Combined Zinc and Selenium Biofortification of Durum Wheat in the South-West of Spain

Micronutrient malnutrition, often caused by the low bioavailability of zinc (Zn) and selenium (Se) in soil, poses serious health risks worldwide. To address these deficiencies, this study evaluated the efficacy of combined Se and Zn fertilization in durum wheat (Triticum durum) through a two-year field experiment conducted under semi-arid Mediterranean conditions. The experimental design was a split-split-plot, considering the growing season (2017/18 and 2018/19) as the main plot, an initial soil application of Zn (50 kg ZnSO4-7H2O ha−1 vs. no Zn) as the subplot, and different foliar treatments as the sub-subplot factor: no application (0F), 10 g Se ha−1 (SeF), 8 kg ZnSO4-7H2O ha−1 (ZnF), and a combination of ZnF + SeF. While Zn soil application resulted in a 16% increase in both grain and straw yields, the combined Zn and Se foliar application resulted in a significant 15% increase in grain yield, as well as for the highest concentrations of Zn (by 1.44- and 7.38-fold in grain and straw, respectively) and Se (by 3.41- and 4.41-fold in grain and straw, respectively). These results indicate that durum wheat is a promising crop for biofortification initiatives that could contribute to reducing Zn and Se deficiencies in human diets and livestock feed in the Mediterranean region.