The study was conducted in 2012–2015. A small-area field experiment was performed at the Agricultural Experiment Station in Tomaszkowo (53°42'40.8"N 20°26'04.7"E) owned by the University of Warmia and Mazury in Olsztyn. The aim of this experiment was to determine the effects of a cultivar, nitrogen dose and harvest time on the content of nitrogen (N), phosphorus (P) and potassium (K) in the biomass of perennial ryegrass. The content of N, P and K in biomass was determined as follows: N - by the Kjeldahl method, P and K – by flame photometry. During the three-year study, the diploid cultivar Bajka accumulated higher amounts of N, whereas the tetraploid cultivar Baronka accumulated significantly higher amounts of K. The tested perennial ryegrass cultivars did not differ in P content, determined on a dry matter basis. It was found that the N content of plants was higher when perennial ryegrass was harvested at noon and in the afternoon. The reverse was observed with regard to K accumulation. Perennial ryegrass biomass harvested in the morning was characterised by significantly higher K content than the biomass harvested at noon and in the afternoon. Harvest time had no influence on P concentrations in the analysed cultivars. The accumulation of N and K in perennial ryegrass was affected by N fertilisation. In both cultivars, the N and K content of plants was significantly higher in treatments fertilised with N, whereas no differences were found between N doses. A minor increase in the P content of the analysed cultivars occurred only when the N dose was doubled.

25.2.2020