Variation in tracheid length in blue pine (Pinus wallichiana A. B. Jackson)

Abstract

Radial pattern of variation in the first-formed earlywood tracheid length in blue pine shows that it increases outwards from the pith at first rapidly up to the 10th ring, then more slowly up to about the 40th ring and thereafter it remains more or less constant. It is correlated significantly and positively with both age and distance from the pith up to 40 years. In the mature wood zone i.e. after 40 years, tracheid length is not affected by either age or distance from the pith. The mean tracheid length of mature wood is significantly and positively correlated with the mean tracheid length of juvenile wood and also with the tracheid length of each of the juvenile wood rings. Based on the results of this study some guidelines for sampling are proposed. Trees with greater than 51 cm d.b.h. or above 40 years of age can be compared by sampling only four outermost consecutive mature wood annual rings; and those with less than 51 cm d.b.h. or below 40 years of age can be compared by sampling any of the juvenile wood rings.