摘要
用光学显微镜和扫描电镜观察比较了马尾松(Pinus massoniana)正常木与应压木的结构差异。研究结果表明:马尾松应压木从早材到晚材呈缓变,管胞在横切面上除生长轮分界处的两侧外均为圆形,管胞之间具明显的胞间隙;管胞的次生壁仅有 S_1和 S_2两层;次生壁上螺纹间隙和螺纹裂隙都很明显,并与 S_2层微纤丝平行。此外,还初步讨论了应压木形成的可能机理。
Anatomical differences between normal wo od and compression wood of masson pine(Pinus massoniana)were studied by means of light and scanning electron microscope.The results show that the normal wood is narrower han the compression wood in growth ring width.The transition from earlywood to latewood is abrupt in normal wood in contrast to the gradual transition in compression wood.In transverse section,normal wood tracheids appear more or less square and rectangular,whereas compression wood tracheids are round in shape with the exception of those at the vicinity of growth ring boundary.In consequence,intercellular spaces are prominent at the junction of tracheids in compression wood.Furthermore,the secondary walls of compression wood tracheids consist of only two layers,S_1 and S_2,in compa- rison with the three layers in normal wood.Helical cavities or checks present only in compres sion wood,spiraling around the tracheid in the same direction as the cellulose microfibrils. Finall(?) the factors responsible for the formation of compression wood are discussed as well.
关键词
马尾松
正常木
应压木
Pinus massoniana
Normal wood
Compression wood
