MULTIPLE-TRAIT SELECTION IN JACK PINE

Open-pollinated jack pine (Pinus banksiana Lamb.) families were evaluated at four sites in New Brunswick after seven growing seasons for height growth, crown quality, stem straightness, branch angle, and relative branch diameter. Variance and covariance components were estimated to determine heritability of traits and genetic correlations between traits. Results indicated that there is a negative genetic correlation between height growth and all other traits. Selection based on height growth alone would result in degradation of quality traits of secondary economic importance at this age. A restricted selection index approach was examined for family roguing in seedling seed orchards because of the adverse genetic relationships between traits. Such an approach may be used to hold secondary quality traits constant, although some loss in maximum potential genetic gain in height at 7 years is incurred.