Age-age and trait-trait correlations for Eucalyptus grandis Hill ex Maiden and their implications for optimal selection age and design of clonal trials

• Published in: Theoretical and applied genetics Vol. 106; no. 4; pp. 735 - 743
• Main Authors: OSORIO, L. F, WHITE, T. L, HUBER, D. A
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-02-2003; Berlin Springer Nature B.V
• Subjects: Age; Biological and medical sciences; Chromosome Mapping; Classical genetics, quantitative genetics, hybrids; Cloning; Crosses, Genetic; Discount rates; Efficiency; Eucalyptus - genetics; Fundamental and applied biological sciences. Psychology; Genetics of eukaryotes. Biological and molecular evolution; Genotype; Models, Statistical; Phenotype; Pteridophyta, spermatophyta; Selection, Genetic; Species Specificity; Time Factors; Vegetals; Colombia; Genetic selection; Correlation; Clonal locations; Design; Eucalyptus grandis; Dicotyledones; Angiospermae; Selection age; Myrtaceae; Genetics; Clonal selection; Spermatophyta; Hardwood forest tree; Age; Genetic correlations
• ISSN: 0040-5752; 1432-2242
• DOI: 10.1007/s00122-002-1124-9

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.