紫外线照射对毛竹茎秆细胞壁超微结构及色泽变化的研究

ULTRASTRUCTURE OF CELL WALLS AND COLOUR CHANGE IN PHYLLOSTACHYS PUBESCENS CULM AFTER THE TREATMENT OF ULTRAVIOLET IRRADIATION

应用光学显微镜、扫描电子显微镜和色度计 ,研究了毛竹竹材表面经紫外线照射后细胞壁的破损程度 ,具木质素组织分解深度以及颜色变化等规律。结果表明 :经紫外线照射后 ,在竹材横切面上 ,纤维细胞壁的分解始于次生壁各层连接处 ,接着是细胞角隅处和复合中层 ,最后纤维细胞壁全部被分解消失。薄壁组织细胞壁的复合中层先被分解 ,随后细胞壁分解变薄、坍塌和消失。竹秆壁表面的分解 ,最初从表皮细胞的短细胞开始 ,然后扩展到其它表皮细胞。根据木质素的显色反应显示 ,紫外线照射竹材样品 4 0d时 ,薄壁组织比纤维组织分解得更深 ,其中前者为 5 90 μm ,而后者只有 1 4 6μm。另外 ,经紫外线照射后的竹材样品 ,其横切面上的颜色和亮度变化最大 ,径向切面次之 ,竹秆壁表面变化最小。本文还讨论了经紫外线照射后 ,竹材中具薄壁组织比纤维组织分解更深的原因 ,以及样品

Deterioration of culms of Phyllostachys pubescens after the treatment of ultraviolet irradiation was investigated by means of a scanning electron microscope (SEM), light microscope and colorimeter. SEM observation on the cross sections of the bamboo showed that the deterioration in the fibers started in inter-layers of secondary walls followed by the cell corners and the middle lamellae. While the deterioration in the parenchyma cells began from the cell corners followed by the middle lamellae. Consequently, all the cell walls were eroded. In terms of the colour reaction after 40 days of UV irradiation on the cross sections of bamboo surface, it was further determined that the deterioration reached a depth of 590 μm in the parenchyma and 146 μm in fiber from the surface. In addition, this study noticed that there exited sharp difference in colour and brightness after the treatment with the UV irradiation along the different directions. Finally, the mechanism of causing the structural changes was discussed as well.