Genetic gain from selection for rooting ability and early growth in vegetatively propagated clones of loblolly pine

Abstract

A successful clonal forestry program for loblolly pine based on rooted cutting technology needs to consider selection for both rooting ability and subsequent field growth. Rooting ability and second-year height were assessed in more than 2,000 clones from 70 full-sib families of loblolly pine. The bivariate analysis of rooting ability from five rooting trials and field growth from six field trials allowed for estimation of the genetic covariance between rooting ability and second-year height for parental effects, full-sib family effects, and the total genetic value of clones within full-sib family. There was a positive genetic relationship between rooting ability and second-year height at all three genetic levels. The genetic correlation at the parental level between rooting ability and second-year height b r B GCA ð Þ was 0.32. At the full-sib family level, the genetic correlation between traits b r B FS ð Þ was 0.39. The correlation of total genetic values of clones for rooting ability and second-year height b r B TG ð Þ was 0.29. The genetic gain in rooting ability and second-year height was estimated for a number of deployment options based on various selection scenarios using the best linear unbiased prediction (BLUP) values from the bivariate analysis. The deployment strategies compared were (1) half-sib family deployment, (2) full-sib family deployment, and (3) clonal deployment. Moderate to high family and clonal mean heritabilities, moderate to high type B genetic correlations, and substantial among-family and among-clone genetic variation indicate the potential for increasing rooting efficiency and improving growth.

Unraveling Additive from Nonadditive Effects Using Genomic Relationship Matrices

“…This phenomena has been postulated theoretically (e.g., Falconer and Mackay 1996, p. 126) and observed in multiple studies (Wei and Van Der Werf 1993;Winkelman and Peterson 1994;RodriguezAlmeida et al 1995;Pante et al 2002). In addition, when pedigree-based models included nonadditive effects, the conclusions were not different from what has been commonly observed that nonadditive effects represent a small fraction of the total genetic variation (Isik et al 2003;Costa E Silva et al 2004;Baltunis et al 2007;Araujo et al 2012).…”

“…Field data from a single experimental trial from the CCLONES population (see Baltunis et al 2007 andResende et al 2012a for details) was used in this study. The response variable total tree height (HT, m) was used.…”

“…Thus, clonal populations are an alternative to explore the full genetic architecture in these species (Foster and Shaw 1988). Several studies aimed at partitioning genetic variance into its various components detected small dominance and negligible epistatic effects (Foster and Shaw 1988;Mullin et al 1992;Wu 1996;Isik et al 2003Isik et al , 2005Costa E Silva et al 2004, 2009Baltunis et al 2007Baltunis et al , 2008Baltunis et al , 2009Araujo et al 2012). These results do not necessarily imply that such effects are not important.…”

Using semidefinite programming to optimize unequal deployment of genotypes to a clonal seed orchard

“…The population was derived by controlled crossing among 32 selected parents from the Lower Gulf Elite Population, consisting of 22 fieldselected F 0 plus trees and 10 selected F 1 progeny. These parents were crossed in a partial diallel mating design, and the progeny propagated for field testing as rooted cuttings (Baltunis et al 2007a, b). For this case study, we developed the SDP to optimize the selection of a grafted elite seed orchard with a total of N =2,000 ramets, based on the published 6-year height EBVs for 861 of the candidate genotypes.…”

Clonal variation in Scots pine (Pinus sylvestris) and in transgenic silver birch (Betula pendula)

“…They found out that the clonal testing of full-sib families increased the expected genetic gain for volume faster than seedling testing. Baltunis et al (2007) studied the genetic gain of two positively correlated traits of loblolly pine, rooting ability and early height growth, when four selection intensities were used. Both traits showed large clonal variation and, as they were positively correlated, selection of either of them was expected to bring gain in the other.…”