Canadian Forest Service Publications
Selection for an optimum tree growth curve. 1993. Magnussen, S.; Kremer, A. Silvae Genetica 42(6): 322-335.
Available from: Pacific Forestry Centre
Catalog ID: 4411
Height growth trajectories of 100 half-sib families of Pinus pinaster Arr. were subject to selection that aimed at a constant improvement (here 20%) for all ages or a gradual improvement of p · log(age) · 100% (here p = 0.05). Height growth was under strong additive genetic control and prospects of genetic gain were promising. A 2nd degree polynomial on a log-log scale was successfully used to describe the height-age relationship in all trees. Classical Smith-Hazel selection indices, growth curve parameter indices, and continuous selection indices were also computed for the 2 improvement objectives. The continuous selection index was a second degree polynomial on a log transformed time scale derived from stochastic integration of covariance kernels. Results suggest that selection on the growth curve continuum is more efficient for both mass selection and family selection because it utilized more information than selection at discrete ages. The latter had to be restricted to 3 distinct ages in order to avoid singularity of covariance matrices. Selection on growth curve parameters was intermediate in efficiency.