The article presents the results of research on the influence of organic fertilizers, biostimulants, and biofungicides on biometric parameters of growth, development, and yield of potato under the conditions of the Polissia zone of Ukraine. The studies were conducted in 2023–2025 within a long-term field experiment in a four-field crop rotation on sod-podzolic sandy loam soil. The effect of biological preparations was studied against the background of green manure incorporation of white mustard and in combination with cattle manure application at a rate of 40 t/ha. It was established that the use of biostimulants and biofungicides increased field emergence from 86.2–88.4 % in the control to 97.3 % in the treatment with VIT-ORG VG and Mycohelp on the organic fertilization background. Pre-planting tuber treatment prolonged the “planting–emergence” period by 1–4 days and extended the overall vegetation period by 5–8 days. A positive effect on biometric traits was observed: plant height increased by 5.5–18.1 %, the number of stems per plant by 0.2–0.4, and stem density by 13.8– 37.6 %. Yield varied significantly across years, ranging from 19.6 to 26.7 t/ha under green manure and from 23.5 to 32.0 t/ha with manure application. On average, yield increases due to biological preparations reached 2.7–14.8 % and 5.1–18.7 %, respectively. The highest yields (31.8–32.3 t/ha) were obtained with the combined application of green manure (white mustard), cattle manure (40 t/ha), and biopreparation complexes (Biogran + StimPure AA Liquid + Mycohelp; VIT-ORG VG + Mycohelp). The effect of different biofungicides on yield was statistically insignificant. The results confirm the effectiveness of combining organic fertilizers with biostimulants and biofungicides as an important component of potato cultivation technology under the conditions of Polissia in Ukraine.

Key words: potato, organic fertilizers, green manure, biostimulants, biofungicides, biometric traits, yield.