Residual Accumulation of Chromium (Cr) and Copper (Cu) and their toxicities on Germination and Growth of three Maize (<i>Zea mays</i> L) varieties

Abstract

High levels of heavy metals in polluted soils are common, and concerns about their possible hazards to humans, livestock, and crops cannot be overemphasized. This study was carried out to determine the effects of Chromium (Cr) and Copper (Cu) on germination and seedling growth of Sammaz, Oba super and Oba 98 maize (Zea mays) cultivars in order to determine their potentials as susceptibility (bioindicators) or tolerance (bioremediators). Treatments of the heavy metal ranged 2.88, 5.76, 8.63, 11.51, and 23.02 mg kg^-1 for Cr, and 5000, 10000, and 15000 mg kg^-1 for Cu, and no chemical treatment (control). Heavy metals from the plants were determined by Atomic Absorption Spectrophotometry (AAS) machine. All chemicals used had different levels of their effects on germination percentage (%) in the following pattern of increasing order of magnitude Cr ˃Cu. Initial seedling growth and development were strongly impeded by Cu, except Cr in all the three maize cultivars with a little bit development in the root and shoot. The concentration of Cr in the shoot of the three maize cultivars is in the order of Oba 98 ˃Oba Super˃ Sammaz while that of the root is in the order of Oba 98˃Sammaz˃Oba super. It can be concluded that the toxicity of Cr and Cu at the concentrations used in this experiment showed susceptibility of all the three maize cultivars and the toxic effects of these heavy metals. Thus, the maize cultivars could be bio-indicators of Cr and Cu toxicity.