1992 Fiscal Year Final Research Report Summary
Studies on the Origin of Growth Stresses in Trees
| Project/Area Number |
02044067
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Nagoya University |
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Principal Investigator |
OKYYAMA Takashi Nagoya University, Asociate Professor, 農学部, 助教授 (00023482)
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| Co-Investigator(Kenkyū-buntansha) |
CURT C. Hassler University of West-Virginia, Associate Professor, 林学科, 助教授
ROBERT R. Archer University of Massachusetts, Professor, 教授
YAMAMOTO Hiroyuki Nagoya University, Assistant, 農学部, 助手 (50210555)
HATTORI Yoshiaki Kagoshima University, Associate Professor, 農学部, 助教授 (80180909)
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| Project Period (FY) |
1990 – 1992
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| Keywords | growth stress / cell wall / microfibril / microfibril angle / lignin / cellulose / reaction wood / gelatinous layer |
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| Research Abstract |
This project was set up to make clear the mechanism of growth stresses in trees.
The growth stresses were measured on the leaning stems of seven hard wood species. In the same time, the cross-sectional area of gelatinous fibers, microfibril angle, degree of crystallinity and contents of alpha-cellulose and lignin were correlated to the growth stresses.
The results can be summarized as follows.
1) Longitudinal growth stresses of the species which have gelatinous fibers in the upper side of a leaning stem : Large tensile stresses appeared in the same region where the cross-sectionalarea of gelatinous layers was large. Black Locust indicated an extremely large stress, above 70 MPa at the position where the gelatinous fibers were observed.
This result suggests that the gelatinous fiber produces a large tensile stress in the longitudinal direction.
2) Longitudinal growth stresses on the species which have no gelatinous fibers in the upper side of a leaning stem : (a) The smaller microfibril angl
… More
e is, the larger tensile stress becomes. This tendency was similar to that in the region of normal wood including soft wood. (b) The larger tensile stress is, the larger alpha-cellulose content is. (c) The tensile stress becomes larger as the crystallinity is higher. (d) The tensile growth stress had no correlation with the lignin content or had slightly negative correlation with it, including some soft wood species.
Those results coincide with the result of theoretical analysis basing on a reinforced compound cylinder model. Namely, during the cell wall maturation the contraction of microfibril are restricted mutually then tensile stress is produced in the longitudinal direction and the lignin deposition between gaps of cellulose microfibrils makes compressive stress in the lateral direction. The growth stresses in reaction wood are considered to be generated by actualizing of one of them.
The results of this research was presented to the IUFZRO World Congress and International Seminar on Structural Morphology held in France in August 1992. Less
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