| Summary: | Biological aspects of orchard-produced Sitka spruce (Picea sitchensis (Bong.) Carr.)
seeds were studied for one seed orchard located on the Saanich Peninsula of Vancouver Island,
B.C. These aspects include: the determination the level of genetic diversity in the orchard
population and its comparison to the species' range estimates, the estimation of the degree of
inbreeding in the orchard, seed and cone crop parental balance over t w o crop years, the
genetic control of germination parameters and seed size , the impact of simulated long-term
storage on the genetic constitution of bulk seed crops , and the relationships between seed size
and genetic origin on their seedling attributes. It was found that: (1 ) Most of the polymorphic
allozyme markers investigated segregated according to the expected Mendelian ratio, and no
linkage between any pair of these loci was observed; (2) The level of genetic diversity present
in the seed orchard population indicated that phenotypic selection of parent trees did not
reduce the level of diversity; (3) Significant rates of outcrossing were detected in the seed
orchard population ( t „ = 0 . 8 7 5 ) . Most of this inbreeding occurred in lower branches; (4)
Parental imbalance was found for the two crops investigated, however, improvement over time
was observed, indicating an age effect; (5) Germination parameters (GC, P V and GV) and seed
size were under genetic control with estimates of broad-sense heritabilities of 0 . 74 - 0.78 and
0.36 , respectively; (6) Artificial aging of seed (i.e., accelerated aging) indicated that reduction
in rates of germination were clone-specific; and (7) Seed size showed no effect on seedling
attributes, but a significant effect on germination speed was observed. === Forestry, Faculty of === Graduate
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