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We run logit models to explain the variability of Pinus radiata structural lumber in 71 second and third unpruned logs. The response variable was the proportion of lumber with a static modulus of elasticity greater or equal than 8000 MPa, pMSG8+, and the explanatory variables were log volume, branch index, largest branch, log internode index, wood basic density, and acoustic velocity. The average pMSG8+ volume was 44,30 % and 36,18 % in the second and third log respectively. Ten models were selected based on meeting statistical assumptions, their goodness of fit, and the statistical significance of their parameters. The best models (R2 - adj. > 0,75) included acoustic velocity (AV) as explanatory variable, which explained 56,25 % of the variability of pMSG8+. Models without AV presented goodness of fit ranging from 0,60 to 0,75 (R2 - adj.), and variables with the highest weight to explain the variability of pMSG8+ were volume, followed by wood basic density, branch index, and largest branch. It is possible to model pMSG8+ from log variables even when acoustic velocity is not available; however, this requires wood basic density models calibrated for the Pinus radiata growing zone. [ABSTRACT FROM AUTHOR]

Eucalyptus globulus Labill. is a short-fibre resource for pulp and paper production. Ten different E. globulus genotypes with varied pulpwood quality and chemical composition were evaluated under kraft pulping conditions. Characterisation of the wood and pulp samples by thioacidolysis indicated that the content of syringyl units in β-O-4 linkages (S-β-O-4) was distinct for the studied genotypes. The highest S-β-O-4 levels were detected in the samples with the lowest original lignin and highest glucan levels. This group of samples provided the pulps with the lowest final lignin content at higher yields. UV microspectrophotometric (UMSP) evaluation of the wood chips revealed that the samples with the lowest lignin levels have the lowest UV absorbances at 278 nm (A278 nm) in the secondary walls (S2). During kraft pulping, lignin from the S2 was dissolved, whereas lignins from the middle lamella and cell corner lignin was not removed not even for prolonged reaction periods, independently of the evaluated genotype. The A278 nm values of the S2 were significantly lower in the pulps from the genotypes with less original lignin content. [ABSTRACT FROM AUTHOR]

Variation and relationships among dasometric parameters, chemical composition, wood anatomy, pulpability (efficacy of kraft delignification), and handsheet properties were studied in fourteen 7-year-old Eucalyptus globulus clones grown in a clonal trial in the Bio-Bio Region, Chile. Three ramets per clone were sampled and all properties were measured for each tree. Results showed variations among clones for parameters associated with wood anatomy, chemical composition, pulpability, and handsheet properties, which are the basis for the improvement of these traits through clonal selection. However, our findings showed that tree size can negatively affect other traits such as basic density and other related parameters as wood consumption, tear index, specific bulk, and Gurley air resistance. Wood density and chemical composition were the most important parameters correlated with pulpability and handsheet properties. Therefore, future efforts in tree improvement should be focused on wood properties such as density, lignin, holocellulose, and α -cellulose contents. [ABSTRACT FROM AUTHOR]

Ganoderma australe is a basidiomycete responsible for a natural process of selective and extensive lignin degradation. Fatty acids, thiobarbituric acid reactive substances (TBARS), Fe3+-reduction and enzymatic activities were monitored in cultures of G. australe growing on Drimys winteri wood chips. Linoleic acid was de novo synthesized, and steadily increased during 12 weeks of cultivation. Part of the unsaturated fatty acids underwent peroxidation as TBARS accumulated with biodegradation time. TBARS accumulation was proportional to the wood weight and component losses. Manganese-dependent peroxidase and lignin peroxidase were not detected in the culture extracts, whereas laccase-induced oxidation of syringaldazine peaked after 2 weeks (104±9 μmol oxidized min−1 kg−1 of dry wood), subsequently decreasing. On the other hand, nonenzymatic Fe3+-reducing activity increased as a function of cultivation time and could be involved in the initiation of lipid peroxidation. [ABSTRACT FROM AUTHOR]

Abstract: The basidiomycete Ganoderma australe is responsible for a unique field biodegradation process resulting in completely white-rotted logs known as “palo podrido” in southern Chile. Although the field formation of “palo podrido” has been evaluated, attempts to reproduce this selective delignification in vitro have failed. In this study, a native wood species, Drimys winteri, was exposed to G. australe in soil-containing and control cultures in which vermiculite replaced soil. In the former, fungal growth and wood decay were more intense than in the vermiculite-supported cultures. However, lignin removal was not selective in either. In soil-containing cultures, diffusion and fungal translocation of Fe, Mn and Cu was significant, while the translocation of these metals was limited in vermiculite-containing cultures. Movement of soil nutrients into wood was relevant for improving fungal growth and wood decay, but was not a critical factor determining the selective biodelignification observed in field biodegradation of D. winteri by G. australe. [Copyright &y& Elsevier]

Ganoderma australe is a basidiomycete responsible for a natural process of selective and extensive lignin degradation. Fatty acids, thiobarbituric acid reactive substances (TBARS), Fe3+-reduction and enzymatic activities were monitored in cultures of G. australe growing on Drimys winteri wood chips. Linoleic acid was de novo synthesized, and steadily increased during 12 weeks of cultivation. Part of the unsaturated fatty acids underwent peroxidation as TBARS accumulated with biodegradation time. TBARS accumulation was proportional to the wood weight and component losses. Manganese-dependent peroxidase and lignin peroxidase were not detected in the culture extracts, whereas laccase-induced oxidation of syringaldazine peaked after 2 weeks (104+/-9 micromol oxidized min(-1) kg(-1) of dry wood), subsequently decreasing. On the other hand, nonenzymatic Fe3+-reducing activity increased as a function of cultivation time and could be involved in the initiation of lipid peroxidation.