Genotypic differences in concentration and bioavailability of kernel-iron in tropical maize varieties grown under field conditions

Iron deficiency is estimated to affect over one-half the world population. Improving the nutritional quality of staple food crops through breeding for high bioavailable iron represents a sustainable and cost effective approach to alleviating iron malnutrition. Forty-nine late maturing tropical elite maize varieties were grown in a lattice design with two replications in three locations representing three agroecologies in West and Central Africa to identify varieties with high levels of kernel-Fe. Bioavailable iron was assessed for some varieties selected for high Fe concentration in kernel and improved agronomic traits using an in vitro digestion/Caco-2 cell model. Significant differences in kernel-Fe and -zinc concentration were observed among varieties (P < 0.001). Kernel-Fe levels ranged from 16.8 to 24.4 mg kg(-1), while kernel-Zn levels ranged from 16.5 to 24.6 mg kg(-1). Environment did not have a significant effect on kernel-iron and -zinc levels, but genotype by environment (G x E) interaction was highly significant. The genetic component accounted for 12% of the total variation in kernel-Fe and 29% for kernel-Zn levels. Kernel-Fe was positively correlated with kernel-Zn (R = 0.51, P < 0.0001). Significant differences in iron bioavailability were detected among selected Fe-rich varieties grown at one location. Mean bioavailable Fe ranged between 30% below to 88% above the reference control variety. The results indicate that genetic differences exist in kernel-Fe and -Zn concentrations and Fe bioavailability These differences may be useful in biofortification intervention programs, but additional research is needed to determine the efficacy of iron-rich Maize varieties in alleviating iron deficiency in humans.