Self-Fertilization Rates in White Spruce: Effect of Pollen and Seed Production

The effect of variable pollen and seed production on the mating system of white spruce was examined over 2 years in a clonal seed orchard. Clones produced 0 to 53,345 male strobili each and 0 to 37,449 female strobili each and selfed at rates ranging from 0 to 22%. The self-fertilization rates of individual clones were correlated with clonal male strobilus numbers. The selfing rate for the orchard population was estimated to be significantly greater when clonal variation in seed production was accounted for than when equal seed production by clones was assumed. The variation in male and female strobilus production may contribute significantly to inbreeding in white spruce.