Impact of zinc biofortification on yield and nutritional quality of wheat grain

Abstract:

"You cannot fix a mineral deficiency in the diet by fixing only the field," a regional nutrition officer once remarked, and this research set out to test how much of that gap agronomic and genetic approaches together can actually close for wheat grown around Yaounde, Cameroon. Five zinc management strategies, untreated control, soil-applied zinc sulphate, single foliar zinc spray, split foliar zinc spray (two applications), and a zinc-efficient wheat variety without any zinc fertilization, were compared over two seasons for their effect on grain yield and grain zinc concentration. Split foliar zinc application produced the highest grain zinc concentration at 44 mg per kg, more than 80% above the untreated control's 24 mg per kg, and also delivered the highest grain yield among the five treatments. The zinc-efficient variety, grown without any zinc fertilizer input, still achieved grain zinc concentration of 41 mg per kg, statistically comparable to the split foliar treatment, demonstrating that genetic zinc efficiency can substitute for fertilizer input to a considerable degree. Soil-applied zinc sulphate underperformed both foliar approaches on grain zinc concentration despite its higher raw application cost, consistent with known limitations in soil zinc availability under the site's near-neutral pH conditions. Source-contribution analysis indicated foliar application accounted for the largest share of the zinc biofortification achieved across all treatments combined, ahead of genetic efficiency and soil-based approaches. These findings support split foliar zinc application as the most yield- and quality-effective single strategy tested, while highlighting zinc-efficient varieties as a genuinely competitive input-free alternative worth wider promotion where fertilizer access or cost is a binding constraint.