Photosynthesis, Transpiration, Stomatal Conductance, Chlorophyll Fluorescence and Chlorophyll Content in Brosimum alicastrum

Photosynthesis, stomatal conductance, transpiration, chlorophyll content and chlorophyll fluorescence were quantified in Brosimum alicastrum Swartz, developed in its natural habitat. Light curves show that maximum fixation of CO2 was 5 μmol m-2s-1, photosynthetic efficiency was 0.67 while the photosystem II was found to saturate at a photonic flux density (PFD) of 500 μmol m-2s-1, at 15 h. Since this species is shade tolerant, it initiates the photosynthetic process with low levels of light, presenting a light compensation point of 24 μmol m-2s-1. A high correlation was found between photosynthesis and transpiration. Highest water use efficiency occurred after at 15 hours at a temperature of 30°C, while chlorophyll levels remained constant throughout the whole diurnal cycle. The results obtained suggest that, during the daylight hours and at higher temperatures, this species can carry out photosynthesis with high water use efficiency. Based on the results, the conclusion is that this species is capable of adapting to a

diversity of environmental conditions.