MSc

In the state of Kerala, heartwoods of lesser known timber species viz., Albizia odoratissima (Ceylon rosewood) and Samanea saman (rain tree) are allegedly being used as “substitutes” and “adulterants” for making furniture of Dalbergia. latifolia (Indian rosewood) mainly due to their similar wood colour. As this spurious practice has serious implication in timber trade, a study was undertaken to profile the selected wood properties of all these three species to highlight their similarities and differences. The study involved analyzing selected physical, mechanical, anatomical and biochemical properties of A. odoratissima and S. saman and comparing it with the wood properties of D. latifolia as available from relevant literatures.

Variations of higher magnitude were noted between the three species for some wood properties, and with respect to few other properties, the differences were lesser. Significant variations were also observed between tissue types viz., sapwood and heartwood for some wood properties.

Heartwood tissue types of S. saman and D. latifolia displayed high calorific value, where as, for A. odoratissima both tissue types (sapwood and heartwood) exhibited medium calorific value. The physical properties of the heartwood of A. odoratissima were observed to be higher than that of D. latifolia. S. saman possessed lower values for the physical properties as compared to D. latifolia. Basic specific gravity, radial and volumetric shrinkages (green to oven dry) were considerably different for all the three species. Generally, for both Ceylon rosewood and rain tree tangential shrinkage was higher than radial shrinkage for both the tissue types.

Mechanical properties of A. odoratissima were superior to D. latifolia and S. saman, except modulus of elasticity in compression parallel to grain. On the other hand mechanical properties of S. saman were closer to D. latifolia. Measure of fibre stress at limit of proportionality and modulus of elasticity in static bending and modulus of elasticity in compression parallel to grain are considerably different for the three species. In A. odoratissima and S. saman, the mechanical properties of sapwoods varied non significantly with the strength properties of heartwoods. S. saman exhibited superior strength properties for heartwood over its sapwood.

Vessel diameter, distribution of parenchyma and ray height can be used to differentiate the three species. In all the species, along the radial axis from pith towards periphery, the vessel diameter, ray height, ray width increased along the region of heart wood. Likewise, ray frequency, and vessel frequency decreased along radial axis in heartwood region. Average vessel diameter, ray height and ray width of sapwoods were greater than that of the heartwoods.

Lignin, cellulose and holocellulose percent of A. odoratissima and S. saman were significantly greater than D. latifolia. Higher lignin, cellulose and holocellulose content are responsible for the higher strength properties of A. odoratissima. Methanol-acetone extracts of heartwood of D. latifolia exhibits specific peak wavelengths under spectrometric analysis, which are not found in the other two species. Phenolic compounds were observed to influence some of the physical properties.