Resumo

COLMENARES-TREJOS, Sara L.; MELGAREJO, Luz Marina  e  ROMERO A., Hernán Mauricio. Ecophysiological studies of two andean forest contrasting species Abatia parviflora and Myrcianthes leucoxyla under Bogotá conditions, Colombia. Braz. J. Plant Physiol. [online]. 2011, vol.23, n.4, pp. 305-312. ISSN 1677-0420.  http://dx.doi.org/10.1590/S1677-04202011000400008.

The physiological response of high Andean forest contrasting plants, Myrcianthes leucoxyla, a shadow-facultative heliophyte, and Abatia parviflora, a heliophyte, was studied during the transition from dry season to wet season in Bogotá. Light response curves (A-PAR), water potential (Ψw), transpiration rate (E), stomatal conductance (gs), leaf soluble protein content and peroxidase activity were measured in this study in a 48h cycle. The values for E, gs, Ψ_w and Ψ_{w predawn} for M. leucoxyla were 0.07 to 4.89 µg/cm s, 0.02 to 0.5 cm s^-1, -0.025 to -1.05 MPa, and-0.1 MPa, respectively. For A. parviflora E, gs, Ψ_w and Ψ_{w predawn} were 0.47 to 12.27 µg/cm s, 0.17 to 1.42 cm s^-1, -0.05 to -0.3 MPa and -0.075 MPa, respectively. A. parviflora presented a tendency of stomatal closure at midday and peroxidase activity increased with the increasing solar radiation, this did not occur in M. leucoxyla. The light compensation point (I_c) in A. parviflora was about 18.10 µmol photon m^-2s^-1, typical for a heliophyte plant; while for M. leucoxyla it was 8.87 µmol photon m^-2s^-1, slightly above the maximal reported values for shadow plants and under the minimal reported values for light plants. The lowest photosynthetic rate (A) of M. leucoxyla (2.8 µmol CO₂ m^-2s^-1) in comparison with A. parviflora (7.4 µmol CO₂ m^-2s^-1) is compensated with a better photonic use efficiency (± 0.7792 mol C mol^-1).

Palavras-chave : A-PAR curves; Gas exchange; Heliophyte; Shadow plant; Water potential.