© 2007 Heron Publishing—Victoria, Canada
Family variation in nutritional and growth traits in Douglas-fir seedlings
B. J. Hawkins
Centre for Forest Biology, University of Victoria, PO Box 3020 STN CSC, Victoria, BC V8W 3N5, Canada (bhawkins@uvic.ca) / Received May 31, 2006; accepted August 2, 2006; published online March 1, 2007
Summary
Nitrogen (N) uptake and utilization in seedlings of six full-sib families of coastal Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) known to differ in growth rate were assessed at the whole plant and root levels. Seedlings were grown in
soil or aeroponically with high and low nutrient availability. Consistent family differences in growth rate and N utilization
index were observed in both soil and aeroponic culture, and high-ranking families by these measures also had greater net N
uptake in soil culture. Two of the three families found to be fast-growing in long-term field trials exhibited faster growth,
higher N utilization indices and greater net N uptake at the seedling stage. Mean family net influx of ammonium (NH4+) and efflux of nitrate (NO3–) in the high- and low-nutrient treatments were significantly correlated with measures of mean family biomass. The high-nutrient
availability treatment increased mean net fluxes of NH4+ and NO3– in roots. These results indicate that efficiency of nutrient uptake and utilization contribute to higher growth rates of
trees. Nutrient-related traits should be considered in tree breeding programs, as the indications are that assessments may
be made at an early stage.
Keywords:
aeroponic, ammonium flux, microelectrodes, nitrate flux, nitrogen uptake, nitrogen use, nitrogen utilization index.
