Variation in seed set and proportions of outcrossed progeny with clones, crown position, and top pruning in a Douglas-fir seed orchard

Abstract

The effects of clonal variability, crown position of cones, and top pruning on the proportions of viable outcrossed progeny [Formula: see text] and filled seeds (PF) were investigated in a 20-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seed orchard. Estimates of [Formula: see text] were derived by means of a maximum likelihood procedure from data from 10 allozyme loci. Values for [Formula: see text] and PF were significantly heterogeneous (P < 0.05) among six selected clones for all pruning treatment x clone combinations. On the average, estimated values for [Formula: see text] and [Formula: see text] were greater in seeds collected from the upper crown [Formula: see text] than from the lower crown [Formula: see text]. Combined over crown positions, pruning appeared to have little effect on [Formula: see text], although the proportion of filled seeds was slightly lower in pruned ramets [Formula: see text] than in unpruned ramets [Formula: see text]. The overall frequency of viable selfs [Formula: see text] in the progeny of the six clones was 0.08.