One of the priority areas for the development of Agriculture in Ukraine is the stable production of oilseeds. Soy is one of the most important and widespread legumes and oilseeds in the world. It is characterized by a high protein and oil content and high nutritional qualities. Soy seeds contain 30–45 % protein, 13–26% fat, 20–32% carbohydrates, as well as minerals, vitamins, enzymes, etc.
 Without the use of fertilizers, it is impossible to obtain a big soybean harvest. Among the main factors that determine the yield of this crop, fertilizers account for 30 %, varieties – 20 %, weather conditions and plant protection – 15 % each, effective fertility and tillage – 10 % each.
 Therefore, the study of the effect of a combination of metabolically active substances (complexes of vitamin E and ubiquinone-10; vitamin E, 4-hydroxibenzoic acid (PHBA) and methionine; vitamin E, 4-hydroxibenzoic acid (PHBA), methionine and magnesium sulfate growth regulator Vympel on assimilation processes in soybean leaves in the main phases of ontogenesis and its performance is worthy of scientific attention.
 It was observed that pre-sowing treatment of seeds with combinations of metabolically active compounds effectively affected the formation of the number of leaves during all phases of plant growth and development. Thus, when using vitamin E in combination with ubiquinone-10, the maximum number of leaves on soybean plants was formed, exceeding the control indicators at all the studied phases and indicators in the variant with a pennant in the flowering and bean formation phase.
 The use of combinations of metabolically active compounds for pre-sowing seed treatment causes certain changes in the pigment composition of soybean leaves at different phases of ontogenesis. It was found that pre-sowing treatment of soybean seeds with a combination of vitamin E + ubiquinone-10 substances allowed to achieve the maximum result, namely, to increase the content of the sum of chlorophylls A and b in soybean leaves to 25.54 mg/g of raw mass, which is 35.42 % more than the control and 16.55 % more than in the variant with Vympel. Pre-sowing treatment of soybean seeds with combinations of substances vitamin E + ubiquinone-10, vitamin E + PHBA + methionine allowed to increase the content of the sum of chlorophylls a and b in soybean leaves by 9.97 mg/g and 8.35 mg/g of raw mass and in the flowering phase. The maximum content of chlorophylls a and b was achieved during the bean formation phase.
 Pre-sowing treatment of soybean seeds with combinations of metabolically active substances vitamin E + ubiquinone-10, vitamin E + methionine + PHBA contribute to the maximum realization of photosynthetic productivity, so further study of the effect of the above substances on leguminous crops is promising.
 Pre-sowing treatment of soybean seeds with metabolically active compounds can be used as elements of technology in the cultivation of legumes.
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