A study on wheat grain zinc, iron, copper, and manganese concentrations and their relationship with grain yield in major wheat production areas of Iran

Abstract

Iran is a country with different soils and climatic zones that affect the nutrient concentration in the produced wheat. Since wheat is one major component of Iranian diet, this survey was performed to investigate the concentration of micronutrients including copper (Cu), manganese (Mn), iron (Fe), and zinc (Zn) in wheat grains of Iran. For this purpose, a total of 1876 grain samples were collected from the wheat grown lands of Iran and analyzed for the micronutrients. Results revealed that the grain yields were found 5.50 and 2.02 ton ha−1 for irrigated and rainfed wheat, respectively. The average concentration of Zn, Fe, Cu, and Mn in the wheat was 26, 32.76, 34.7, and 5.94 mg kg−1 respectively. The spatial distribution of Zn, Fe, and Mn showed that the wheat produced in the south and southwestern, east and southwestern, and east were more enriched, respectively. While, the wheat produced in the central, south, and southwestern areas contained a higher concentration of Cu. Moreover, results showed that the average concentration of Zn (26 mg kg−1) and Fe (32.76 mg kg−1) was lower than the recommended concentrations for human health (i.e. Zn = 41 mg kg−1; Fe = 57 mg kg−1), which indicates a deficiency of these elements in the wheat grains. Due to the calcareous nature of the soils of Iran, alkaline pH, and low amount of organic matter, the bioavailability of nutrients are low and deficiency symptoms are revealed. Moreover, by increasing grain yield the concentration of grain elements decreases, which shows the effect of new varieties on intensifying the nutrient deficiency. The present study revealed the nutritional status of wheat grown in Iran and confirmed deficiency of Fe and Zn. This study provided information to the decision-makers to overcome this problem by employing proper strategies such as fortification and enrichment.