© 2007 Heron Publishing—Victoria, Canada
Ammonium and nitrate uptake, nitrogen productivity and biomass allocation in interior spruce families with contrasting growth
rates and mineral nutrient preconditioning
Brad D. Miller (1) and Barbara J. Hawkins (1,2)
1. Centre for Forest Biology, University of Victoria, PO Box 3020, STN CSC, Victoria, BC V8N 1J3, Canada / 2. Corresponding author (bhawkins@uvic.ca) / Received April 4, 2006; accepted September 1, 2006; published online March 1, 2007
Summary
Four full-sib families of interior spruce (Picea glauca (Moench) Voss) × Picea engelmanii Parry ex Engelm.) with contrasting growth rates (two fast-growing and two slow-growing families) were grown aeroponically
with either a 2% relative nitrogen addition rate or free access to nitrogen. Fast-growing families showed greater plasticity
in allocating biomass to shoots at high nitrogen supply and to roots at low nitrogen supply than slow-growing families. Compared
with the slow-growing families, short-term net ammonium uptake rate measured with an ion selective electrode was significantly
greater in fast-growing families at high ammonium supply, but not at low supply. Net nitrate uptake showed the same trend,
but differences among families were not significant. Results indicate that differences in seedling growth rate are partly
a result of physiological differences in net nitrogen uptake efficiency and nitrogen productivity.
Keywords:
ion flux, NH4+, nitrogen uptake, NO3–, steady state, tree improvement.
