title: Age-age and trait-trait correlations for Eucalyptus grandis Hill ex Maiden and their implications for optimal selection age and design of clonal trials.
abstract: Previous results from seven locations of Eucalyptus grandis clonal trials in Colombia supported the a priori contention of sub-dividing them into three different environmental zones for testing and deployment. Within these zones, the determination of age-age genetic correlations for both height and mean annual increment (MAI) showed that strong age-age correlations are present for a rotation age of 6 years starting at 3 years age and, thereafter, suggesting this age as appropriate for selection. This biological selection age coincides with an "economical" age for selection based on discounted selection efficiency in perpetuity, considering a range of interest rates between 10% and 20%. High genetic correlations between wood density at 3 years and 6 years as well as the lack of genetic correlation between this trait and growth traits, also favors selection at age 3 and facilitates breeding strategies that consider the utilization of both traits for improvement. A simulation of optimal clonal test designs indicated that by using six locations and six blocks per location in a single-tree plot design, between 80% and 90% of the maximum selection efficiency could be obtained. This type of design allows testing of a large number of genotypes across a reasonable number of locations in a cost-effective manner.
authors.forename: L F
authors.initials: LF
authors.lastname: Osorio
authors.forename: T L
authors.initials: TL
authors.lastname: White
authors.forename: D A
authors.initials: DA
authors.lastname: Huber
mesh_terms: D002874:Chromosome Mapping; D003433:Crosses, Genetic; D005052:Eucalyptus / Q000235:genetics*; D005838:Genotype; D015233:Models, Statistical; D010641:Phenotype; D012641:Selection, Genetic; D013045:Species Specificity; D013997:Time Factors