Changes in the cellulose crystallinity of moso bamboo cell walls during the growth process by X-ray diffraction techniques

Abstract

We investigated the changes in cellulose crystallinity in the cell walls of moso bamboo (Phyllostachys pubescens Mazel) during the growth process. Changes in crystallinity in bamboo cell walls were traced along the longitudinal and radial directions using flat-sawn specimens obtained from each internode using X-ray diffraction measurements. Cellulose crystallinity in cell walls in the same culm was higher around the base of the bamboo culms in less than 10 days after the emergence of bamboo shoots, while the upper internodes remained lower in crystallinity. Thereafter, crystallinity in the upper internodes of bamboo culms became higher. This suggests that cellulose crystallinity within bamboo cell walls has gradually increased from the base to the top with the elongation of the internode during the growth process of bamboo shoots. In addition, cellulose crystallinity in cell walls increased particularly in the outer part of the bamboo culms in all internodes. Moreover, increases of crystallinity occurred after elongation growth of internodes. It is considered that increases in crystallinity in the outer portion of each internode are one of the countermeasures of bamboo culms against increased bending moment due to the elongation growth.