Genetic improvement for pulpwood and peeled veneer inEucalyptus nitens

Abstract

Genetic improvement of wood properties affecting the quality of pulpwood and peeled veneer products is of general interest to tree breeders worldwide. If the wood properties of Eucalyptus nitens (H. Deane & Maiden) Maiden are under genetic control and the correlations between them are favourable, it may be possible to breed to simultaneously improve the plantation resource for both products. Acoustic wave velocity (AWV) measured in standing trees can predict wood stiffness, basic density, and kraft pulp yield (KPY) and therefore has the potential for use in tree breeding programs. From an E. nitens progeny trial in Tasmania, 540 trees were selected for rotary peeling. Of the wood properties assessed, there were significant differences among races in diameter, stem straightness, standing-tree, log, and billet AWV, and near infrared predicted cellulose content (CC). All traits displayed significant within-race genetic variation, and genetic correlations between AWV and veneer sheet modulus of elasticity (MOE) and between AWV and KPY and CC were strongly positive and highly significant. A similar relationship was found between veneer sheet MOE and KPY and between diameter at breast height and veneer sheet MOE. Basic density was genetically correlated with AWV and veneer sheet MOE. Results indicate that it should be possible for breeders to simultaneously improve properties in pulpwood and peeled veneer products and that AWV measured in the standing tree shows promise as a breeding selection criterion for both pulpwood and peeled veneer products.

Acoustic Wave Velocity as a Selection Trait in Eucalyptus nitens

“…Notably, the AWV of the Southern race was higher than the other two Central Victorian races across all sites. This is consistent with the Southern race's previously reported superior performance for several traits relevant to veneer [24], as well as solid wood and pulpwood [35] traits.…”

“…The Tarraleah trial was harvested in two stages, three replicates at age 13 years and three replicates at age 14 years, to undertake a sawmilling and rotary-peeling study respectively [24,33]. [23,24] 181 (14) # 127 (19) 414 (19) 417 (19) Number of families for core BD (age in years) [34] 104 (9) # N/A 112 (9) # N/A Number of families for wedge BD (age in years) [23,24] Historic and recently-collected AWV, basic density and diameter at breast height (DBH, 1.3 m) data were analysed (Table 4). A Fakopp TM microsecond (single pass) timer was used to assess AWV, with probes located in a northerly position at a height of 0.5 m and 1.7 m. The probes were driven into the wood to a depth of approximately 12 mm below the bark, the upper probe pointing down and the lower probe pointing up in a vertical plane at approximately 45 degrees.…”

“…Assessment of AWV was undertaken on all families at Florentine and Meunna on one healthy tree per family plot at age 19. At Tarraleah, AWV data were collected on a sample of families felled as part of the sawmilling and peeling studies conducted at ages 13 and 14 respectively [24,25,33]. Trees in this trial were selected on the basis of good stem straightness and minimum/maximum size criteria for sawn timber and veneer processing.…”

“…Previous studies conducted on a single Tasmanian E. nitens progeny trial [24,25] revealed significant genetic variation in AWV, as well as significant and favourable genetic correlations between AWV in standing trees and the commonly-assessed pulpwood selection criteria -DBH, wood basic density and kraft pulp yield. Given the importance of the predictive capacity of standing tree AWV, the paucity of genetic studies of AWV in eucalypts, and the unique opportunity to assemble harvest-age measurements of growth, AWV and basic density from multiple, pedigree-connected trials established in Tasmania, the study aims to directly assist those engaged in E. nitens solid-wood breeding by addressing three key questions:…”

“…Acoustic wave velocity taken from standing trees has only recently become a selection criterion of interest [22][23][24][25]. [26] Cool-moist Warm-moist Warm-moist Cool-moist Acoustic wave velocity is correlated with modulus of elasticity (MOE) [25,27], a key structural characteristic which is indicative of end-product stiffness [23,28].…”