Resumo

PAVLOTZKY-BLANK, Benjamín  e  MURILLO-GAMBOA, Olman. Expected  genetic gain in Acacia mangium in  Los Chiles, northern  of  Costa  Rica. Agron. Mesoam [online]. 2012, vol.23, n.1, pp.93-106. ISSN 2215-3608.

 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, number of  commercial  logs per tree, forking, forking height  and log  quality  of  the  first four  logs  were  evaluated.  Wood commercial volume per tree and hectare was estimated. Data was analyzed with  SELEGEN software from EMBRAPA in 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 the two 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 22.9 m3/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, therefore, there is a potential usage of this trait in early selection thus,  shortening future selections.

Palavras-chave : Tree improvement; provenances; progeny test; genetic correlation.

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