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

Abstract

Genetic variation and co-variation among the key pulpwood selection traits for Eucalyptus globulus were estimated for a range of sites in Portugal, with the aim of improving genetic parameters used to predict breeding values and correlated response to selection. The trials comprised clonally replicated full-sib families (eight trials) and unrelated clones (17 trials), and exhibited varying levels of pedigree connectivity. The traits studied were stem diameter at breast height, Pilodyn penetration (an indirect measure of wood basic density) and near infrared reflectance predicted pulp yield. Univariate and multivariate linear mixed models were fitted within and across sites, and estimates of additive genetic, total genetic, environmental and phenotypic variances and covariances were obtained. All traits studied exhibited significant levels of additive genetic variation. The average estimated within-site narrowsense heritability was 0.19±0.03 for diameter and 0.29± 0.03 for Pilodyn penetration, and the pooled estimate for predicted pulp yield was 0.42±0.14. When they could be tested, dominance and epistatic effects were generally not statistically significant, although broad-sense heritability estimates were slightly higher than narrow-sense heritability estimates. Averaged across trials, positive additive (0.64± 0.08), total genetic (0.58 ±0.04), environmental (0.38±0.03) and phenotypic (0.43±0.02) correlation estimates were consistently obtained between diameter and Pilodyn penetration. This data argues for at least some form of pleiotropic relationship between these two traits and that selection for fast growth will adversely affect wood density in this population. Estimates of the across-site genetic correlations for diameter and Pilodyn penetration were high, indicating that the genotype by environment interaction is low across the range of sites tested. This result supports the use of single aggregated selection criteria for growth and wood density across planting environments in Portugal, as opposed to having to select for performance in different environments.

Genetic parameters of growth, straightness and wood chemistry traits in Pinus pinaster

“…4 were assumed to follow normal distributions with means and variances defined by: where 0, I, s 2 a and s 2 e are defined as above (observations on different ramets of a clone were treated as repeated measurements on a single genotype, therefore A is the matrix of relationships among individual genotypes as mentioned before); s 2 f is the non-additive genetic variance among full-sib families, and s 2 c is the non-additive variance among clones within full-sib families. This full model was used after excluding from the dataset the families with only one genotype, as they do not allow the estimation of dominance effects (Costa e Silva et al 2009). Thus the full model was fitted for 36 families representing 143 clones and 705 phenotypes out of the 892 trees.…”

ESTRATÉGIAS NA SELEÇÃO SIMULTÂNEA DE VÁRIOS CARACTERES NO MELHORAMENTO DO <i>Eucalyptus</i>

“…A partir desses resultados, infere-se que não ocorreu mudança expressiva na classificação das progênies nos ambientes avaliados para a característica DB. Na literatura existem relatos da ocorrência de interação progênies x ambientes para essa característica, em que foram obtidas altas estimativas de correlações entre o desempenho médio das progênies nos vários locais (MUNERI e RAYMOND, 2000;KUBE et al, 2001;COSTA e SILVA et al, 2009). Em outros trabalhos, essa interação não foi significativa (POKE et al, 2006;LIMA et al, 2011).…”

Seleção de progênies de eucalipto pelo índice Z por MQM e Blup

“…Em seguida, é consumida e, consequentemente, menor quantidade de reagentes por unidade de tempo tem que ser recuperada, o que leva a um aumento na capacidade de produção da fábrica (Borralho et al, 2007). Estimativas de correlação entre DAP e RD de 0,12 a 0,23 foram obtidas por Costa e Silva et al (2009) e Hamilton et al (2009. Assim, uma estimativa de correlação alta e positiva entre os caracteres de crescimento e RD, apesar de ideal, não tem sido encontrada nos trabalhos realizados.…”