Photosynthetic Behavior of Gmelina Arborea Roxb. Genotypes at 15-months-old Plantation, South Pacific of Costa Rica
Carlos Ávila Arias, Olman Murillo Gamboa, Dagoberto Arias Aguilar, Guerald Eduardo Flores Hurtado, Rafael Murillo Cruz, William Hernández Castro

Abstract
The aim of this investigation was to determine the photosynthetic capacity of five genotypes at 15-months-old plantation of Gmelina arborea. A clonal trial was conducted, taking one individual (ramet) at random from each of five clones at each of five blocks, for a total of 25 trees assessed. The study focused on clonal response to the light curve, and their performance in terms of gas exchange. No statistically significant differences were recorded between genotypes investigated for any of the parameters obtained from the light response curves. At the species level, maximum photosynthetic rate at light saturation (A_nmax) averaged 25.23 mol μmol CO₂ m^-2s^-12 m^-2s^-1.Clone 5 showed the highest values for A_nmax and LSP (19% and 41% above the overall average respectively), becoming the most effective in terms of photosynthetic capacity from the five clones evaluated in the field. No statistically significant differences between clones for any of the gas exchange parameters obtained were detected.

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