title: Translocation and re-translocation of selenium taken up from nutrient solution during vegetative growth in spring wheat.
abstract: BACKGROUND
  Selenium (Se) is an essential micronutrient for humans, but the Se level in food plants in northern Europe is generally inadequate to meet human nutritional requirements. Commonly, food plant Se fortification is achieved by selenate fertilisation, but the effect of nitrogen (N) and sulphur (S) supply on the translocation and re-translocation of Se is unknown. Therefore the effect of N and S supply on ⁷⁵selenate/⁷⁵Se translocation and re-translocation during vegetative growth in spring wheat (Triticum aestivum) was studied.
  
  
  RESULTS
  The ⁷⁵Se activity in wheat varied from 148 to 549, from 277 to 1815 and from 171 to 1343 Bq ⁷⁵Se in plants exposed at Zadoks growth stages Z1.4, Z1.5 and Z1.6 respectively. Approximately 85% of the plant ⁷⁵Se was translocated into young leaves. High N supply enhanced the re-translocation of ⁷⁵Se from the stem to maturing leaves, while S inhibited this process. The relative proportion of ⁷⁵Se in L4, L5 and L6 increased with increasing N supply at low sulfate concentrations.
  
  
  CONCLUSIONS
  Selenium in the stem is more re-transportable than Se in the leaves, and the re-translocation is dependent on sulfate supply. When the sulfate supply is sufficient for plant development, less ⁷⁵Se is re-translocated from older to growing leaves.
authors.affiliation: Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, PO Box 5003, N-1432 Ås, Norway. espen.govasmark@umb.no
authors.forename: Espen
authors.initials: E
authors.lastname: Govasmark
authors.forename: Brit
authors.initials: B
authors.lastname: Salbu
mesh_terms: D001692:Biological Transport; D005308:Fertilizers; D009584:Nitrogen / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism; D018547:Plant Stems / Q000378:metabolism; D064586:Selenic Acid; D012643:Selenium / Q000493:pharmacokinetics*; D018036:Selenium Compounds / Q000493:pharmacokinetics*; D013455:Sulfur / Q000378:metabolism*; D014908:Triticum / Q000254:growth & development / Q000378:metabolism*
chemical_list: D005308:Fertilizers; D018036:Selenium Compounds; D013455:Sulfur; D012643:Selenium; D064586:Selenic Acid; D009584:Nitrogen