A nondestructive method using X-ray micro computed tomography for variation analysis of bamboo nodes’ vascular bundle among species

Abstract

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, Phyllostachys edulis, Pleioblastus amarus, and Bambusa rigida) 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 Pleioblastus amarus and Bambusa rigida 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 mm2), followed by the inner part (0.151 mm2) and the outer part (0.072 mm2). The area of transport tissue in the inner part along the radial direction of bamboo culm wall has the largest area (0.046 mm2), followed by the middle part (0.028 mm2) and the outer part (0.002 mm2). 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 rigida, Bambusa emeiensis, Pleioblastus amarus, and Bambusa rigida. 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.