Influence of irrigation in different phenophases on the chemical composition of soybean grains

Mariya Sabeva1, Alexander Matev1, Katya Uzundzhalieva1, Stanislav Stamatov1, Zlatina Ur1, Bilyana Harizanova-Petrova2, Radost Petrova2 and Nikolay Minev2
1 Agricultural Academy, Institute of Plant Genetic Resources “K. Malkov”, 4122 Sadovo, Bulgaria
2 Agricultural University, 4004 Plovdiv, Bulgaria


Sabeva, M., Matev, A., Uzundzhalieva, K., Stamatov, S., Ur, Z., Harizanova-Petrova, B., Petrova, R. & Minev, N. (2023). Influence of irrigation in different phenophases on the chemical composition of soybean grains. Bulg. J. Agric. Sci., 29 (2), 312–319

The present study aims to determine the influence of single irrigations during the different phenophases of the vegetation period on components of the chemical composition of soybean seeds. Data from a long-term field experiment conducted in the Agricultural University-Plovdiv on alluvial-meadow soil were used. The variants of the experiment are: 1) no irrigation, 2) only the 1st watering, 3) only the 2nd watering, 4) only the 3rd watering, 5) optimum irrigation with three waterings given at pre-irrigation soil moisture 80% FC for the layer 0-60 cm. The results show that the crude protein content is highest when irrigated only during the flowering period. Single irrigations have little effect on the crude fat content of soybean seeds. Watering during flowering increases it between 0.3 and 0.7%. A single watering during the pod formation period (R3-R4) is ineffective in very dry years. It is weakly effective in medium dry years, and its effect increases in more favourable years, increasing the fat content by about 1%. Watering during the period of bean formation provides 64-68% of the maximum yield of fat, and the results for the other phenophases are similar.

Keywords: soybean; irrigation; protein; fat; water deficit

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