Genotype x Environment Interactions for Mineral Concentration in Grain of Organically Grown Spring Wheat

Genotype x environment (GxE) interactions for Ca, Cu, Fe, Mg, Mn, P, and Zn concentrations are not well understood, particularly in the context of organic farming systems. The objectives of this study were to: (i) investigate GxE interactions for mineral nutrient concentration in organically grown wheat; and, (ii) assess whether grain mineral concentration is a broadly or narrowly adapted trait when grown in contrasting environments over time. We evaluated 18 spring wheat (Triticum aestivum L.) cultivars on three organic farms in Washington State for mineral concentration and for grain yield in 2008 and 2009. The GxYear (Y) interactions were found for grain yield and all minerals except Fe, Mn, and P and GxLocation (L) interactions were found for grain yield and all minerals except Fe. The GxE (GxLxY) interactions were found for grain yield and all minerals except for Mn. Grain yield was not consistently correlated with mineral nutrients across years and locations. Among minerals, Mg: P, P: Zn, and Mg: Zn were positively correlated in at least five of six site-years, suggesting the potential for simultaneous selection of these minerals. Grain mineral concentrations of Cu, Fe, and P showed relatively broad adaptation across years when compared with Ca and Mg concentrations. Fewer cultivars were broadly adapted spatially than temporally for stable levels of mineral concentration. Several cultivars had relatively high concentrations of two or more minerals across locations, indicating the potential for farmer utilization of broadly adapted cultivars and varietal blends that will significantly increase grain mineral concentration.