A study was made of the role of various heavy metals (chromium, zinc, copper and cadmium) together with the effects of NaCl-salinity, PEG-mediated water stress and temperature on growth and superoxide dismutase (SOD) activity in hydrilla (Hydrilla verticillata L.). Almost all metals studied reduced growth but presented a modulatory effect at lower concentrations. NaCl-salinity, water stress and temperature treatments also reduced growth. SOD activity was inhibited by both chromium and zinc but increased by copper and cadmium. NaCl-salinity increased SOD activity while water stress decreased it. SOD showed thermostability with a higher activity being recorded at 45ºC.
growth; heavy metals; NaCl; PEG; superoxide dismutase; temperature
