Physiological responses of Zea mays seedlings to interactions between cadmium and salinity

The effects of 0, 2.5, 5.0, and 10.0 pmol/L Cd2+ (Cd(NO3)(2)center dot 4H(2)O) and 0, 10, 25, 50, and 100 mmol/L NaCl on growth, photosynthesis and the content of some ions in maize (Zea mays L.) were Investigated in the present study. With increasing concentrations of Cd2+ or NaCl alone in Hoagland nutrient solution, the chlorophylis and starch content decreased. Combination treatment with salinity and cadmium increased the negative effects observed following the two stresses alone. Plants exhibiting growth retardation in response to one mild stress factor (25-50 mmol/L NaCl) became more tolerant to the other stress factor (Cd). The exposure of plants to cadmium caused a partial reversal of the effects of salinity. Root and shoot growth, ion accumulation and levels of photosynthetic pigments were improved at moderate concentrations of the two stress factors imposed jointly.