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 This research was supported by USDA-ARS=USAID and IITA. *Correspondence: Sylvester O. Oikeh, International Institute of Tropical Agriculture (IITA), PMB 5320, Ibadan, Nigeria; Fax: (2342) 2412221; E-mail: [email protected]. JOURNAL OF PLANT NUTRITION Vol. 26, Nos. 10 & 11, pp. 2307–2319, 2003 DOI: 10.1081=PLN-120024283 0190-4167 (Print); 1532-4087 (Online) Copyright # 2003 by Marcel Dekker, Inc. www.dekker.com 2307 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 , while kernel-Zn levels ranged from 16.5 to 24.6 mg kg . Environment did not have a significant effect on kerneliron and -zinc levels, but genotype by environment (G 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 (R1⁄4 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.