A genetic test of 104 full-sib families of low elevation, coastal Douglas-fir (Pseudotsuga menziesii (MIRB.) FRANCO) was evaluated 3 years after germination. The full-sib families were produced by a disconnected diallel mating scheme, consisting of 7 sets of B-parent Partial diallels, grown under 2 spacing treatments in a nursery. The objectives of the study were to determine the extent of genetic control of growth traits, biomass distribution and allocation strategies, and vegetative phenology. Spacing had a significant Effect on 6 of the 11 traits studied. Significant general combining ability variance was found for all traits except 1-year height. Individual tree narrow-sense heritability varied from 0.06 to 0.69 for root-dry-weight to vegetative phenology, respectively. Spacing x family interaction variance was significant for only 2 traits. Two harvest indices, based on total and above ground dry weights, were used to assess dry matter allocation strategy and to Explore potential usefulness in tree breeding. Both indicts had similar heritability estimate-a and their genetic correlation was high (0.91), indicating that use of an index based on above ground dry weight is a good surrogate for that based on total dry weight. Genetic correlations among growth and biomass traits were generally high, while those correlations with harvest indices were variable.
