Objective. To study the influence biopreparations, different in origin and mechanisms of action, on the yield and oil content in oil flax seeds under arid conditions against the background of artificial and natural moistening. Methods. Field, biochemical, calculation and statistical. Results. It has been found that in the conditions of natural moistening of the Southern Steppe of Ukraine, the use of such preparations ass Azofosforin, Ekofosforin, Binoc TK and Bio-gel on oil flax crops, according to the recommendations for seed treatment and sowing in the “herringbone” phase, increases oil yield due to increase in seed yield and, in most cases, the oil content of the seeds. The efficiency of individual preparations was determined by the weather conditions of the growing season. The predominant effect of organic fertilizer Bio-gel on the yield was found, while microbial preparations had a positive effect on both the yield and oil content in flax seeds. The use of Ekofosforin and Binoc TK for seed inoculation increases yields by 0.22 and 0.11 t/ha, and oil content — by 0.5 and 0.4 percentage points, respectively. Double application of the Azofosforin increases the conditional fat yield by 31 % via increasing seed yield by 0.11 t/ha. The use of microbiological preparations and organic fertilizers for seed treatment before sowing and for foliar fertilization in the cultivation of oil flax of Vira variety has a positive effect on yield, oil content in seeds, which increases fat yield by 11.0–57.9 %. Conclusion. The use of biopreparations in the technology of growing oil flax is a basic element of obtaining products for food and medical use. The highest yield (0.99 t/ha) and the highest fat yield (428 kg/ha) in the experiment is provided by pre-sowing seed treatment with organic fertilizer Bio-gel at a dose of 1.5 L/ha. The highest oil content (43.0 %) is provided by foliar treatment of plants with Azofosforin. The use of microbiological preparations Ekofosforin, Binoc TK and Azofosforin for seed treatment increases the yield by 0.08–0.22 t/ha and oil yield by 11.1–12.9 %.
