Lipid peroxidation and activity of some antioxidative enzymes in the root of maize (<i>Zea mays</i>) cultivated on cadmium contamination soil

Abstract

In this study, we examined the tolerance capacity of Zea mays to cadmium pollution. Soil was treated with varied concentrations of Cadmium; 5 mg, 10 mg, 20 mg and 30 mg/kg soil and Zea mays planted. Root samples were collected in weeks 3, 4, 5 and 6. Activities of Peroxidase, catalase superoxide dismutase, and lipid peroxidation were investigated. Decrease in peroxidase activity was extremely significant (p <0.05) in weeks 4 and 5 while that of week 6 was not significantly (p > 0.05) different from normal. The decrease correlated with increase in Cadmium concentration. However, at the highest concentration of 30 mg/kg of soil the trend was not significant. Increase in the activity of catalase was recorded in weeks 3 and 6. This increase didn’t follow a particular trend but at higher  concentration of Cd and long term exposure, it became apparent. There was a negative correlation between catalase activity and lipid peroxidation. In week 3, catalase activity was not significant (p > 0.05) and lipid peroxidation was significant (p < 0.05) while at week 4, catalase activity was significant (p < 0.05) and lipid peroxidation was not significant (p = 0.8432). Catalase activity was not significant (p = 0.2753) at week 5 and lipid peroxidation was significant (p = 0.0030). At week 6 when catalase activity became extremely significant (p < 0.05), lipid peroxidation had a p value of 0.0128. Generally no significant activity (p > 0.05) was observed for superoxide dismutase. A significant increase in absorption of cadmium (p = 0.0374) at 30mg/kg soil was observed between weeks 5 and 6. It was also observed that cadmium had no significant effect (p > 0.05) on the root weight during the period of study. It’s suggestive therefore Cadmium
contamination of soil could affect growth of maize and induce oxidative stress.