Lignification and cell wall thickening of ray parenchyma cells in Scots pine sapwood

What is it about?

Scots pine is a European softwood species widly used in different fields of applications. The species shows variations in ray anatomy, which are only poorly understood. We conducted a microscopic study at two different radial positions on a stem disc on a selection of trees from different stands with the theory that some ray parenchyma cells develop thick and lignified cell walls early in the sapwood. This study reveals differences in ray anatomy, especially the commonness of thick-walled and lignified ray parenchyma cells in the outer and inner sapwood of Scots pine sapwood. A considerable variation in the presence of thick-walled and lignified ray parenchyma cells in the outer sapwood is shown in this study, where thickened and lignified cell walls are common in ray parenchyma of some trees. Lignification and cell wall thickening are more common in the inner sapwood, but for some trees, the difference is small due to the already high rate of lignification and cell wall thickening in the outer sapwood. Different patterns of lignification and cell wall thickening can cause variations in the performance of the material in practice and are particularly relevant for impregnation treatments with protection agents. The anatomical differences discovered in this study contribute to a better understanding of the variation in wood properties of Scots pine. The knowledge from this study can be used to advance purpose-adjusted material selection.

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