Analysis of Anatomical Characteristics and Chemical Composition of Pinus yunnanensis Lumber with Different Stem Forms

PurposeTo explore the differences in anatomical characteristics and chemical composition of straight stem and twisted stem Pinus yunnanensis lumber, and to lay a foundation for the subsequent analysis of the mechanism of stem shape variation of P. yunnanensis at the molecular level.

MethodsUsing the xylem of straight stem and twisted stem P. yunnanensis as materials, biological microscope and fluorescence microscope were used to observe the anatomical structures, at the same time, the main chemical composition was analyzed by colorimetry combined with Fourier transform infrared spectroscopy.

ResultsThe twisted stems P. yunnanensis lumber belonged to compression wood, and the cells in twisted compression wood (TCW) were notched, involute, rounded, and with increased and larger intercellular spaces in transverse sections, threaded crack in radial sections, and the number of traumatic resin channels increased obviously in tangential sections. There was no obvious difference between the straight stem P. yunnanensis lumber (S) and the twisted opposite wood (TOW) in the anatomical characteristics. Compared with TOW and S, the tracheids in TCW were shorter in length, narrower in width, smaller in lumen diameter, and thicker in cell wall of early wood, the lignin content increased significantly, the cellulose content decreased significantly, and the lignin accumulated in the outer layer of S2 layer and cell corner, while the lignin of TOW and S was evenly distributed in cell corner and cellular middle layer.

ConclusionThere are not only obvious differences in anatomical characteristics, but also in the content and distribution of cellulose, hemicellulose and lignin between straight and twisted stems of P. yunnanensis.