Inheritance pattern and genetic correlations among growth and wood quality traits in Para rubber tree (Hevea brasiliensis) and implications for breeding

Inheritance pattern of wood traits viz. specific gravity, fibre dimensions and fibre-derived biometrical indices and their interactions among themselves and with that of growth are reported in Hevea brasiliensis. Girth (h2 = − 0.02 ± 0.44 to h2 = 0.35 ± 0.24) showed moderate genetic control. Among wood traits, specific gravity (h2 = 0.15 ± 0.31 to h2 = 0.33 ± 0.28) was found to be under moderate genetic control. Fibre traits viz., fibre length (h2 = − 0.26 ± 0.30 to h2 = 0.50 ± 0.34), fibre diameter (h2 = 0.19 ± 0.49 to h2 = 0.70 ± 0.11), fibre lumen diameter (h2 = − 0.18 ± 0.35 to h2 = 0.56 ± 0.47) and fibre wall thickness (h2 = − 5.17 ± 5.26 to h2 = 0.50 ± 0.50) were under moderate to strong genetic control. Among fibre-derived indices, flexibility coefficient (h2 = 0.48 ± 0.21 to h2 = 0.89 ± 0.29) showed moderate to very strong genetic control. The Runkel ratio (h2 = − 0.40 ± 0.27 to h2 = 0.42 ± 0.29) and slenderness ratio (h2 = − 0.36 ± 0.29 to h2 = 0.43 ± 0.28) showed moderate genetic control. Girth showed very strong positive genetic correlation with fibre wall thickness and strong positive correlation with fibre width indicating scope of indirect selection potential for these traits. Wood specific gravity was not correlated with either girth or fibre traits. Hence, it would be possible to concomitantly improve growth and fibre traits without adversely affecting wood specific gravity. Moderate to very high estimates of heritability for fibre traits, girth and specific gravity indicated that considerable genetic gain can be realised for these traits. Implications of the above findings in genetic improvement of wood in Hevea are discussed.