The feasibility of adding wood quality traits as selection criteria in the Galician Pinus pinaster Aiton breeding program: case study

Pinus pinaster is a very important species for the Galician wood industry. A genetic breeding program was started in the 1980s to select plus trees based on growth and straightness. In this study, we estimated genetic parameters, juvenile-mature correlations and genetic gains in basic density (BD) and the dynamic modulus of elasticity (MOEd) in Galician breeding families, as well as their relation to volume, straightness, and tree slenderness. All traits were measured at a tree age of 12 years in three half-sib progeny trials. Wood quality traits were also measured at 24 years in two other trials. All progeny trials followed a randomized complete block design and the data were analyzed using several mixed-model approaches. The individual heritability of MOEd remained stable at both ages (similar to 0.39) but decreased with age for BD (from 0.44 at age 12 to 0.24 at age 24). The high juvenile-mature correlations (0.51 for BD, 0.57 for MOEd) observed support the viability of early selection for both traits at 12 years. Both wood quality traits correlated positively with each other and weakly with volume, straightness and tree slenderness. Selecting a minimum number of the best families, based on volume or any wood quality trait, would generate genetic gains for the selecting trait and prevent genetic losses of non-selecting traits. We also identified specific families showing positive genetic gains for all traits. The research indicates that either or both of these wood quality traits could be included as new selection criteria in the Galician breeding program.