Genetic improvement of wood density and radial growth in Larix kaempferi: results from a diallel mating test

Abstract

Wood density is an important component of wood quality, and it is therefore important to assess whether it can be subject to genetic improvement. We assessed the potential for genetic improvement of wood density in Larix kaempferi by recording components of annual growth rings. A full diallel mating test based on six plus L. kaempferi trees was used. Trees were 29 years old. Wood density was recorded by soft X-ray densitometry, and genetic parameters and genetic gains were computed. Wood density of mature wood was highly heritable, and the largest heritability (0.78) was reached at age 25. Specific combining ability and reciprocal effects displayed very low variance. The age–age correlation of overall wood density was very high (>0.94). The genetic correlation between overall wood density and basal cross-sectional area was positive after age 10. Early selection at age 6 would account for 69 % of the genetic gain from direct selection at age 28 in terms of wood density. Genetic improvement of wood density could be achieved by mass selection and a simultaneous selection for radial increment in L. kaempferi; early selection for wood density can be achieved in this species.