Anatomy and lignin distribution of reaction wood in two Magnolia species |
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Authors: | N Yoshizawa A Inami S Miyake F Ishiguri S Yokota |
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Institution: | (1) Laboratory of Forest Products, Department of Forest Science, Faculty of Agriculture, Utsunomlya University, Utsunomlya, 321–8505, Japan, JP |
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Abstract: | Summary Anatomical features of reaction wood formed in two Magnolia species, M. obovata Thunb. and M. kobus DC. which are considered to be among the primitive angiosperms, were observed. In addition, the distribution of guaiacyl
and syringyl units of lignins in the cell walls of normal and reaction wood was examined using ultraviolet (UV)- and visible
light (VL)- microspectrophotometry coupled with the Wiesner and M?ule reactions. The two Magnolia species formed a tension-like reaction wood without possessing the typical gelatinous layer (G-layer) on the upper side of
the inclined stem or branch, in which a radial growth promotion occurred. Compared with the normal wood, the reaction wood
had the following anatomical features: (1) the secondary walls of fiber tracheids lacked the S3 layer, (2) the innermost layer of fiber-tracheid walls showed a small microfibril angle, a fact being similar to the orientation
of the microfibril angle of the G-layer in tension wood, and (3) the amounts of lignin decreased in the cell walls of fiber
tracheids, especially with great decrease in proportion of guaiacyl units in lignins. In addition, VL-microspectrophotometry
coupled with the Wiesner and M?ule reactions adopted in the present study showed potential to estimate the lignin contents
in the cell walls and the proportion of guaiacyl and syringyl units in lignins.
Received: 15 July 1998 |
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