Publicação on-line; 27 ref.; 3 illus.; Summary (En)

Abstract

In this study, we assessed the gas exchange in Caryocar brasiliense seedlings in water deficit conditions and their
capacity to recover after rehydration. We assessed plant photosynthetic rates, internal carbon concentrations, stomatal
conductance, transpiration rates, water-use efficiency, instantaneous carboxylation efficiency, chlorophyll index, and
photosystem II quantum efficiency. All gas exchange parameters were reduced after the suspension of irrigation.
Seedling photosynthetic rates approached zero after 12 days. The equilibrium was reestablished in all variables 11 days
after re-initiating irrigation, with the exception of internal CO2 concentration and stomatal conductance. Exposure
of seedlings to water stress resulted in drastically reduced photosynthetic processes. This reduction occurred due
to the limitation of stomatal conductance and low rubisco carboxylation efficiency but not to irreversible damage
photosystem II. All of these parameters demonstrated recuperation with rehydration, but only the photosynthetic
rates reached initial control values.

Keywords: hydric stress, native fruit, Pequi, Caryocaceae