Evaluation of Wood Properties of Genetically Modified Trees

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Title: Evaluation of Wood Properties of Genetically Modified Trees
Author: Saralde, Teofisto Cis Jr.
Advisors: Ilona Peszlen, Committee Co-Chair
Myron W. Kelly, Committee Member
Perry N. Peralta, Committee Co-Chair
Tasnim Hassan, Committee Member
Bohumil Kasal, Committee Member
Abstract: Two related studies were conducted for the evaluation of wood properties of genetically modified loblolly pine (Pinus taeda): first in terms of mechanical properties and then for shrinkage properties. Another study focused on the development of methods for the evaluation of the mechanical properties of small young trees. In the first study, the effect associated with genetic modification of loblolly pine was evaluated by comparing the mechanical properties of lumber from trees deficient in cinnamyl alcohol dehydrogenase (CAD) enzyme with those from wild-type trees. Small clear wood specimens were tested in static bending, compression parallel and perpendicular to the grain, tension perpendicular to the grain, and shear parallel to the grain. Results indicated that there was no significant difference between the two genotypes for all mechanical properties measured. Consequently, partially CAD-deficient loblolly pine has no significantly altered mechanical properties. In the second study, partially CAD-deficient and wild-type loblolly pine were studied for shrinkage properties. Pie-shaped samples for the determination of radial and tangential shrinkages were cut from logs. The method allows for the measurement of shrinkage for different wood types and for correction due to the effect of growth ring curvature. Results showed that radial, tangential, and longitudinal shrinkages of juvenile wood were significantly different from the corresponding shrinkages of mature wood. In addition, no significant difference was observed in shrinkage properties between partially CAD-deficient and wild-type loblolly pine. The third study dealt with development of a method for evaluating mechanical properties of small young trees in static bending and compression parallel to the grain utilizing the full cross section of the tree. In the absence of an established test method, the approach was to start from ASTM standard test of small clear wood. The experiment was designed as a replicated 5-level Graeco-Latin square with tree, stem location, dimensional ratio of the test specimen, and test strain rate as factors. Span-to-depth ratio for bending, length-to-diameter ratio for compression, and strain rates were established as test variables based on the analysis of the result. Along the tree height, there was no significant difference in mechanical properties starting from the base to 0.45 of the total height of the tree.
Date: 2007-03-14
Degree: MS
Discipline: Wood and Paper Science
URI: http://www.lib.ncsu.edu/resolver/1840.16/1043

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