TOXIC EFFECTS OF HEAVY METALS ON PLANT GROWTH AND METAL ACCUMULATION IN MAIZE (ZEA MAYS L.)

Background: A pot experiment was conducted to determine the toxic effects of some heavy metals on the plant growth and seed yield of maize (Zea mays L.). Materials and Metheds: Heavy metals Mn, Pb, Cd, Cr and Co individually and in combinations were added as chloride salts in solutions to the pots before sowing. The test plants for were harvested after 80 days of germination and evaluated for nitrogen, protein and heavy matal content was determined. Resalts: Heavy metals caused significant decreases in growth and protein content. Cd was the most toxic metal followed by Co, Hg, Mn, Pb, and Cr. Protein content decreased from 16.0–68.4% in metal exposed plants at metal concentrations equivalent to those found in Conclusion: Metal accumulation by seeds was directly related to the applied heavy metal with greater concentrations of metals found in cases where metals were added individually rather than in combinations. The toxic effects on the plant growth, nitrogen content in different plant parts, and protein content in seeds, exerted by two metals in combination were only as harsh as for the most toxic metal individually probably due to their antagonistic effects.