Bamboo node is a specialized structure that has great effect on both bamboo growth, physical-mechanical properties, and its utilization. Compact structure and particularly high hardness make bamboo node very difficult for slice specimens preparation. In this study, in order to explore the differences in anatomical characteristics of bamboo nodes' vascular bundles among species, 3D structures of bamboo nodes in four bamboo species (Bambusa emeiensis, , , and ) were reconstructed by the micro-CT technique. The characteristics of vascular bundles were comparatively analyzed based on the CT images. The results showed that the vascular bundle morphology of and changed significantly from node to internode. The areas of fiber cells in the middle part along the radial direction of bamboo culm wall has the largest area (0.204 mm), followed by the inner part (0.151 mm) and the outer part (0.072 mm). The area of transport tissue in the inner part along the radial direction of bamboo culm wall has the largest area (0.046 mm), followed by the middle part (0.028 mm) and the outer part (0.002 mm). The bending vascular bundles in bamboo node can be divided into thick and thin types. The average thickness of the thin bending vascular bundles among the four bamboo species was 125 μm, with the thinnest value of 109 μm. While, the average thickness of thick bending vascular bundles was 265 μm, with the thickest value of 335 μm. The number proportion of thick vascular bundles was 60.8%, 42.5%, 32.9%, and 10.7% for , Bambusa emeiensis, , and . This study set up a nondestructive and efficient method for 3D anatomical structure characterization of bamboo node and the variation analysis in bamboo nodes’ vascular bundles.

中文翻译：

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X射线显微计算机断层扫描无损分析竹节维管束物种间变异

竹节是一种特殊的结构，对竹子的生长、物理力学性能及其利用都有着重要影响。致密的结构和特别高的硬度使得竹节的切片标本​​制备非常困难。本研究为了探讨不同物种间竹节维管束解剖特征的差异，采用显微CT技术重建了四种竹种（峨眉竹、、、、）竹节的3D结构。根据CT图像对维管束的特征进行对比分析。结果表明，从节到节间，维管束形态发生了显着变化。竹秆壁径向中部纤维细胞面积最大（0.204 mm），其次是内部（0.151 mm）和外部（0.072 mm）。竹秆壁径向内侧输送组织面积最大（0.046 mm），其次是中部（0.028 mm）和外侧（0.002 mm）。竹节内弯曲维管束可分为粗型和细型。 4个竹种的细弯曲维管束平均厚度为125μm，最薄处为109μm。而粗弯曲维管束的平均厚度为265 μm，最厚可达335 μm。 、峨眉竹、 、 粗维管束数比例分别为60.8%、42.5%、32.9%、10.7%。本研究建立了一种无损、高效的竹节3D解剖结构表征和竹节维管束变异分析方法。