title: Insights into nitrogen allocation and recycling from nitrogen elemental analysis and 15N isotope labelling in 14 genotypes of willow.
abstract: Minimizing nitrogen (N) fertilization inputs during cultivation is essential for sustainable production of bioenergy and biofuels. The biomass crop willow (Salix spp.) is considered to have low N fertilizer requirements due to efficient recycling of nutrients during the perennial cycle. To investigate how successfully different willow genotypes assimilate and allocate N during growth, and remobilize and consequently recycle N before the onset of winter dormancy, N allocation and N remobilization (to and between different organs) were examined in 14 genotypes of a genetic family using elemental analysis and (15)N as a label. Cuttings were established in pots in April and sampled in June, August and at onset of senescence in October. Biomass yield of the trees correlated well with yields recorded in the field. Genotype-specific variation was observed for all traits measured and general trends spanning these sampling points were identified when trees were grouped by biomass yield. Nitrogen reserves in the cutting fuelled the entirety of the canopy establishment, yet earlier cessation of this dependency was linked to higher biomass yields. The stem was found to be the major N reserve by autumn, which constitutes a major source of N loss at harvest, typically every 2-3 years. These data contribute to understanding N remobilization in short rotation coppice willow and to the identification of traits that could potentially be selected for in breeding programmes to further improve the sustainability of biomass production.
authors.affiliation: Division of Biology, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Nicholas J B
authors.initials: NJ
authors.lastname: Brereton
authors.affiliation: Institut de recherche en biologie vegetale, University of Montreal, 4101 Sherbrooke East, Montreal QC H1X 2B2, Canada.
authors.forename: Frederic E
authors.initials: FE
authors.lastname: Pitre
authors.affiliation: Department of AgroEcology Rothamsted Research, Harpenden, Herts AL5 2JQ, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Shield
authors.affiliation: Department of AgroEcology Rothamsted Research, Harpenden, Herts AL5 2JQ, UK.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Hanley
authors.affiliation: Division of Biology, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ray
authors.affiliation: Faculty of Engineering & Physical Sciences, Centre for Environmental Strategy, University of Surrey, Guildford, Surrey GU2 7XH, UK.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Murphy
authors.affiliation: Department of AgroEcology Rothamsted Research, Harpenden, Herts AL5 2JQ, UK angela.karp@rothamsted.ac.uk.
authors.forename: Angela
authors.initials: A
authors.lastname: Karp
mesh_terms: D056804:Biofuels; D001692:Biological Transport; D018533:Biomass; D001947:Breeding; D005838:Genotype; D007553:Isotope Labeling; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes / Q000032:analysis; D009928:Organ Specificity; D010641:Phenotype; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D018547:Plant Stems / Q000254:growth & development / Q000378:metabolism; D032108:Salix / Q000254:growth & development / Q000378:metabolism*; D014197:Trees
chemical_list: D056804:Biofuels; D009587:Nitrogen Isotopes; D009584:Nitrogen
keywords: biofuel; biomass; nitrogen-use-efficiency; short rotation coppice willow