Selección temprana en ensayos clonales de melina (Gmelina arborea Robx.) en Costa Rica

Introduction. The early selection age allows to accelerate genetic improvement programs and optimize forest production, in this case with melina (Gmelina arborea), which is the second most important forest species for commercial reforestation in Costa Rica. Objective. To determine the optimal selection age of melina in Costa Rica, by evaluating four genetic characters. Materials and methods. The study was carried out in Siquirres and Pérez Zeledón, the Caribbean region and the southern zone of Costa Rica, respectively. A randomized complete block design was used with four replicates (Sites 1 and 3) and six replicates (Site 2) per treatment. The initial spacing was 4 m x 3 m for the El Porvenir trial and 4 m x 4 m for the Siquirres and La Ceniza trials. Genetic parameters were calculated at different ages, for the variables diameter at breast height (DBH), commercial height, commercial volume, and shaft quality, with the SELEGEN software, which is based on the REML / BLUP method, in addition, genetic correlations were made between the evaluated variables. Results. The DBH and the commercial volume were the characters with the greatest genetic control, they presented the highest mean values of individual heritability and clonal mean, between 2.8 and 4 years of age. The highest genetic correlations (> 80%), between the DAP and commercial volume variables, occurred from 2.8 years of age, which increased in later ages until reaching values greater than 90 %. Conclusion. The range between 2.8 and 4 years could be determined as a possible age of genetic selection for melina.