title: Modelling postsilking nitrogen fluxes in maize (Zea mays) using 15N-labelling field experiments.
abstract: In maize (Zea mays), nitrogen (N) remobilization and postflowering N uptake are two processes that provide amino acids for grain protein synthesis. To study the way in which N is allocated to the grain and to the stover, two different 15N-labelling techniques were developed. 15NO(3-) was provided to the soil either at the beginning of stem elongation or after silking. The distribution of 15N in the stover and in the grain was monitored by calculating relative 15N-specific allocation (RSA). A nearly linear relationship between the RSA of the kernels and the RSA of the stover was found as a result of two simultaneous N fluxes: N remobilization from the stover to the grain, and N allocation to the stover and to the grain originating from N uptake. By modelling the 15N fluxes, it was possible to demonstrate that, as a consequence of protein turnover, a large proportion of the amino acids synthesized from the N taken up after silking were integrated into the proteins of the stover, and these proteins were further hydrolysed to provide N to the grain.
authors.affiliation: Station de Génétique Végétale, INRA-UPS-INAPG-CNRS, Ferme du Moulon, 91190 Gif/Yvette, France. gallais@moulon.inra.fr
authors.forename: André
authors.initials: A
authors.lastname: Gallais
authors.forename: Marie
authors.initials: M
authors.lastname: Coque
authors.forename: Isabelle
authors.initials: I
authors.lastname: Quilléré
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Prioul
authors.forename: Bertrand
authors.initials: B
authors.lastname: Hirel
mesh_terms: D007553:Isotope Labeling / Q000379:methods; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes; D010940:Plant Proteins / Q000378:metabolism; D012639:Seeds / Q000254:growth & development / Q000378:metabolism; D003313:Zea mays / Q000254:growth & development / Q000378:metabolism*
chemical_list: D009587:Nitrogen Isotopes; D010940:Plant Proteins; D009584:Nitrogen