Efficiency of selenium biofortification of spring wheat: the role of soil properties and organic matter amendment

The effect of soil selenate application to two different soils (Phaeozem and Cambisol) on biomass yield and selenium (Se) uptake by spring wheat (Triticum aestivum L.) was investigated in a pot experiment. Additionally, organic amendment (fugate, i.e. liquid by-product from the biogas plant) was applied to assess (i) the effect of organic matter on the bioavailability of Se and (ii) the fugate (containing 2.3 mg/kg of Se) as a potential source of Se for plants. Selenium was applied at two levels: 6.4 µg/kg (Se1) and 32 µg/kg (Se2) of soil. The efficiency of biofortification and the distribution of selenium within individual plant compartments were assessed in this case. The highest Se contents in the grain were achieved in the treatments receiving NPK fertiliser together with selenate, 455 µg/kg (Se1) and 2 721 µg/kg (Se2) when wheat was planted in Phaeozem. Fugate in co-application with selenate significantly reduced Se content in wheat plants as compared to treatments enriched solely with selenate. The lower Se contents in the wheat plants growing in Phaeozem were due to the biodilution effect, whereas in Cambisol, the decrease in wheat Se uptake was not clearly driven by a particular factor.