Historical shifts in the seed mineral micronutrient concentration of US hard red winter wheat germplasm

The yield of wheat (Triticum aestivum L. em. Thell) has greatly improved through breeding, but it is not known how this has affected seed micronutrient content. In the present study, the iron (Fe), zinc (Zn), copper (Cu), and selenium (Se) content of seed of 14 US hard red winter wheat varieties from production eras spanning more than a century was measured. The seed that was analyzed was obtained from a replicated field trial conducted at two locations in Kansas. The Fe, Zn, and Cu content was obtained by inductively coupled plasma emission spectroscopy (ICPES) and Se content was obtained by hydride-generated atomic absorption spectrometry (HG-AAS). Significant effects of location on micronutrient content of seed were observed. Similarly, depending on the micronutrient, significant differences in seed micronutrient content between varieties were detected at one or both locations. A significant negative regression of seed Zn content on both yield and variety release date was observed at both locations, while seed Fe content exhibited a significant negative regression on yield and variety release date at one location. Regression of seed Se content on variety release date was significant and negative at one location. These results suggest that genetic gains in the yield of US hard red winter wheat have tended to reduce seed Fe, Zn, and Se concentrations. However, the extent to which this effect manifests itself is influenced by environmental effects. Published in 2006 by John Wiley & Sons, Ltd.