Buffering of copper and cadmium toxicity for lucerne plants, by means of using compost addition
1993
Gonzalez M, Sergio (Instituto de Investigaciones Agropecuarias, Santiago (Chile). Estacion Experimental La Platina)
Two post-experiments, using lucerne plants (Medicago sativa cv. Espanola) as indicators, were conducted to determine absolute maximum Cu and Cd upper critical levels and changes in presence of compost, at La Platina Experimental Station under uncontrolled greenhouse conditions. Though sensitive to accumulation of both metals in the root growth medium, plants were significantly more affected by Cd when the growth medium was pure sand; thus, the absolutes UCL were 4 and 23.5 mg/kg, for Cd and Cu, respectively. The addition of compost to the root growth medium clearly buffered the phytotoxicity of both metals, showing Cd the highest reduction rate. For this metal, the UCL was increased around 23 times (92.7 mg/kg) whereas the Cu-UCL was increased 9.5 times (225.2 mg/kg). Chemical analysis of harvested tissues revealed that Cu content did not significantly changed, when Cu content in the growth medium increased up to the UCL; this fact was observed either in pure sand and in sand/compost mixture, reflecting no biomagnification of Cu by lucerne plants. Conversely, under the same conditions, Cd content in green tissues increased several time compared with blank treatments, reflecting high biomagnification of Cd by lucerne plants
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