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 (~ 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.

Key message The resistance of Pinus pinaster Aiton to pinewood nematode Bursaphelenchus xylophilus (Steiner and Buhrer) varied among populations from the Iberian Peninsula, with survival rates for inoculated seedlings ranging from 5 to 100%. These differences in resistance were paralleled by differences in some constitutive chemical defenses. Populations from the southeastern Iberian Peninsula displayed higher resistance than northern populations. Context The presence of the pinewood nematode (PWN), Bursaphelenchus xylophilus (Steiner and Buhrer), in Portugal threatens Mediterranean pine species such as Pinus pinaster Aiton. Aims We have focused on assessing the resistance of P. pinaster populations to B. xylophilus, looking for any relationship between the PWN resistance and some constitutive chemical defenses and geoclimatic parameters. Methods Two-year-old seedlings from 32 provenances and two seed orchards were evaluated in an experiment of artificial inoculation following a randomized complete block design under greenhouse conditions. We measured growth-related traits, response to B. xylophilus inoculations, and constitutive chemical compounds in needles of the evaluated seedlings and compiled geoclimatic data for each population. Mixed models, nonparametric tests, correlations, and PCA were used to analyze the data. Results Survival, wilting symptoms, morphological traits, and nematode density varied significantly among populations. Lower concentrations of constitutive polyphenols, lipid-soluble substances, and tannins were related to higher PWN resistance. Populations from the southeast of the Iberian Peninsula showed higher survival rates than those from further north. Additionally, we observed that populations to warm, dry climates showed higher resistance to B. xylophilus than populations originating from humid, temperate climates. Conclusion Higher susceptibility to PWN is related to lower growth traits, to lower levels of certain constitutive chemical compounds, and to adaptations to harsher climate.