Browsing by Author "Dr. Ilona Peszlen, Committee Chair"

Now showing 1 - 3 of 3

Development of a Wood Fiber Composite using Nonwoven Textile Technology
(2008-06-16) van Dyk, Hermanus Hendrik; Dr. Jag Kasichainula, Committee Member; Dr. Ilona Peszlen, Committee Chair; Dr. Perry Peralta, Committee Co-Chair; Dr. Pam Banks-Lee, Committee Member; Dr. Joel Pawlak, Committee Member
Environment and Genetic Effects on Wood Quality of Populus
(2005-08-10) Doungpet, Mayuree; Dr. Richard B. Hall, Committee Member; Dr. Myron W. Kelly, Committee Member; Dr. Perry N. Peralta, Committee Member; Dr. John A. Heitmann, Committee Member; Dr. Ilona Peszlen, Committee Chair
The purpose of the research was to investigate wood properties of new poplar clones from three different environments. Specific gravity, density, and anatomical properties were studied. Impacts of the cottonwood leaf beetle (Chrysomela scripta) on wood properties were investigated on two six-year-old clones in the first study. The results indicated that insect defoliation caused moderate to large decreases in annual growth over the first three years. Clones had different specific gravity and density for protected trees and constant values along the radius regardless of beetle attack. Fiber length was not affected by defoliation. Vessel number and diameter were impacted by defoliation and offsetting changes in vessel numbers and diameters partially cancel out changes in vessel area. Ray area was larger for unprotected trees; one clone responded to defoliation by producing more rays; meanwhile, the other produced fewer but larger rays. The second study dealt with wood properties of eight six-year-old Populus deltoides clones of two families grown under stressful site conditions. There were no differences in growth rate between the two families; however, specific gravity was significantly influenced by family and by clone. Fiber length was affected only by clone and radial position and correlated with growth rate. Clonal averages of fiber length were different closer to the bark suggesting that the earliest selection for fiber length should start after four or five years. The third study analyzed wood variation for four-year-old Populus deltoides trees with exceptional specific gravity and growth rate values. There were significant differences among trees in fiber length and vessel area but not in vessel numbers, vessel diameter, and in ray numbers. The age of the cambium significantly affected all wood properties. The fastest growing tree with high specific gravity had the longest fibers, the highest ray numbers but low vessel area, vessel number, and low vessel diameter representing an unusual combination of traits. Results indicate that trees with similar growth rates can have wide variation in vessel area and that exceptionally fast-growth tree can be achieved with low vessel area.
Fungal Degradation Properties of Young Small Diameter Genetically Modified Quaking Aspen (Populus tremuloides)
(2008-10-31) Giles, Richard Lee; Dr. Perry Peralta, Committee Co-Chair; Dr. Ilona Peszlen, Committee Chair; Dr. Larry Grand, Committee Member; Dr. Hou-Min Chang, Committee Member
Three studies were conducted to evaluate the fungal degradation properties of young transgenic aspen trees (Populus tremuloides). The first study focused on development of methods of decaying small diameter tree samples. The second and third studies focused on the mass loss differences and cellulose and lignin degradation between trees with different lignin types and contents. In the first study, two methods for rapid laboratory fungal decay tests of very young small diameter (5-15 mm) hybrid poplar (Populus nigra x Populus maximowiczii), yellow poplar (Liliodendron tulipifera), and willow (Salix sp.) trees were examined using the white rot fungi Trametes versicolor and Ceriporiopsis subvermispora. An agar plate method and a modified soil-agar block method were compared using non-standard size stem parts. The agar plate method did not prove to be suitable for testing materials when limited numbers of samples are available because of the extremely high variation of mass loss values. Mass loss using the modified soil-agar block technique was comparable to established methods for small and large blocks using extended colonization periods. In the second study, one-year old quaking aspen (Populus tremuloides) trees including a control wild type aspen and three lines of transgenic trees were analyzed for resistance to lignin selective white rot fungal decay. The transgenics had reduced lignin content through transfer of an antisense -4CL gene, changed syringly/guaiacyl ratio through insertion of a sense CAld5H gene, and modified lignin content and syringyl/guaiacyl through simultaneous insertion of -4CL and CAld5H genes. Mass loss was used to examine differences between genetic lines. The small diameter transgenic trees were decayed using lignin selective white rot fungus Ceriporiopsis subvermispora. A modified soil-agar block method was used with a forty day colonization time. The transgenic lines with higher S/G lignin ratio exhibited a higher mass loss percentage compared to the wild type and other transgenic lines. In the third study, the transgenic lines were analyzed for resistance to three types of fungal decay. The small diameter transgenic trees were tested using simultaneous white rot fungus Trametes versicolor, lignin selective white rot fungus Ceriporiopsis subvermispora and a brown rot fungus Poria placenta. A modified soil-agar block method was used to decay the samples. Near infrared spectroscopy and chemical analysis determined loss of cellulose and lignin variations between transgenic genotypes. Near infrared transmittance was successful in predicting the cellulose and lignin percentages of the decayed material. The reduced lignin content lines did not affect the rate of lignin decay for all fungi tested. Lignin decay rates were reduced by the increased S/G ratio lines for all fungi tested.