Effects of lead and chelators on growth, photosynthetic activity and Pb uptake in Sesbania drummondii grown in soil

Effects of lead (Pb) and chelators, such as EDTA, HEDTA, DTPA, NTA and citric acid, were studied to evaluate the growth potential of Sesbania drummondii in soils contaminated with high concentrations of Pb. S. drummondii seedlings were grown in soil containing 7.5 g Pb(NO3)2 and 0–10 mmol chelators/kg soil for a period of 2 and 4 weeks and assessed for growth profile (length of root and shoot), chlorophyll a fluorescence kinetics (Fv/Fm and Fv/Fo) and Pb accumulations in root and shoot. Growth of plants in the presence of Pb + chelators was significantly higher (P < 0.05) than the controls grown in the presence of Pb alone. Fv/Fm and Fv/Fo values of treated seedlings remained unaffected, indicating normal photosynthetic efficiency and strength of plants in the presence of chelators. On application of chelators, while root uptake of Pb increased four-five folds, shoot accumulations increased up to 40-folds as compared to controls (Pb only) depending on the type of chelator used. Shoot accumulations of Pb varied from 0.1 to 0.42% (dry weight) depending on the concentration of chelators used.