700:Kinetics; D012275:Oryza / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism; D018547:Plant Stems / Q000187:drug effects / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D012996:Solutions; D014878:Water Pollution, Radioactive / Q000032:analysis*
chemical_list: D002588:Cesium Radioisotopes; D012996:Solutions; D011188:Potassium
keywords: Oryza sativa (rice); foliar uptake; potassium; radiocaesium; root uptake; stem base; translocation