Local and systemic effects of phosphorus and nitrogen on nodulation and nodule function in Alnus incana.
Phosphorus (P) and nitrogen (N) effects on nodulation, nitrogenase activity and plant growth were studied in the root-hair-infected actinorhizal plant Alnus incana (L.) Moench. A split-root experiment, as well as a short-term experiment with entire root systems and a broader range of P concentrations, showed that P effects were specific on nodulation and not a general stimulation via a plant growth effect. These results indicate that nodule initiation and nodule growth have a high P demand. The split-root assay, comprising seven combinations of two N and two P levels, showed that P could counteract systemic N inhibition of nodulation, but did not counteract N inhibition of nitrogenase activity.
Department of Agricultural Research for Northern Sweden, Crop Science Section, Swedish University of Agricultural Sciences, Box 4097, S-904 03 Umeå, Sweden. Francesco.Gentili@plantphys.umu.se
Francesco
F
Gentili
Kerstin
K
Huss-Danell
D029661:Alnus / Q000187:drug effects / Q000254:growth & development*; D007700:Kinetics; D009584:Nitrogen / Q000494:pharmacology*; D010758:Phosphorus / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development*
D010758:Phosphorus; D009584:Nitrogen