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Agronomic biofortification of maize with selenium (Se) in Malawi

Chilimba, Allan D.C., Young, Scott D., Black, Colin R., Meacham, Mark C., Lammel, Joachim, Broadley, Martin R.
Field crops research 2012 v.125 pp. 118-128
application rate, biofortification, calcium ammonium nitrate, corn, crops, farms, fertilizers, food choices, selenium, soil, stover, whole grain foods, Malawi
Suboptimal dietary Se intake is widespread in Malawi due to low levels of plant-available Se in most soils and narrow food choices. The aim of this study was to determine the potential for biofortifying maize using Se-enriched fertilisers in Malawi. The response of maize to three forms of selenate-Se fertiliser was determined. Crops were treated with a liquid drench of Na₂SeO₄₍ₐq₎ (0–100gSeha⁻¹), a compound NPK+Se fertiliser (0–6gSeha⁻¹), or Se-enriched calcium ammonium nitrate (CAN+Se; 0–20gSeha⁻¹). Experiments with Na₂SeO₄₍ₐq₎ and NPK+Se were conducted at six field sites, and at a subset of three sites with CAN+Se, in 2008/09 and 2009/10 (i.e. 30 experimental units). The increase in grain Se concentration was approximately linear for all Se forms and application rates (R²>0.90 for 27 of the 30 experimental units). On average, whole-grain Se increased by 20, 21 and 15μgSekg⁻¹for each gram of Se applied as Na₂SeO₄₍ₐq₎, NPK+Se and CAN+Se, respectively. Grain and stover yields were unaffected by Se applications. An application of 5gSeha⁻¹ to maize crops in Malawi would increase dietary Se intake by 26–37μgSeperson⁻¹d⁻¹ based on national maize consumption patterns. Agronomic biofortification with Se in Malawi is feasible in theory through the existing national Farm Input Subsidy Programme (FISP) if deemed to be economically and politically acceptable.