A topochemical and semiquantitative study of the lignification during ageing of bamboo culms (Phyllostachys viridiglaucescens)

The lignification of Phyllostachys viridiglaucescens (Carr.) Riv. & Riv. during ageing was studied topochemically by means of UV microspectrophotometry. The study revealed that p-coumaric and ferulic acids are widely distributed in P. viridiglaucescens and that their content is dependent on the anatomical location and the differentiation phase. The lignin in the epidermal cell wall is deposited early in the development and does not increase with age. This is in contrast with the fibres and the ground parenchyma cells where an increasing trend in lignification during the first year is shown. The early maturing fibres of the vascular bundles reveal a maximum absorbance value at 280 nm (guaiacyl peak) whereas the late maturing fibres display a shoulder at 310-320 nm in young culms and a guaiacyl peak in older culms. The S(2) fibre wall has a lamellar structure with an increasing lignin content from the centre towards the compound middle lamella. The compound middle lamellae show higher absorbance values and are richer in p-coumaric and ferulic acid esters in comparison to the S(2) wall layers. The vessel walls have a low lignin content.