The aim of the study was to evaluate the effect of biostimulants enhancing plant growth and development, i.e. organic stimulator based on metal sulphates, Bacillus subtilis, humic acids, on the chemical composition and level of bioactive compounds in garlic leaves, stems, and bulbs. The study was conducted in three growing seasons on the 'Ornak' winter garlic cultivar. The propagating material was treated in solutions of the biostimulants and after emergence the plants were sprayed with the

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... ucts three times. The most valuable edible organ proved to be the leaves, which contained the most protein, fat, and mineral components expressed as ash, were the richest source of fibre, vitamin C, and polyphenols, and also had the highest antioxidant activity among the organs tested. The nutritional value of the stems was comparable to that of the bulbs, and the level of polyphenols and antioxidant activity were even higher. The use of the growth and development biostimulants influenced the chemical composition of the garlic, but the effect was modified by the course of weather in different years of the research and also depended on edible organ. On average for years and organs all biostimulants increased the level of protein, minerals expressed as ash and enhanced antioxidant activity, whereas decreased the level of total carbohydrates.