Growth parameters and quantum efficiency measurements of the photosynthesis were evaluated on the emergent macrophyte Ludwigia decurrensunder different concentrations of nitrogen (0 mg/L, 465 mg/L y 930 mg/L). Growth was determined as measurements of total length and leaf area, and the emission of chlorophyll fluorescence was used as a measure of real quantum efficiency of the photosystem II. During the study period, a general tendency of increase of growth parameters and quantum efficiency with increase of nitrogen supply was noted. However, there was no significant difference (p<0.05) of emission of fluorescence among treatments. The results of the photosynthetic efficiency (Fv/Fm) behavior and the growth of the plant trated with different concentrations nitrogen, demonstrate that the macrophyte Ludwigia decurrenscan grow on enriched nitrogen environments.