Genetic correlations among wood, growth capacity and stem traits in Pinus sylvestris

Wood density and tracheid length are two traits that significantly affect w ood products. Genetic correlations were estimated to evaluate the effect on these traits from a selection for traits included in the Swedish Pinus syl vestris L, breeding programme. Measurements from a non-contiguous single-tr ee plot progeny trial with controlled matings between 30 parent trees was u sed. Heritabilities were high for the wood traits, intermediate for the gro wth capacity traits and low for the stem traits, with the exception of bran ch angle. Wood density showed no or non-significant negative genetic correl ations with the growth capacity traits and a positive correlation with rela tive branch diameter. Tracheid length showed positive genetic correlations with height and a positive correlation with relative branch diameter. A sel ection that increased height growth at the age of 13 yrs by 10% was expecte d to decrease mean wood density at 33 yrs by 1%. The expected correlated re sponse to tracheid length from the same selection was a 3% increase in the juvenile and mature wood.