Apparent carboxylation efficiency and relative stomatal and mesophyll limitations of photosynthesis in an evergreen cerrado species during water stress

Autor(es)

Monteiro‚ J.A.F. ; Prado‚ C.H.B.A.

• Tipo de documento: Artigo Científico
• Fonte: Photosynthetica; v. 44, n. 1, p. 39-45, 2006.

Resumo

Miconia albicans, a common evergreen cerrado species, was studied under field conditions. Leaf gas exchange and pre-dawn wleaf water potential (Psi(pd)) were determined during wet and dry seasons. The potential photosynthetic capacity (P-Npmax) and the apparent carboxylation efficiency (epsilon) dropped in the dry season to 28.0 and 0.7%, respectively, of the maximum values in the wet season. The relative mesophyll (L-m) and stomatal (L-s) limitations of photosynthesis increased, respectively, from 24 and 44% in the wet season to 79 and 57% at the peak of the dry season when mean Psi(pd) reached -5.2 MPa. After first rains, the P-Npmax, epsilon, and L-m recovered reaching the wet season values, but L-s was maintained high (63%). The shallow root system growing on stonemason limited by lateral concrete wall to a depth of 0.33 m explained why extreme Psi(pd) was brought about. Thus M. albicans is able to overcome quickly the strains imposed by severe water stress. (AU)

• Processo FAPESP: 00/10910-4 - Resposta da fotossíntese em função de diferentes concentrações de CO2 em duas espécies lenhosas de Cerrado nas estações seca e chuvosa
• Beneficiário: Jose Alberto Fernandez Monteiro
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica