Generation mechanism of growth stresses in wood cell walls: Roles of lignin deposition and cellulose microfibril during cell wall maturation

To explain the generation mechanism of tree growth stresses in relation to time and location inhomogeneity in the secondary wall lignification, we made a theoretical discussion by using an analytical model. In this analysis, time dependence, which has not been explicitly considered in a conventional model, was introduced. This made us possible to simulate the generation process of the growth stresses as a time dependent phenomenon attendant upon the secondary wall maturation. Analysis well explained the experimental results quantitatively on the assumption that a tensile stress originates in the cellulose microfibril as a bundle and a compressive stress are generated in the matrix skeleton during the secondary wall lignification. This verifies the propriety of "the unified hypothesis" proposed by Okuyama et al. quantitatively.