The article considers the effect of growing process elements on common ryegrass seed yield (Lolium perenne L.). The research indicates that fertilizer application has the greatest effect on plant height. During 2018-2019 the highest plants could be observed on the plots with N60P60K60 application in Svyatoshyns'kyy variety (71 cm) and the lowest – in Andriana 80 variety (59 cm). The years of experimental research proved that, on average, variants with N60P60K60 and N60P60K60 + Quantum-Grain application provided the highest seed yield in Svyatoshyns'kyy (0,68-0,72 t/ha) and Ruslana (0,64-0,69 t/ha) varieties. Andriana 80 variety showed the lowest yield indices (0,62-0,68 t/ha) in case of similar experimental variants. The application of liquid complex fertilizers as top-dressing increased common ryegrass seed yield of Andriana 80 variety on average by 8% and Svyatoshyns'kyy variety by 6% during two years of research. Common ryegrass plants demonstrated the longest inflorescences in case of complete mineral fertilizer application: Ruslana variety 18,1-19,8 сm and Svyatoshyns'kyy variety – 23,3-25,2 cm. Andriana 80 variety had the shortest inflorescences – 17,9-19,5 сm. The seed quantity ranged from 52 to 72 depending on variety and fertilizers. Svyatoshyns'kyy variety indices exceeded Andriana 80 variety indices on average by 11% and variants with complete mineral fertilizer application by 14% as compared with variants without fertilization. The weight of 1000 seeds ranged from 1,4 to 2,5 gm depending on variety and fertilizers. Svyatoshyns'kyy variety indices exceeded Andriana 80 variety and Ruslana variety indices on average by 28%. From among common ryegrass seedlings, Svyatoshyns'kyy variety provided the highest operating profit. Prospects for future research is to research the impact of liquid complex fertilizers on yield productivity and the quality of seeds

Keywords: common ryegrass, seed yield, biometric characteristics of reproductive organs, operating profit