Ref ID: 10201
Ref Type: Journal
Authors: Costa e Silva, J., Borralho, N. M. G., and Potts, B. M.
Pub Date: 2004
Journal Name: Theoretical and Applied Genetics
Volume: 108
Issue: 6
Start Page: 1113
End Page: 1119
ISBN/ISSN:
Keywords: additive genetic variance/analysis/base/breeding/breeding value/breeding value prediction/clonal/clonal replication/cloning/comparison/component/density/diameter/dominance/dominance genetic variance/effect/environment/epistatic genetic variance/Eucalyptus/Eucalyptus globulus/full-sib/gain/genetic/genetic gain/genetic parameters/genotype/globulus/growth/heritability/importance/improvement/interaction/location/merit/objective/P/parameter/parent/pilodyn/Portugal/Portuguese/prediction/progeny/progeny test/seedling/selection/site/sites/strategy/test/trait/value/variance/variation/wood
Abstract: The first estimates of the importance of epistatic effects in Eucalyptus were obtained from analysis of clonally replicated full-sib progeny tests of Eucalyptus globulus ssp. globulus grown in Portugal. Parents comprised diverse selections from the Portuguese landrace. Variance components were estimated for 4-year-old diameter growth and pilodyn penetration, an indirect measure of wood density, both key traits in the pulpwood breeding objective. The experimental components of variance were used to estimate heritabilities and proportions of the phenotypic variance due to dominance and epistasis in within- and across-site analyses. The additive variance was the only significant genetic component affecting either diameter or pilodyn. The only exception was diameter at one site where the component of variation associated with epistasis was marginally significant (P < 0.05), but this may be due to confounding non-genetic effects introduced by cloning. In an across-site analysis, estimates of the additive, dominance and epistatic effects accounted for 10%, 4% and 0.4% of the phenotypic variation in diameter and 17%, 0% and 5% of the phenotypic variation in pilodyn, respectively. Despite the test sites encompassing a diverse range of locations, no important genotype by environment interaction was detected. A comparison of analyses from seedling and clonal progeny tests indicated that clonal replicates increased substantially the accuracy of the offspring breeding value predictions. These results suggest that an improvement strategy combining both recurrent selection for additive genetic merit and clonal testing may be adequate for optimising genetic gains from this genetic base.
Notes: Entered by Brad Potts (17/04/2003)
Reprint: Not in File
Program: SPF Genetic Improvement
Project: A1
Deliverable: A1-1
Confidentiality: Public
Availability: Authors
Report: Annual Report 2003/4
Type: Article
Address: B.M.Potts@utas.edu.au