GENETIC CONTROL AND GENOTYPE-BY-ENVIRONMENT INTERACTION OF WOOD WEIGHT IN Eucalyptus CLONES IN THE STATE OF RIO GRANDE DO SUL, BRAZIL

ABSTRACT The present study aimed to evaluate the genetic control and genotype-by-environment interaction in wood weight of Eucalyptus clones in four environments located in the state of Rio Grande do Sul, Brazil, aiming to select superior genotypes. In 2007, a network of clonal tests was established with 864 clones of Eucalyptus. At three years of age, diameter at breast height and total height were measured, as was depth of Pilodyn penetration, for indirect inference of wood basic density. The mean annual increment of dry weight (MAIweight) was calculated. Individual heritability of 0.148 and of 0.48 was found for MAIweight and Pilodyn penetration depth, respectively. The genetic correlation between environments ranged from 0.503 to 0.926 for all traits. The genotype-by-environment interaction was significant for the MAIweight index (0.533). From the environment interaction analysis, 3 "improvement areas" were defined for the trait MAIweight. The grouping of the traits wood density and volume to create a wood weight index was essential for a more accurate selection, since there was a change of 37% compared to the ranking of clones for volume. The simultaneous selection for stability and adaptability provided higher gains when compared to selection based on predicted genotypic values between environments. Moreover, MHPRVG allowed an increase in gains compared to the control. Thus, the five best clones were selected based on these criteria: 39912 (E. urophylla), 39659 (E. urophylla), 6808 (E. grandis), 36190 (E. saligna), 39407 (E. grandis x E. urophylla)