In the present work, effectiveness of chlorophyll a fluorescence as quick tool to detect effect Pb–stress on Limbarda crithmoides and Helianthus annuus species, when exposed increasing Pb concentrations (0–500 µmol.L–1) for 45 days, was evaluated. The level in plant leaves, well fresh weight content shoots roots both were also determined. L. did not show any significant variation photochemical ...