Field experiments with spring wheat (Triticum aestivum L.) were carried out at the Experimental Station of Vytautas Magnus University, Agriculture Academy in Lithuania. Spring wheat was dressed with N90P90K116  at sowing and N60 was applied at the stem elongation stage. Liquid amide (NH2) nitrogen fertilizer with magnesium and sulphur was applied either at the tillering stage or at the stem elongation stage. The experiment treatments (nutrient doses in kg ha-1): 1) Control; 2) 0.3 Mg + 0.4 S + 1.1 N (F1); 3) 0.6 Mg + 0.8 S + 2.2 N (F2); 4) 0.9 Mg + 1.2 S + 3.3 N (F3); 5) 1.2 Mg + 1.6 S + 4.4 N (F4); 6) 3.0 Mg + 4 S + 11.0 N (F5). Liquid fertilizer applied at the spring wheat’s tillering stage in the soil with a moderate status of magnesium and sulphur did not significantly change the content of chlorophyll a in wheat leaves within 10 days after application. A significant effect of this fertilizer on the chlorophyll a content was identified when spring wheat at the stem elongation stage had been treated with F2 – F5 (2014) and F1–F5 (2015) fertilizer doses. Significant effect on the carotenoid content was recorded in the plots applied F3 (2014) and F2 – F4 (2015) doses. A significant increase in the nitrogen content in wheat plants was observed in the treatments fertilized with F1 – F5 doses at the tillering stage and those applied F3 – F5 fertilizer doses at the stem elongation stage. The relationship between the nitrogen content in wheat plants and fertilizer doses was strong and significant. Significant grain yield increases were obtained in the treatments fertilized with F3 – F5 doses ates at tillering and those fertilized with F2 and F3 doses at the stem elongation stage. Statistically significant correlations between fertilizer doses and grain yield were determined for both growth stages at which the fertilizer had been applied, i.e. at tillering and at stem elongation. Fertilizers tended to increase the grain protein content; however, a significant increase in the grain protein content was observed only in the treatment fertilized with F3 dose at stem elongation.

25.1.2020