An analysis of biomonitoring quantum efficiency Aspidosperma pyrifolium (Mart.) and Poincianella pyramidalis (Tul.) L. P. Queiroz, was measured between 2012 and 2013 in order to understand possible strategies of survival for species under extreme drought conditions in Soledade City, semiarid region of ParaÃba. Three leafs of the middle portion of randomly arranged in three individuals and populations exposed to intense light, a total of nine replicates per population were chosen. The values of quantum efficiency in P. pyramidalis recorded an increase in July (0.652), August (0.785) and September (0.667) of 2012, in response to increased local precipitation occurred in June of 2012. Similar response was observed in the A. pyrifolium which showed mean values of 0.745 in August and 0.685 in September of the same year. P. pyramidalis showed greater resistance to water stress, with values of quantum efficiency (0.712), in December of 2012, compared to A. pyrifolium (0.353). The plant species exhibit a seasonal response to water deficit experienced to the study period.
