Biofortification of Common Wheat Grains with Combined Ca, Mg, and K through Foliar Fertilisation

Common wheat grains are characterised by low concentrations of Ca, K, and Mg, which can be partially removed with the bran during milling processes. This preliminary study investigated the effects of foliar fertilisation at the earing stage with nitrates of Ca, Mg, and K contemporarily, together with a small amount of urea and protein hydrolysate as potential carriers, in two contrasting common wheat varieties, i.e., Solehio (medium proteins content) and Vivendo (high proteins content). Based on the preliminary grain-to-straw concentration ratio of these minerals, two biofortification targets were applied in order to increase their grain contents by +20% and +40%, in comparison with untreated controls. Here, we demonstrate that the highest fertilisation dose was effective in increasing grain K by 13% and Mg by 16% in Vivendo, and Ca by 7% in Solehio, with no boosting effects of the co-formulants urea and protein hydrolysate. In addition to some qualitative benefits due to nitrates supply, negligible phytotoxicity symptoms were observed, as revealed by the NDVI vegetational index dynamics. Although the biofortification target was not fully achieved, this study firstly reports the possibility to increase at the same time Mg and K, and to a lower extent Ca in wheat grains. It is concluded that efficient multiple biofortification should consider a variety-depend response, while further studies are necessary to investigate the effects of different fertilisation timings and doses for improving the poor mineral translocation to the grains