Original article

Genetic variation and parental performance under inbreeding for growth in Eucalyptus globulus

¹ Centro de Estudos Florestais, Departamento de Engenharia Florestal, Instituto Superior de Agronomia, Universidade Técnica de Lisboa, Tapada da Ajuda, 1349-017 Lisboa Codex, Portugal
² Centro de Matemática e Aplicações, Departamento de Matemática, Instituto Superior Técnico, Universidade Técnica de Lisboa, Avenida Rovisco Pais, 1049-001 Lisboa, Portugal
³ University of Queensland, School of Land, Crop and Food Sciences, St Lucia, 4072, Queensland, Australia
⁴ School of Plant Science and Cooperative Research Centre for Forestry, University of Tasmania, Private Bag 55, Hobart, Tas., 7001, Australia

^* Corresponding author: jces@isa.utl.pt

Received: 1 June 2009
Accepted: 21 December 2009

Abstract

• We aimed to better understand the genetic architecture of growth in E. globulus undergoing inbreeding by comparing families from selfing (SELF), open pollination (OP) and unrelated polymix crossing (POL) of common parents. Stem diameter at breast height (DBH) was assessed at 4, 6 and 10 years after planting in a field trial.

• The OP heritability was overestimated at an early age relative to the POL heritability.

• No significant correlations were found between the SELF and POL parental effects, indicating substantial non-additive genetic variation under inbreeding. The OP family effects were better correlated with the SELF than the POL population, and only at age 10 years, after substantial mortality of inbred progeny has occurred, was the positive correlation between OP and POL families significantly different from zero.

• The estimated dominance variance arising from inbreeding was nearly 10-fold greater than the dominance variance associated with random mating and the additive variance, and appeared to be a major contributor to the variation in inbreeding depression amongst selfed families.