EVALUATION OF GENETIC PARAMETERS FOR GROWTH TRAITS AND WOOD PROPERTIES IN CLONES OF Hevea brasiliensis (Willd. Ex Adr. Juss.)

Abstract

Hevea brasiliensis is a forest species with potential for commercial planting for both latex and timber production at the end of the latex production cycle. This study aimed to determine the genetic variability of growth traits and wood properties in a 33-year-old clonal plantation of H. brasiliensis in the region of Selvíria, state of Mato Grosso do Sul. Significant differences were detected among the clones for DBH and total tree height. For the physical properties of the wood, only volumetric shrinkage showed a significant difference between clones; however, for all anatomical dimensions and mechanical properties, significant differences were found. Clone IAN717 stood out for the highest growth, while RRIM600 had the lowest growth. In terms of wood properties, clone RRIM600 exhibited highest mechanical resistance, while GT1 showed the lowest resistance. Most wood properties varied in the pith-to-bark direction, with the lowest values found in the pith region and the highest in the bark region, except for vessel frequency, where the opposite trend occurred. The highest heritability coefficients were observed for DBH, volumetric shrinkage in the bark region, vessel element diameter in the intermediate region, and vessel frequency in the bark region. The genetic correlation coefficient was high, positive, and significant between traits such as shear strength x modulus of rupture, modulus of elasticity x modulus of rupture, and volumetric shrinkage x modulus of rupture, indicating that selection for one trait may result in indirect gains in another.

Keywords

• Clonal test
• Rubber tree
• Genetic improvement
• Wood quality