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

Author(s)

Monteiro‚ J.A.F. ; Prado‚ C.H.B.A.

• Document type: Journal article
• Source: Photosynthetica; v. 44, n. 1, p. 39-45, 2006.

Abstract

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)

• FAPESP's process: 00/10910-4 - Photosynthesis response in relation to different concentrations of CO2 in two wooded species of Cerrado in the dry and rainy seasons
• Grantee: Jose Alberto Fernandez Monteiro
• Support Opportunities: Scholarships in Brazil - Scientific Initiation