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Inbreeding depression in selfs of redwood

Informally Refereed
Authors: W. J. Libby, B. G. McCutchan, C. I. Millar
Year: 1981
Type: Miscellaneous Publication
Station: Pacific Southwest Research Station
Source: Silvae Genetica 30(1): 15-29


Given the polyploid chromosome constitution of Sequoia sempervirens, there was reason to question whether it would exhibit inbreeding depression. Preliminary results from studies of self and related outcross families are reported as a guide to the selection of trees for redwood seed orchards and breeding-orchards. The data indicate that, compared to outcrosses, selfing produced no additional cone abortion, no consistent effect on number of seeds per cone, and variable effects on germination. Consequently,there relative proportions of inbred and outcrossed offspring produced are normally maintained. Under good nursery conditions, survival of selfs and outcrosses was both high and similar. Under stress nursery conditions, survival was lower for both, but selfs had a much lower survival rate than outcrosses. The selfs were consistently 85-80%; the height of the outcrosses in the nursery, and also after one year in the field. Then inbreeding depression appears to become much more severe. After fourteen years in the field, in the single family available, selfs averaged only 42% the height and 29% the diameter of related outcrosses. It thus appears prudent to restrict inbreeding in redwood seed-orchards.


Cone abortion, Diameter, Germination, Height, Nursery practice, Polyploidy, Seed-orchards, Sequoia sempervirens, Stress, Survival


Libby, W. J., McCutchan, B. G., and Millar, C. I. 1981. Inbreeding depression in selfs of redwood. Silvae Genetica 30(1): 15-29