Partitioning of genetic variance and selection efficiency for alternative vegetative deployment strategies for white spruce in Eastern Canada

Abstract

Genetic variances and selection efficiencies for growth traits of white spruce (Picea glauca (Moench) Voss) were estimated from clonally replicated full-sib progeny tests established both in nursery and field environments in New Brunswick, Canada. The available data included heights at 4, 5, and 6 years in the nursery test; height at 9 years, height, DBH, and volume at 14 years in the field test. Estimated variance components were interpreted according to an additive-dominance-epistasis model. For heights in the nursery test, while both non-additive and additive variances were important sources of genetic variation, the former decreased but the latter increased with age; among the non-additive genetic variance, the epistatic variance was much more important than the dominance variance. Different from the nursery traits, for traits in the field test, additive variance accounted for an average of 81% of the total genetic variance, whereas dominance variance explained most of the remaining genetic variance. Genetic parameters and selection efficiencies for three vegetative deployment strategies: deploying half-sib families (VD_FAM HS ), full-sib families (VD_FAM FS ), and multi-varietal forestry (MVF), were compared. Heritability estimates were moderate for VD_FAM HS and VD_FAM FS (0.61-0.72), high for MVF (>0.82) for the nursery heights, and high (>0.79) for the field traits for all strategies. Genetic correlations of volume at age 14 in the field test, the target trait for improvement, were strong (>0.85) with other field traits. Genetic correlations of VOL14 with the nursery heights were also strong (>0.71) at the half-sib and full-sib family levels, but were only moderate (>0.59) for MVF. Overall, practicing MVF is the most effective deployment strategy, yielding the highest genetic gains, followed by VD_FAM FS and VD_FAM HS , regardless of traits and selection methods. Furthermore, early selections for HT9 or for HT4-HT6 were very encouraging, resulting in higher gain in volume at age 14 on a per year basis.

Intra-specific variability in biomass partitioning and carbon isotopic discrimination under moderate drought stress in seedlings from four Pinus pinaster populations

“…The seedling phase is of primary importance in natural stands as mortality during the first year is the main selective factor. It has been suggested that biomass allocation at juvenile stages is a fundamental aspect of the diversification of pines (Strauss and Ledig 1985), and considering growth, genetic information from early testing can be used to enhance selection efficiency at maturity (Wu 1998;Weng et al 2008). …”

Genetic parameters for growth, wood density and pulp yield in Eucalyptus globulus

“…clone) statistical model, described as above for the CP data, has also been applied in the analysis of clonally replicated progeny tests of other forest tree species (e.g. Kumar 2006;Baltunis et al 2008;Callister and Collins 2008;Weng et al 2008). From the UC material, trait estimates of broad-sense heritability b H 2 were obtained by b…”

A comparative evaluation of the application of somatic embryogenesis, rooting of cuttings, and organogenesis of conifers

“…Conifer stem cuttings suitable for rooting are generally available only from plants that are too young to have demonstrated what kind of growth they are capable of over the long term. Because of the often poor correlation between juvenile and mature traits, proper testing generally requires at least about one-third to one-half the rotation age (Zobel 1981;Hodgetts et al 2001;Weng et al 2008). Juvenility can be prolonged a few years by repetitive pruning (hedging) or repeated cutting cycles (Bentzer 1993;Mason et al 2002;Mitchell et al 2004) but often not long enough to allow long-term field testing of the ortets to determine their suitability for clonal planting.…”