Resumo

PAVLOTZKY, Benjamín  e  MURILLO, Olman. Expected genetic gain and genotype-environment interaction in Acacia mangium in the northern region of Costa Rica. Agron. Costarricense [online]. 2014, vol.38, n.2, pp.08-17. ISSN 0377-9424.

Two Acacia mangium Willd. progeny tests were evaluated, pursuing an increment in the profitability of commercial plantations. The 25 open-pollinated families were established in Los Chiles and San Carlos, northern region of Costa Rica, in year 2006, and evaluated in 2007 and in 2010. Genetic material came from plus tree selections obtained by GENFORES, a costarican tree-improvement and gene-conservation cooperative. In each trial, families were represented by 48 progenies, planted in 4 pairs randomly distributed within each of the 6 blocks. In 2010, DBH, survival rate, commercial number of logs per tree, forking, forking height and log quality in the first 4 logs, were evaluated. Based on these measurements, wood commercial volume per tree and per hectare were estimated. Data was analyzed with SELEGEN software from EMBRAPA, Brasil, in order to determine all genetic parameters of the breeding population. All traits evaluated showed family mean heritability values over 0.46. Genetic gain in commercial volume per hectare was estimated as 55.8%, when selecting as parents the 2 best individuals from the top 12 families, which would correspond to an expected commercial volume.ha^-1, at 4 years age, of 78.93 m³.ha^-1 (around 20 m³.ha^-1.year^-1). The 2 Colombian provenances were significantly superior in growth to the rest of the evaluated materials. No significant gene-environment interaction was observed between both sites. Genetic correlations among evaluated traits showed that diameter growth rate is expressed early in this tree species, thus could be used in shortening future selections.

Palavras-chave : Tree improvement; provenances; progeny test; genotype-environment interaction; genetic correlation; Acacia mangium; Costa Rica.

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