Biofortification of Silage Maize with Zinc, Iron and Selenium as Affected by Nitrogen Fertilization

Abstract

Agronomic biofortification is one of the main strategies for alleviation of micronutrient deficiencies in human populations and promoting sustainable production of food and feed. The aim of this study was to investigate the effect of nitrogen (N)fertilization on biofortification of maize crop (Zea mays L.) with zinc (Zn), iron (Fe) and selenium (Se) grown on a micronutrient deficient soil under greenhouse conditions. Factorial design experiment was set under greenhouse conditions. The experiment consisted of two levels of each N, Zn, Fe and Se. The levels for N were 125 and 250 mg N kg^-1 soil; Zn were 1 and 5 mg Zn kg^-1 soil; levels of Fe were 0 and 10 mg Fe kg^-1 soil; levels of Se were 0 and 0.02 mg Se kg^-1 soil. An additional experiment was also conducted to study the effect of the Zn form applied as a ZnO or ZnSO₄ on shoot growth, shoot Zn concentration and total shoot Zn uptake per plant. Shoot Zn concentrations increased by increasing soil Zn application both with ZnSO₄ and ZnO treatments, but the shoot Zn concentration and total Zn uptake were much greater with ZnSO₄ than the ZnO application. Under given experimental conditions, increasing soil N supply improved shoot N concentration; but had little effect on shoot dry matter production. The concentrations of Zn and Fe in shoots were significantly increased by increasing N application. In case of total uptake of Zn and Fe, the positive effect of N nutrition was more pronounced. Although Se soil treatment had significant effect, N application showed no effect on Se concentration and accumulation in maize shoots. The obtained results show that N fertilization is an effective tool in improving the Zn and Fe status of silage maize and contribute to the better-quality feed.

Keywords: biofortification; maize; micronutrients; nutrient uptake; plant nutrition.

Figure 1

Zinc deficiency symptoms on young leaves of maize plants.

Figure 2

Correlation between shoot Zn and Fe concentrations under different N soil supply. Data for 25. days old maize plants. N rates: low (125 mg of N/kg of soil), (---, ■), and adequate (250 mg of N/kg of soil), (---, ♦).

Figure 3

Correlations between Zn, Fe and N concentrations in maize shoot under different Zn soil supply. (A) Low Zn soil supply. (B) Adequate Zn soil supply. Data for 25 days old maize plants. Fe maize shoot concentration (---, ■), Zn maize shoot concentration (---, ▲).

Figure 4

(a) Effects of increasing soil Zn supply in form of ZnO on growth of maize plants on a Zn-deficient calcareous for 20 days (bottom), 27 days (middle) and 35 days (top). (b) Effects of increasing soil Zn supply in form of ZnSO₄ on growth of maize plants on a Zn-deficient calcareous for 20 days (bottom), 27 days (middle) and 35 days (top). Zinc has been applied at the rates of 0, 0.5, 1, 2.5 and 7.5 mg Zn kg⁻¹ soil in form of ZnO and ZnSO4.