Amur breeding soybean variety evaluation for the content of absolutely essential amino acid threonine

The purpose of the study was to evaluate the content of threonine in the protein of grains of soybean varieties of the All-Russian Soybean Research Institute. Tasks are selection of the most suitable soybean varieties of different ripeness groups, suitable for creating functional products. The object of the study was 26 soybean varieties created by breeders of the Federal State Budgetary Scientific Institution Federal Research Center of the All-Russian Research Institute of Soybean (the Amur Region) from 2003 to 2021: Harmonia, Dauria, Lydia, Lazurnaya, Grazia, Stately, MK 100, Persona, Nega 1, Evgenia, Alena, Bonus, Umka, Pepelina, Kitrossa, Kuhanna, Lebedushka, Intriga, Kruzhevnica, Zhuravushka, Nevesta, Topaz, Sentyabrinka, Zolushka, VNIIS 18, Zolotnica. Laboratory studies of the amino acid composition of soy protein were carried out in 2018-2021 in the testing laboratory of the Federal Research Center of the All-Russian Research Institute of Soybean by the method of IR spectroscopy in the near infrared on an IR analyzer of the FOSS NIRSystems 5000 model (Denmark). Data for 3 years were evaluated, except for varieties VNIIS 18 and Zolotnica, which were studied for 2 years. Analyzes were performed in 3 analytical replicates. Seed selection was carried out from the collection nurseries of the experimental field of the soybean breeding laboratory (Sadovoe village, the Tambov District, the Amur Region) after harvesting. The content of threonine in the protein of soybean grain of the studied varieties ranges from 3.3 to 3.6 % of the total amount of amino acids and averages 3.5 g per 100 g of protein. This is less than in varieties bred in the central regions of the Russian Federation. Despite the fact that the amino acid index for threonine in Amur varieties does not exceed 90 %, this does not at all reduce their value as a source of this amino acid, especially from the point of view of their use in the production of functional products. The highest levels of threonine content were noted for the group of early maturing varieties. Varieties from this group (Kruzhevnica and Zolotnica) can be recommended for the production of functional products.