Determination of tree to tree variation in syringyl/guaiacyl ratio of Eucalyptus globulus wood lignin by analytical pyrolysis

High syringyl/guaiacyl ratios (S/G ratios) are advantageous for pulping. An alytical pyrolysis was applied to Eucalyptus globulus wood to measure S/G r atios and assess its potential in forest breeding programmes. Samples were collected from five trees of two provenances grown in three sites. After pe ak assignment, relative peak areas were calculated for carbohydrate, guaiac yl and syringyl type degradation products. Lignin derived products account on average for 21% of the total identified area. The average S/G ratio of t rees was 2.0, ranging from 1.5 to 2.6. The analysis of variance for the S/G ratios showed that provenance and tree were highly significant sources of variation accounting for 48 and 27% of the variation, respectively. Site ha d no influence but 'site x provenance' interaction was significant and acco unted for 16% of the variation. The error associated with the method repres ented only 6% of the variation. Analytical pyrolysis proved reproducible an d sensitive for the measurement of the natural variability of E. globulus w ith regard to lignin composition. The pyrolytic determination of the S/G ra tios is recommended as an evaluation trait in breeding programmes for pulpw ood production. (C) 1999 Elsevier Science B.V. All rights reserved.