Expected genetic gain in Acacia mangium in Los Chiles, northern of Costa Rica. An Acacia mangium Willd. progeny test conformed by 25 families was evaluated with the objective of selecting the best materials in growth and stem quality. The trial was established in Los Chiles, Northern Costa Rica in 2006, and evaluated in 2007 and in 2010. Genetic materials came from breeding selections obtained by GENFORES, a tree improvement and gene conservation cooperative, in Costa Rica and Colombia. Each family was represented by 48 progenies, split in four pairs randomly distributed within each of the six blocks of the trial. DBH, DBH increment, survival rate, numberof commercial logs per tree, forking, forking height and log quality of the fi rst four logs were evaluated. Wood commercial volume per tree and hectare was estimated. Data was analyzed with SELEGEN software from EMBRAPAin order to obtain all genetic parameters for the breeding population. All traits showed family mean heritability values over 0.68. Genetic gain in commercial volume per hectare was estimated as 40.8%, when selecting as progenitors thetwo best individuals from the top twelve families at four year old, which corresponds to an expected commercial volume/ha at this age of 91.65 m3/ha, based on a growth rate of 22.9m3/ha/year. The two columbian provenances are significantly superior to the rest of the evaluated materials. Genetic correlations among traits show diameter growth rate early expressed in this tree species, there fore, there is a potential usage of this trait in early selection thus, shortening future selections.
Keywords: Tree improvement, provenances, progeny test, genetic correlation.