Are synthetic hexaploids a means of increasing grain element concentrations in wheat?

Element concentration in wheat grains is an important objective of plant breeding programs. For this purpose, synthetic hexaploid lines (Triticum durum x Aegilops tauschii) have been identified as potential sources of high element concentration in grains. However, it is not known if these lines reach higher element concentrations in grains as the consequence of a dilution effect due to lower grain yield. In addition, most of the studies carried out with these lines did not evaluate above-ground element uptake. The objective of this study was to improve understanding of grain element concentrations as a function of grain yield, element uptake and biomass and element partitioning to grains in synthetic and conventional cultivars of wheat. One experiment with two standard sowing dates was carried out under field conditions. Biomass, grain yield, and macronutrient (Ca, Mg, K, P and S) and micronutrient (Cu, Fe, Mn and Zn) concentrations in grains and vegetative tissues were measured in two cultivars and one synthetic (chosen from ten lines). The synthetic showed higher element concentration in grains, e. g. between 25 and 30% for Fe, Mn and Zn across sowing dates, than cultivars while grain yield was similar or lower, depending on the sowing date. On the contrary, the synthetic showed lower concentration of Ca in grains. This line showed also higher uptake of Fe, Mn, K and P than cultivars. The superior grain element concentration of the synthetic line was not only due to a dilution effect but also to a higher uptake efficiency. Therefore, synthetics would be a valuable source of germplasm for increasing element grain concentration, at least in this case for Fe, Mn, K and P.