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<sup>−1</sup> applied as ZnSO<sub>4</sub>·7H<sub>2</sub>O (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<sup>−1</sup>, spikes m<sup>−2</sup>, spike length, spikelets spike<sup>−1</sup>, and grains spike<sup>−1</sup>, were significantly influenced by Zn fertilization. Treatment with 3.0 kg Zn ha<sup>−1</sup> (Zn<sub>3.0</sub>) produced the highest grain yield (3.90 t ha<sup>−1</sup>), which was statistically similar to Zn<sub>4.5</sub> and Zn<sub>6.0</sub> treatments. The control treatment (Zn<sub>0</sub>) produced the lowest grain yield (2.99 t ha<sup>−1</sup>). 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<sub>4.5</sub> treatment, after which it declined with higher rate of Zn application. The application of Zn at the rate of 4.5 kg ha<sup>−1</sup> resulted in the highest Zn fortification (39.7 µg g<sup>−1</sup>) in wheat grains, which was 17.1% higher than in the control treatment. The response curve showed that 4.62 kg ha<sup>−1</sup> for ‘BARI Gom-25’ and 3.94 kg ha<sup>−1</sup> for ‘BARI Gom-26’ were the optimum Zn rates for achieving higher wheat grain yield. However, 5.5 kg ha<sup>−1</sup> was the optimum Zn rate for obtaining higher Zn fortification in wheat grains.
Highlights
Wheat is the second-most important cereal crop in Bangladesh, where more than 50% of the wheat consumed is imported (Hossain & Teixeira da Silva, 2013)
The aim of the present study was to examine the effects of Zn fertilization and the variety used on the yield and biofortification of wheat grains
The response curve showed that 4.62 kg ha−1 for ‘Bangladesh Agricultural Research Institute (BARI) Gom 25’ and 3.94 kg ha−1 for ‘BARI Gom 26’ were the optimum Zn rates for achieving the maximum grain yield (Figure 2)
Summary
Wheat is the second-most important cereal crop (after rice) in Bangladesh, where more than 50% of the wheat consumed is imported (Hossain & Teixeira da Silva, 2013). Increasing cropping intensity (143% in 1971–1972 and 191% in 2014–2015) coupled with increasing cultivation of modern high yielding varieties (HYVs) has decreased soil fertility and increased micronutrient deficiencies in Bangladesh (Uddin et al, 1981), where more than 70% of cultivated soils are now. Wheat grains are typically low in Zn (Cakmak, 2010; Cakmak & Kutman, 2018), and consumption of low-Zn wheat-based products can lead to Zn deficiency (Ozturk et al, 2006). Previous research has demonstrated the possibility of overcoming Zn deficiency by externally applying Zn to growing crops, which can improve crop productivity (i.e., yield) (Cakmak, 2008, 2010; Cakmak & Kutman, 2018). For the Zn-biofortification of wheat grains, it is necessary to maintain a satisfactory level of Zn and water in the soil during the reproductive stage of wheat, at the grain-filling stage
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