Crude Protein Accumulation in Vegetable Soybean Samples Grown in the Central Region of the Non-Chernozem Soil Zone

— The content of crude protein in leaves and seeds of vegetable soybean, an important legume crop used in a functional and healthy nutrition, has been evaluated by a spectrophotometric analysis. Breeding forms of soybean were grown on an experimental field and in a greenhouse of the Federal Scientific Vegetable Center (Moscow oblast). In this 3-year work, the crude protein accumulation in seeds of vegetable soybean at the R8-stage stage under conditions of the Central region of the Non-Chernozem Soil Zone of Russia (55th parallel north) were first studied. No significant difference between the vegetable and oil-seed soybean forms was observed in relation to the protein content in leaves at the R6-stage phase; the average value for vegetable samples was 8.1%. At this phase, the level of protein accumulation in seeds of all samples was almost equal (27.5–28.4%). According to the data of 3-year observations, vegetable soybean accumulated the higher total protein (+15.7% in relative values) at the R8-stage phase, which may be explained by hereditary factors. The maximum crude protein content in seeds was observed in breeding lines Obrazets A, Hidaka, and Cha Kura Kake; the average value for these lines reached 47.4% in absolute units. Under studied conditions, a significant accumulation of crude protein was observed in leaves and seeds of vegetable soybean during both phases of generative development, which may provide great prospects for the use of these samples in the production of functional food products with a high protein content.