Phenotypic assessment of wood density and stiffness in Melia dubia plantations from three locations using non-destructive tools

Abstract

Phenotyping large populations for assessing the variability for wood traits is the basic and critical step for developing improved genotypes/clones in the conventional or molecular marker-based tree improvement programmes of timber-yielding species. Melia dubia is rapidly emerging as a potential timber species with large-scale plantations being raised in different parts of India. In this study, large number of M. dubia trees (n = 940) were phenotyped for girth at breast height, wood basic density and stiffness from six plantations at three different locations, i.e. Yeshwanthpura (Kolar district), Hunsur and adjoining areas (Mysore district) and Kollegal (Mandya district) of Karnataka. Non-destructive tools namely pilodyn penetrometer and stress wave timers were used for phenotyping of wood density and wood stiffness, respectively. Across the locations, pilodyn penetration ranged from 12 to 30 mm and stress wave velocity ranged from 3.45 to 4.54 km/s. Plantations in the Hunsur area were characterized with relatively high pilodyn penetration (means low basic density), whereas stress wave velocity was uniformly distributed in all three locations. 11.68% of total number of trees (3.11% with GBH ≥ 37.5 cm from Yeshwanthpura and 8.57% trees from Kollegal) exhibiting pilodyn penetration range from 12 to 17 mm can be considered for selection for high density and 19.3% of trees (3.9% of trees from Yeshwanthpura, 4.4% trees from Hunsur and 11.02% trees from Kollegal) having stress wave velocity ranging from 4.05 to 4.46 km/s can be considered for high stiffness in the future tree improvement programmes. More than twofolds variation in pilodyn penetration and sufficiently large variation in stress wave velocity provide the opportunity for the development of trait-specific markers.