Soybeans are a cost-efficient crop and the value of their production is very important. The growth of soybean production in recent years has increased significantly, but the potential of this crop is far from being implemented [1]. Cultivation of soybeans in conditions of risky agriculture, where the limiting factors are climatic, mainly it’s a lack of moisture, for high yield is possible only in terms of irrigation [2, 3]. In this context, the search for agrotechnical methods allowing the creation of conditions for crops that maximize the activity of the leaf apparatus of plants is an urgent task. Photosynthesis is the most important factor determining crop capacity [4]. In the course of the photosynthetic activity of plants, the accumulation of organic matter and energy by green plants occurs. Thus, the purpose of our research is the use of growth promoters for photosynthesis and the efficiency of planting soybeans.

The research comprised a fi eld experiment to study assimilation processes when using growth regulators on soybean crops and their effect on capacity.

The plot for fi eld experiments is represented by meadow-black-earth (chernozem) heavy clay loam, suitable and meeting the requirements for the growing conditions of soybeans in terms of hydrophysical and physical and chemical indicators for cultivation with irrigation. The soils are not saline, with no alcali content. Calcium (Ca) predominates in the soil adsorption complex (SAC). Agrochemical parameters of the properties of the soil plough-layer horizon: the content of nitrate nitrogen 27.8 mg/kg, mobile phosphorus — 15.8, mobile potassium 482 mg/kg, humus 3.03 %. The content of the main nutrients in the soil: nitrate nitrogen — GOST 26488-85, mobile phosphorus and exchangeable potassium (according to Machigin) — GOST 26205-91, humus — GOST 26213-91.

The experiment was repeated four times, the plot area was 150 m², and the accounting area was 100 m². In the experiment, the SK Optima soybean variety of an early ripening period with a vegetation period of 113 days. The maximum yield (4.09 t/ha) was obtained in the North Caucasus region [5].