Genetic variation of wood density components in a radiata pine progeny test located in the south of Chile

This article describes changes in the genetic variation of wood density components with cambial age and their relationship with the within-ring area components. Wood samples from 31 half-sib families of radiata pine were submitted to X-ray densitometry procedures. Traits studied were earlywood (ED) and latewood (LD) density, earlywood (EA) and latewood (LA) area, and latewood proportion (LP). Between rings 2 to 5 (juvenile wood) and 11 to 14 (mature wood), heritability estimates suggest that breeding for increased ED is feasible. Upward selection for ED would also be associated with a phenotypic reduction in EA in juvenile and mature wood. Between rings 6 to 10, the heritability estimates for ED indicate low genetic variation in the transition region. Attempts to increase ED by breeding might not have a significant impact on LD, though this trait showed a moderate genetic control in this region. Any change in ED and LD would have unclear effects on EA and LA, respectively, because of the changing pattern of genetic covariances.