Grain Cadmium and Zinc Concentrations in Maize Influenced by Genotypic Variations and Zinc Fertilization

Zinc (Zn) fertilization could be a viable approach for minimizing cadmium (Cd) accumulation in the food chain. The present study was carried out to investigate the role of various Zn fertilization treatments (control, foliar application at tasseling stage, foliar application at milky stage, rubber ash application, soil application of ZnSO4) and cultivars (Pop 2004B, Pop 2006, Azam, Sarhad (W), Pahari) on grain yield, grain Zn, and grain Cd concentrations in maize. All Zn fertilization treatments resulted in a significantly higher grain yield, higher grain Zn concentration, and reduced grain Cd concentration. The application of rubber ash remained the best among all Zn fertilization treatments as it resulted in a higher grain yield of 62% and a reduced grain Cd concentration by 57% compared to control. Contradictions were apparent between cultivars, and the cultivars which recorded a higher grain yield had a lower Zn concentration in their grains and vice versa. Regarding Cd accumulation, all cultivars except Azam, retained less Cd with increased grain Zn concentration. Future studies should focus on breeding/selection of high yielding and high quality cultivars. Furthermore, the feasibility of rubber ash maybe tested under different climatic and edaphic conditions against other heavy metals and other crops as well.