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

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 environment

Prediction of blackwood kraft pulps yields with wood NIR–PLSR models

Pulp yield is an important measure of pulpwood quality, which is used regularly by the pulp and paper industry for which the possibility of using rapid methods to predict pulp yield would be very useful for screening and quality control. This work addresses the prediction of Kraft pulp yield under standard identical conditions and targeted to a kappa number of 15, using near-infrared (NIR) partial least squares regression modelling. A total of 75 pulp samples of Acacia melanoxylon R. Br. (blackwood) with a pulp yield variation range of 47.0–58.2 % were used. Very good correlations between NIR spectra and pulp yield were obtained. Ten methods were used for PLS analysis (cross-validation with 62 samples), and an external validation was made with 13 samples. The 2ndDer pre-processed spectra coupling two wavenumber ranges from 9087 to 5440 and 4605 to 4243 cm−1 allowed the best model with a standard error of prediction of 0.4 %, a r2 of 98.1 %, and the ratios of performance to deviation (RPDTS) of 4.8. According to AACC Method 39-00, the present model is sufficiently accurate to be used in screening programs and in quality control (RPDCV = 6.9).info:eu-repo/semantics/publishedVersio