Estimating Genetic Parameters of Height Growth in Seven-Year Old Coastal Douglas-Fir from Disconnected Diallels
Abstract:A disconnected diallel mating scheme was carried out on 10 sets of 6 parents each for coastal Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco). After 7 growing seasons in 11 plantations, the total phenotypic variation in height was partitioned into portions of additive genetic effect (GCA) within sets, dominance genetic effect (SCA) within sets, interaction of plantations with additive and dominance genetic effects within sets, residual effect, and random error. The GCA effect of the parent trees within the sets was highly significant, and its variance was the most important genetic source of variation. The GCA by plantation interaction was large, and its variance was approximately 42% of the GCA variance. There were some striking rank changes among the parent trees within sets on different plantations, but such changes in the rank within the sets were confined primarily to those parents in the 18th to 82nd percentlie of the 7-year height distribution. The ranks of the top and the worst general combiners within the sets were generally consistent across the plantations. Effects owing to SCA of parent trees and SCA by plantation interaction were also significant, but their variances were small relative to the GCA variance. The heritability estimate appropriate for mass selection on 7-year height was 0.13. The results are discussed in relation to the gains to be expected from tree improvement for the species. For. Sci. 33(4):946-957.
Document Type: Journal Article
Affiliations: Research Branch, B.C. Ministry of Forests and Lands, 1450 Government Street, Victoria, B.C. Canada V8W 3E7
Publication date: December 1, 1987
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