The relationship between productivity and hydrothermal conditions for growing soybeans on rainfed lands in the Middle Volga region

Relevance . One of the most important factors that determine the effective cultivation of soybeans in the Middle Volga region is the use of modern highly productive varieties adapted to growing conditions. To create a competitive variety, it is important to select sources that are adapted to the environmental factors of a particular region. Methods . Field experiments were carried out according to generally accepted methods. All counts and observations were carried out according to the Methodological Guidelines for Studying the Collection of Legumes. In 2016–2019, 36 early maturing and medium early maturing varieties of soybeans of various ecological and geographical origin, as well as breeding material created in local conditions, were studied in the breeding nursery. Results . It was found that the duration of the growing season over the years of study was largely determined by the duration of the flowering — ripening period (r = 0,96). Correlation analysis showed that a significant role in the formation of the yield of soybeans is played by hydrothermal conditions that develop during the generative phase of plant development. There is a high correlation between the level of yield and the average daily temperature and the sum of active temperatures (r = 0,79–0,82) during the flowering — ripening period. In the breeding nursery, the cultivars that most fully realize the genetic potential and reliably exceed the standard in productivity by 12,0–22,0% were identified: k-177, k-445/2 and IHAR-NK 88/2.