EFFECT OF AGE ON VARIATION IN TRACHEID DIMENSIONS OF Pinus massoniana Lamb. PLANTED IN CAO BANG, VIETNAM

Abstract

Tracheids in softwood are similar to fibers in hardwood, which have the mechanical task of supporting the tree trunk, in addition to carrying out the task of transmitting water and nutrients to feed the tree. Therefore tracheid dimenssion is an important factor affecting the wood properties and varies with the age of the tree. This study aims to evaluate the effect of age on tracheid dimenssion of Pinus massoniana planted in Cao Bang. Research results showed: (1) Variation in tracheid dimenssion along the radius direction: In the earlywood, the values ​​of tracheid diameter, lumen diameter and cell wall thickness near the bark were always higher than those near the pith. However, statistical analysis showed that there was only a statistically significant difference (P < 0.05) in the value of tracheid dimenssion between two radial positions R1 and R2 at age 18 and age 24, while there was no statistically significant difference (P > 0.05) in the value of tracheid dimenssion between two positions R1 and R2 at age 12 although the average value at R2 was higher than at position R1. (2) Variation in tracheid with tree age: In both earlywood and latewood, cell wall thickness tended to increase as tree age increases. In this study, the highest cell wall thickness value was at age 24 (1.38 µm in earlywood and 2.90 µm in latewood) and the lowest was at age 12 (1.05 µm in learlywood and 2.20 µm in latewood). Cell wall thickness is the factor that most clearly affects the density of Pinus massoniana wood, explaining up to 66% of the variation in wood density value.