Variation of Microfibril Angle Between Four Provenances of Sitka Spruce (Picea sitchensis [Bong.] Carr.)

: The mean microfibril angle (MFA) of tracheids in Sitka spruce (Picea sitchensis [Bong.] Carr.) from four provenances was determined by X-ray diffraction. Seeds were from four locations in North America: California, Oregon, Queen Charlotte Islands and Washington. Transplants were planted in 1976 and grown in Ireland (Shillelagh Forest). The mean MFA close to the pith was ca. 22° and decreased to ca. 11° in the outer rings. It was found that the MFA varies strongly not only as a function of the annual ring and the distance from pith but also as a function of the seed origin. Trees of California and Queen Charlotte Islands provenance had a larger mean MFA in general than trees of Washington and Oregon provenance. Also, the shapes of the cell cross sections were determined to some extent from the diffraction patterns. For samples of California and Washington provenance the average thickness of the cellulose crystallites was determined to be about 3.0 nm.