Wood physical properties, color, decay resistance and stiffness in Tectona grandis clones with evidence of genetic control

Tectona grandis (teak) plantations are being produced with trees from genetic improvement programs, including clonal selection. However, limited information about inheritance of wood properties is available. For studying genetic parameters of T. grandis wood properties and stem diameter two 10-yr-old trials were studied involving nominally 2 sites × 20 clones × 3 replicates × 1 ramet. Clonal variation was observed in: heartwood (HWP), pith (PP) and bark (BP) percentages; green moisture content (IMC) and density (GD); tangential (TS), radial (RS) and volumetric (VS) shrinkage and ratio tangential/radial: shrinkage (ratio T/R); L*a*b* color parameters; and stiffness and specify gravity (SG). Some wood properties evidenced strong across-sites genotypic control. The higher broad-sense heritability estimates (over 0.36) were for PP, IMC, SG, TS, VS and L*, a*, and b* color coordinates and stiffness. Low and non-significant values were estimated for HWP, BP, GD, RS, ratio T/R and decay resistance of sapwood and heartwood to Trametes versicolor and Pycnoporus sanguineus. However, HWP showed marked clone x site interaction. Phenotypic and tentatively estimated genotypic correlations indicate that selecting faster-growing clones will improve some important wood properties, such as increasing HWP, and decreasing PP and BP, without affecting other wood properties. Selecting clones for denser wood, as expected, improved stiffness, should decrease IMC and affect negatively b* (yellow/blue) color. Clone selection with lower L* values could increase redness (a*) of wood.