Modification of the Mineral Quality of Wheat After the Application of Selenium and Sulfur

The mineral composition of cereals is one of the key indicators of the quality of agricultural raw materials, determining both nutritional value and technological and processing properties. Complex interactions between nutrients, especially sulfur and selenium, can significantly modify the accumulation of macroelements in plant tissues. The aim of the study was to assess the effect of different doses of sulfur (S₁-15 kg S ha^-1 and S₂-30 kg S ha^-1) and selenium (Se₁-10 g Se ha^-1 and Se₂-20 g Se ha^-1), as well as the timing of selenium application, on the phosphorus, potassium, calcium and magnesium contents in the grain and straw of spelt and common wheat. The results obtained indicate clear interspecies differences and a non-linear, often species-specific response to selenium doses. In common wheat grain, the application of selenium at two doses increased potassium and magnesium contents by 4-9% and 4-11%, respectively, and it reduced calcium content by 14-18% in spelt wheat grain. In spelt wheat straw, selenium application resulted in an 11% decrease in potassium content and an 8-10% decrease in calcium content. In common wheat, on the other hand, the straw responded with a 17% (Se₁) and 13% (Se₂) increase in magnesium content, accompanied by an 8-10% decrease in potassium content. Sulfur exhibited species-specific effects. In spelt wheat straw, it increased phosphorus content by 5-10%, calcium by 11% and magnesium by 15%. In common wheat straw, sulfur also reduced potassium accumulation by 5% and calcium by 23% (S₁) and 9% (S₂). The timing of selenium application modified the results of their content, but did not show a universal reaction pattern: earlier application increased the P content in spelt straw, while later application promoted an increase in Ca content in common wheat grain.