Influence of nitrogen, sulphur, and selenium foliar application on yield and accumulation of selenium in spring wheat grains (Triticum aestivum L.)

The study is focused on the evaluation of selenium, nitrogen and sulphur effects on yield, macro- and micronutrient content (N, P, K, Ca, Mg, S, Zn, Fe, Mn, Cu) and quality (Se content, starch, fibre, ash and fat) in wheat grain. Small-plot field experiments (10 m² each plot) were established on loam to clay loam mollic soil with total Se content 0.21–0.22 mg/kg in eliezovce on the land of the Central Control and Testing Institute in Agriculture of the Slovak Republic. The effect of growing season on two sources of selenium, in the form of sodium selenite (Na₂SeO₃ · 5 H₂O) and sodium selenate (Na₂SeO₄), was monitored during the growth phase BBCH 29 (the end of the tillering phase) in a two-year experiment. The experiment included six foliar treatments in four repetitions, which were differentiated as follows: T1 – 30 kg N/ha; T1 Se0₃^2– – 30 kg N/ha and 20 g Se/ha; T1 Se0₄^2– – 30 kg N/ha and 20 g Se/ha; T2 – 30 kg N/haand 10 kg S/ha; T2 Se0₃^2– – 30 kg N/ha, 10 kg S/ha and 20 g Se/ha; T2 Se0₄^2– – 30 kg N/ha, 10 kg S/ha and 20 g Se/ha.A statistically significant difference in yield was found between the growing seasons. Statistically non-significant impact of treatments on achieved yields was found. The highest average Se content in grain, 0.90 ± 0.28 mg/kg, was achieved on treatment T2 Se0₄^2–. The application of sodium selenite appeared to be less effective than selenate form in the evaluation of average Se content in grain, where statistically significantly higher Se contents (T1 Se0₄^2– 0.78 ± 0.22 mg/kg; T2 Se0₄^2– 0.90 ± 0.28 mg/kg) were found after selenate application. The application of two types of fertilisers and two forms of selenium did not significantly increase the content of N, P, Mg, and S in grain. The Fe content in the grain was increased by treatment T2 Se0₃^2–. The application of sodium selenate compared to sodium selenite significantly increased the starch content (T1 Se0₄^2– 56.39 ± 4.44%; T2 Se0₄^2– 55.87 ± 4.05) in the grain of spring wheat.