Genetic correlations among pulpwood and solid-wood selection traits in Eucalyptus globulus

Abstract

Eucalyptus globulus is widely grown for pulpwood production in temperate regions of the world. However, there is increasing interest in using it for solid-wood products. We studied the genetic architecture of key pulpwood and solid-wood selection traits using two E. globulus progeny trials in a high rainfall area (wet) of Tasmania and a previously studied trial in a low rainfall area (dry). These trials were established using open-pollinated families from native trees sampled from 13 subraces. We assessed traits in common [diameter at breast height (DBH) and wood basic density (BD)], and specific to pulpwood [Kraft pulp yield (KPY)] and solid-wood [stem straightness and acoustic wave velocity (AWV)] breeding. Significant genetic variation was found for all traits. Strong GxE was detected for DBH across the wet and dry sites, but little for BD and KPY. At the wet sites we show a positive genetic correlation between DBH and KPY, but not between DBH and BD. Subrace and family within subrace correlations between KPY and BD were significant but in opposite directions. We confirm previous reports of significant positive genetic and phenotypic correlations between KPY and AWV. A positive genetic correlation between stem straightness and DBH was detected, and subraces with straighter stems tended to have higher KPY. In general, correlations between most solid-wood and pulpwood traits were favourable, suggesting that past selection for pulpwood traits had neutral or favourable effects on many key solid-wood traits. We conclude that breeding for solid-wood and pulpwood are relatively compatible.