【作者】 席恩华；

【导师】 赵广杰；

【作者基本信息】 北京林业大学 ， 木材科学与技术， 2012， 博士

【摘要】 为了弄清楚速生欧美杨107的木质部细胞分化模式以及在分化成熟过程中细胞形态比量、细胞壁层堆积、细胞壁化学成分分布和细胞壁力学性质的变化规律,本研究采用定量解剖学、计算机图形学、分形方法、偏光显微技术、激光共聚焦显微拉曼光谱技术和纳米压痕技术对活动期不同分化发育阶段木质部细胞的解剖特性、细胞壁壁层的堆积、细胞壁化学成分的分布、细胞壁力学性质和细胞形态比量及壁层的可视化进行了测定、分析和模拟。本研究得到以下主要成果和结论：1、从4月初到10月初,在整个活动期内欧美杨107形成层细胞和木质部细胞的解剖特征变化差异明显,各组织比量差异明显,木纤维的变化比导管分子显著,微纤丝角呈降低的趋势,结晶度呈增加的趋势,形成层解剖特征和木质部细胞的形态学相关性显著,外部气候因素和形成层及木质部细胞发育之间的相关性显著。2、在活动期内木质部细胞群图案的分形表征结果表明,横切面的分形维数呈增加的趋势,而弦切面的分形维数呈先降后增的趋势,横切面的分形维数大于弦切面的,横切面木质部细胞微观构造图案的分形维数与木质部细胞解剖特征的相关性显著。3、从偏光显微镜下细胞壁层出现明暗相间的分层图像判定,木纤维细胞次生壁在5月分化出了S1层和S2层,到了7月出现S3层,木纤维细胞次生壁S1层、S2层和S3层的厚度在活动期内都呈逐渐增加的趋势,晚材次生壁各壁层的厚度明显大于早材。4、在活动期内形成层和木质部细胞形态变化、细胞数量累积和木纤维细胞壁层堆积的可视化模拟,形象直观的展示了形成层和木质部细胞发育成熟过程中解剖特性的变化和细胞壁次生壁S层的堆积过程。5、在活动期内同一阶段木纤维细胞壁层不同部位化学成分分布结果表明,纤维素分布是S2>CML>CC,木素分布为CC>CML>S2；同一时期不同细胞次生壁木素和纤维素分布规律为导管分子>木纤维>薄壁组织；对活动期内不同阶段木纤维不同部位化学成分的分布发现,次生壁S2层、胞间层CML和细胞角隅CC的木素和纤维素分布规律为晚材>早材；导管分子次生壁木素和纤维素的分布规律也为晚材>早材。6、在活动期内木纤维细胞次生壁S2层、胞间层CML和细胞角隅CC处纵向弹性模量都呈增加的趋势；木纤维细胞次生壁S2层的纵向硬度呈增加的趋势,细胞角隅CC处呈下降趋势而胞间层CML纵向硬度变化不明显；木纤维细胞不同部位的纵向弹性模量大小为S2>CML>CC,硬度在早期大小为CC>CML>S2,在晚期的大小为S2>CML>CC；细胞壁纵向弹性模量与纤维索的浓度有着密切的关系,细胞壁的纵向硬度与木素的浓度有密切的关系。更多还原

【Abstract】 In order to make clear of xylem cell differentiation model, cell shape and accumulation, cell wall accumulation, chemical composition distribution of cell walls and their mechanical property of fast-growing Populusxeuram ericana cv.’74/76’ during the differentiation and mature process. The method of quantitative anatomy, computer graphics simulation technology, fractal method, polarized microscopic technology, confocal microscopy Raman spectra technology and nanoindentation technique were used to estimate and analyze and in different differentiation stage.The main achievements and conclusions were obtained as follows:1.From early April to early October, the changes of cambium and xylem cells anatomical characteristics were significantly of Populusxeuram ericana cv.’74176’during the active phase. The changes of tissue proportions were significantly, and the changes of wood fiber were more notable than that of vessel element. The microfibril angle presented a decrease trend and crystallinity showed an increase trend. The correlation of cambium anatomical characteristics and xylem cell morphology was notable. The correlations between external climatic factors and cambium and xylem cell were also significantly.2.The results of fractal characterization xylem cells group patterns showed that the fractal dimension of xylem cells cross section presented an increase trend and the changes of tangential section was first decreased then increased. The fractal dimension of cross section was large than that of tangential section. The fractal dimension of cross section xylem cells group has a remarkable correlation with xylem cells’ anatomical characteristics.3.It was determined that secondary cell wall of xylem cells differentiated S1 layer and S2 layer in May and S3 in July from cell wall appearing layers images with light and shade in the polarization microscope. The thickness of S1 layer, S2 layer and S3 layer were gradually increased during the active phase. The thicknesses of late wood secondary cell wall were significantly greater than that of early wood.4.The visualization of morphology and quantity changes of cambium and xylem cells and cell wall layers accumulation intuitively shows the cambium and xylem cells anatomical characteristics and the accumulation process of secondary cell wall during the development and maturation process.5.The results of chemical composition distribution in different position of wood fiber cell wall layers in the same stage during the active phase showed that the cellulose distribution was S2>CML>CC and the lignin was CC＞CML＞S2. It was found that lignin and cellulose distribution was vessel element> wood fiber＞parenchyma in the same stage. The lignin and cellulose concertration of late wood were larger than that of early wood in different position of wood fiber and vessel elemen.6.The longitudinal elastic modulus of secondary cell wall S2 layer, CML and CC were increased during the active phase. The longitudinal rigidity of secondary cell wall S2 layer was increased; however, the changes rigidities of CC and CML were not significantly. The longitudinal elastic modulus of xylem cells was S2>CML> CC, and the longitudinal hardness was CC> CML> S2. Cell wall longitudinal elastic modulus had a close relationship with cellulose concentration, and the longitudinal hardness had a close relationship with lignin concentration.更多还原