Zinc Biofortification in the Grains of Two Wheat (Triticum aestivum L.) Varieties Through Fertilization

Abstract

We examined the effects of zinc (Zn) fertilization on wheat, focusing on yield and biofortification in the grains of two wheat varieties. Five Zn rates, i.e., 0, 1.5, 3.0, 4.5, and 6.0 kg ha⁻¹ applied as ZnSO₄·7H₂O (23% Zn), and two wheat varieties, i.e., ‘BARI Gom-25’ and ‘BARI Gom-26,’ were used in the study. All plant characteristics, except 1,000-grain weight and plant height, i.e., tillers plant⁻¹, spikes m⁻², spike length, spikelets spike⁻¹, and grains spike⁻¹, were significantly influenced by Zn fertilization. Treatment with 3.0 kg Zn ha⁻¹ (Zn_3.0) produced the highest grain yield (3.90 t ha⁻¹), which was statistically similar to Zn_4.5 and Zn_6.0 treatments. The control treatment (Zn₀) produced the lowest grain yield (2.99 t ha⁻¹). The concentrations of N, Zn, and Fe were significantly and positively influenced by Zn treatment. The crop varieties did not differ significantly in terms of N and Zn concentrations. However, the grain Fe concentration was remarkably higher in ‘BARI Gom-26’ than in ‘BARI Gom-25.’ The grain N and protein concentrations increased linearly with the Zn application rate. The grain Zn concentration increased with Zn application rates in a quadratic line, indicating that the concentration of Zn in wheat grain increased with Zn fertilization; however, it attained a maximum value in the Zn_4.5 treatment, after which it declined with higher rate of Zn application. The application of Zn at the rate of 4.5 kg ha⁻¹ resulted in the highest Zn fortification (39.7 µg g⁻¹) in wheat grains, which was 17.1% higher than in the control treatment. The response curve showed that 4.62 kg ha⁻¹ for ‘BARI Gom-25’ and 3.94 kg ha⁻¹ for ‘BARI Gom-26’ were the optimum Zn rates for achieving higher wheat grain yield. However, 5.5 kg ha⁻¹ was the optimum Zn rate for obtaining higher Zn fortification in wheat grains.