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ABSTRACT
Mutant loblolly pine trees that are partially deficient in cinnamyl alcohol dehydrogenase (CAD) have been studied as a possible new source of pulpwood. Young (4- and 6-year-old) partially CAD-deficient pine trees are ˜20% more easily delignified (pulping and bleaching) and provide similar pulp yields to that of similarly aged normal pines grown on the same plots. Bleached pulp from a 6-year-old partially CAD-deficient pine tree displayed better strength properties than the same age normal pine tree; this probably reflects the milder pulping conditions needed in the case of the partially CAD-deficient tree. Studies also were conducted on a limited number of 14-year-old trees from a different genetic background. In contrast to the results with young trees, no real differences in ease of delignification, pulp yields, bleached pulp strength properties, and wood specific gravities were observed with the 14-year-old trees. There would likely be no penalty if partially CAD-deficient trees were used for lumber products. The rapid growth of partially CAD-deficient trees could make them a valuable pulpwood.
ACKNOWLEDGMENTS
The IPST studies were supported by National Research Initiative US Department of Agriculture research grant # 99-35103-8365. Ms. A. White-Hughes, Mr. W. C. Jackson, and Mr. M. Turner performed the pulping and bleaching studies at IPST; their assistance is gratefully acknowledged. We would also like to thank International Paper Company for their cooperation in obtaining tree samples and the donation of six trees for our study. We are indebted to Mr. Alexander Clark at the USDA Forest Service Laboratory, Athens, Georgia, for providing the specific gravity measurement data on the 14-year-old trees.