Gas exchange in young Hevea brasiliensis (Willd. Ex A. Juss.) Müll. Arg. (Euphorbiaceae) plants in Antioquia (Colombia

The aim of this study was to determine the behavior of Hevea brasiliensis from a study of photosynthetic performance in the environmental conditions of the rubber regions in northeast and lower Cauca of the department of Antioquia (Colombia) as a baseline for future studies of clonal performance between different environments. Photosynthetic parameters were recorded by an infrared gas analysis, and for each of the photosynthetic parameters was estimated the area under the curve (AUC) from 7 Hevea genotypes (clones). The maximum value of photosynthetic rates was reached at 8 hours in San Roque (10.97 µmol [CO2] m-2s-1) and 9 hours in Caucasia (7.84 µmol [CO2] m-2s-1). The maximum transpiration rates was 3.55 mmol [H2O] m-2s-1, in San Roque, and 5.16 mmol [H2O] m-2s-1 in Caucasia, while the maximum stomatal conductance was 0.18 mol [H2O] m-2s-1 y 0.16 mol [H2O] m-2s-1 in San Roque, and Caucasia respectively. The Caucasia-based rubber plants had higher cumulative net assimilation rates 271,934 µmol [CO2] m-2day-1, being higher than San Roque 226,287 µmol [CO2] m-2day-1. The mean carbon accumulation was obtained in San Roque (697,638 µmol [CO2] µmol photon-1day1). Hevea brasiliensis showed greater environmental adaptation with respect to gas exchange and the use of light energy in San Roque