FACTORS INFLUENCING TRACHEID LENGTH IN CONIFER STEMS

SUMMARY Because of the practical significance of tracheid length in the pulp and paper industry and of its correlation with properties, the variation of this feature within and between stems of certain species of Pinus has been investigated. The tracheid length has been related to the rate of radial growth of the stem and, in general within any one stem, it has been found that a wider growth ring has a low average tracheid length and a narrow growth ring a high average tracheid length. Some evidence was obtained of a similar correlation between stems. Trees with an initial high tracheid length maintained this characteristic through growth rings subsequently formed. Reasons for the variation in initial tracheid length are unknown, but in Pinus pinaster Sol. it appeared to have some relation to the “strain” of the species. Possible means by which stems of high initial tracheid length may be obtained are discussed.