Genetic variation of growth traits and wood characteristics among landraces of Gmelina arborea Roxb. in the upper Magdalena, Colombia

The selection of superior genetic material based on the genetic values of traits of economic interest is of importance in the forest industry to maximize the productive potential of planted forests. Gmelina arborea has adapted to the environmental conditions of the American tropics, giving rise to promising landraces for commercial reforestation programs to produce sawn timber. Our objective here was to evaluate through genetic parameters the development and adaptation of 16 landraces of G. arborea in a nine-year provenance trial in tropical dry forest conditions in upper Magdalena, Colombia. The trial evaluated the survival, the growth traits (diameter, total height, and volume), and the wood characteristics (green and basic density and dynamic elasticity modulus). Broad-sense heritability, genetic gains, and genetic correlations were estimated for the growth traits and wood characteristics. The traits with the highest mean heritability were the individual (H-p(2) = 0.1158) and cumulative volumes (H-p(2) = 0.1095). Genetic gains in the cumulative volume of the best two landraces compared with the mean of the control lot (landrace 14) would amount to 3.8 % for landrace 10 and 3.5 % for landrace 11, both from the Department of Atlantico. Negative genetic correlations were found between the basic wood density and the growth traits, especially in the diameter (r(g) = -0.694) and the individual tree volume (r(g) = -0.637). The landraces with superior productivity identified in the study would increase the genetic base and allow the establishment of new high-yield plantations in the region.