Generation process of growth stresses in cell walls: Relation between longitudinal released strain and chemical composition

Summary To advance the discussion on the evolution mechanism of tree growth stresses, the relation between released strain and the chemical components was investigated experimentally. The expansive released strain in the longitudinal direction assumed large values as the lignin content increased in the compression wood, but there was no relation between released strain and lignin content in the normal wood region. The contractive released strain assumed large values as the cellulose content and its crystallinity increased. Their correlation was very high and clear. From these facts, it is considered that the lignin deposition plays an important role in the generation of the growth stresses in compression wood but is not important in normal or tension wood regions. Cellulose microfibrils contract along their longitudinal axis during cell maturation, and the stress included by the contraction creates a longitudinal growth stress in normal and tension woods.The authors thank Prof. R. R. Archer, University of Massachusetts, for his valuable advice. A part of this research was supported by a grant under the Monbusho International Scientific Research Program