In connection with the study of the effect of the succulent seed coat (sarcotesta) of Jasminum fruticans L. (Oleaceae) on the viability of seeds, a study of the germination of test objects at different volume concentrations ( σВ ) of mature seed extract was conducted 1; 0,75; 0,5; 0,25. The test objects were radish seeds ( Raphanus sativus var. radicula Pers.) ‘Zhara’ and watercress ( Lepidium sativum L.) ‘Zabava’ (Brassicaceae). The seeds were seeding on distilled water as the control. The volume content of phenolic compounds in the obtained extract solutions of various dilutions was determined. A qualitative reaction to tannins contained in J. fruticans seed extract was performed. The qualitative reaction confirmed the presence of a condensed group of polyphenolic compounds in the extract. A decrease in the germination of radish and watercress seeds was found at extract concentrations of 0,25 (0,31 mg/ml PC), 0,75 (0,92 mg/ml PC) and 1 (1,22 mg / ml PC). When σВ =0,50 (0,61 mg/ml PC), the germination of radish and watercress increases, but the indicators do not have a statistically significant difference compared to the control. It is shown that the formation of abnormal sprouts of test objects increases with an increase in the volume concentration of the extract, with the exception of the variant σВ =0,50. Radish has more than 60% of abnormal seedlings are associated with hypocotyl deformation. Watercress seedlings have hypocotyl abnormalities and root abnormalities (more than 50%) The observed pattern of changes in the germination of test objects seeds from the concentration of J. fruticans water seed extract indicates its allelopathic properties. The presence of phenolic compounds in the sarcotesta of J. fruticans indicates its regulatory function in the process of seed development.