Seleção precoce para incremento simultâneo do crescimento e da qualidade da madeira em Pinus taeda L.

Abstract

The objective of this work was to study the efficiency of the early selection of parents and progeny for simultaneous increment of the growth and wood quality. For this, 48 open-pollinated families of Pinus taeda were grown at close spacing (0,5m x 0,5m). At the age of 16 months they were assessed for stem diameter at 30 cm above the ground and for wood basic density. The data were compared to diameter at breast height and basic density of commercial stem of the same progenies at 84 months under field conditions. Phenotypic and genetic parameters were estimated using an individual tree model. The narrow sense heritabilities in the 16º and 84º month for diameter (h² = 0,24 e 0,22) and density (h² = 0,27 e 0,19) suggest that they are inherited. The aditive genetic age-age correlations were highly for diameter (r² = 0,90) and for basic density (r² = 0,86) indicating that growth and basic density at maturity could be improved by early selection of the same growth and quality trait. Trait-trait correlations indicated that genetic correlations between diameter and wood basic density were negative and high indicating difficulties for simultaneous genetic gain by selection. Efficiencies of early selection indicated similar efficiency for the same trait at 84 months. To improve volume and quality of wood nine parents were selected by aditive genetic breeding values at the two ages. This allows to conclude that early evaluation of progeny grown in close-spacing in a nursery field is a useful methodology to increase genetic gains in an generation by increasing the probability of selecting genotypes that favor simultaneously wood quality and growth traits.