Comparative stomatal conductance and chlorophyll a fluorescence in leaves vs. fruits of the cerrado legume tree, Dalbergia miscolobium

Abstract

The aim of this study was to compare water vapor conductance and chlorophyll a fluorescence between leaflets and fruits of Dalbergia miscolobium, the Jacaranda tree. The frequency of stomata on the leaflets was 20 times higher than that observed on the fruits, and this was related with the lower conductance of the fruits in comparison with the leaflets. The potential quantum yield of PSII (Fv/Fmax was significantly lower in fruits than in leaflets. The Fv/Fmax values for leaflets increased to over 0.8 during the afternoon, indicating the occurrence of dynamic photoinhibition. In contrast, Fv/Fmax values for fruits remained low even at early morning, indicating the occurrence of chronic photoinhibition. The maximum values of effective quantum yield (ΔF/F 'm), and of the apparent electron transport rate (ETRmax) were higher in leaflets than in fruits. It was concluded that, like other green tissues, the pericarp of D. miscolobium was photosynthetically active, and therefore can contribute to the maintenance of the fruits and/or to the development of the seeds.