东北常见树种木材形成早期组织波谱特征差异分析

Comparative Analysis of Spectroscopy Features of Early-Stage Wood Forming Tissue in Common Tree Species in Northeast,China

【目的】研究东北主要商品材树种木材形成早期组织的化学特征及其在树种间的差异,为揭示树木生长过程中木材细胞壁的自组装行为和木材形成的分子机制提供科学依据。【方法】选取东北10种重要商品材树种,采集木材形成早期组织,利用红外光谱和X射线衍射技术分析木材形成早期组织的波谱特征。【结果】红外光谱差别主要在波数900～2 000 cm^(-1)之间的指纹区域。针叶树种木材中波数1 735 cm^(-1)附近由木聚糖乙酰基C O伸缩振动引起的吸收峰相对强度显著小于阔叶树种木材。针叶树种木材中1511cm^(-1)处表征苯环碳骨架振动的吸收峰较明显,尤其是云杉和落叶松。针、阔叶树种木材在波数1 630～1 660 cm^(-1)之间均出现不同强度的吸收峰,峰形较宽,该峰归属为蛋白质肽段中氨基化合物振动引起。红外光谱二阶导数处理后,针叶树种木材在波数1 266 cm^(-1)处有明显吸收峰,阔叶树种木材中并未发现,该峰归属为愈创木基环加CO伸缩振动。而阔叶树种木材在1245cm^(-1)处有较明显吸收峰,该峰由木质素紫丁香基环振动引起。多数树种木材X射线衍射图谱I002有较强的衍射峰,但Iam的衍射峰并不明显,尤其是阔叶树种木材。因此推测木材形成早期组织中纤维素的晶型、晶胞或晶区大小与成熟木材不同。【结论】针、阔叶树种木材形成早期组织中木质素和半纤维素的沉积过程有所差别,这有助于揭示木材形成过程中化学成分和结构的变化规律。

【Objective】This paper aimed to reveal the chemical features in early-stage wood forming tissue of some main commercial wood species,and its differences among species were also analyzed. 【Method 】Both FTIR and XRD were employed to investigate the spectrum properties in early-stage wood forming tissue of ten commercial tree species.【Result】The results showed that the principal differences were found in finger region with the wave number from900 cm^-1 to 2 000 cm^-1 of FTIR. The peaks at 1 735 cm^-1 for unconjugated C O in xylans exhibited significantly lower relative intensities in softwoods than hardwoods species. The absorption bands at 1 511 cm^-1 for aromatic skeletal in lignin showed obviously in softwoods,especially in Larix gmelinii and Picea jezoensis. Both in softwoods and hardwoods,the different intensities and broad peaks at 1 630- 1 660 cm^-1 attributed to vibration of amide compounds in protein peptides.After infrared spectroscopy treated by second derivative,conifer showed significant peaks at 1 266 cm^-1 due to ring plus C O vibration in guaiacyl but not in hardwood. However,hardwood showed obviously peaks at 1 245 cm^-1 which resulted from syringyl ring and C—O stretch I lignin. X-ray diffraction spectrogram showed the relative high intensities at I002,but no obvious peaks at Iam,especially in hardwood. Therefore,it is suggested that the differences should be exist in crystal form, crystal cell or size of crystalline region between early-stage wood forming tissue and mature wood.【Conclusion】The results indicated that there were differences in lignin and hemicellulose deposition in wood formation between softwoods and hardwoods. All these would be helpful to reveal the change patterns of chemicals and structure in wood cell wall development.