Formation and functioning of the symbiotic apparatus of soybean depending on the sowing method in conditions

Purpose. To study the influence of the sowing method with different row spacing widths on the formation and functioning of the symbiotic apparatus of soybean varieties, selected by the Institute of Feed Research and Agriculture of Podillia of NAAS, in particular Titan, Pallada, Kobuko, on gray forest soils. Methods. Systematic method, field in combination with visual, measuring and mathematical, statistical ones, monolith method. Results. During 2022-2024, the varietal reaction of soybean varieties Titan, Pallada and Kobuko to the sowing method with different row spacing widths (15, 30, 45 cm) was established. It was found that the row spacing width influenced the formation of the symbiotic apparatus of soybean, and subsequently its functioning. In the Titan and Kobuko varieties, the maximum total number of nodule bacteria (76.1 and 71.9 pcs/plant), the number of active nodule bacteria (72.1 and 68.3 pcs/plant) and their weights (1.09 and 1.08 and 0.92 and 0.91 g/plant respectively) were noted when sowing in rows with a row spacing of 15 cm, while in the Pallada variety, the maximum total number and number of active nodule bacteria, respectively, wer e 72.0 and 68.6 pcs/plant and their weights were 0.98 and 0.97 g/plant – when sowing in rows with a row spacing of 30 cm. These variants also showed the maximum indicators of total and active symbiotic potentials: in the Titan variety, respectively, 30.22 and 27.28 thousand kg•day/ha, in the Pallada variety – 29.77 and 26.54 thousand kg•day/ha, in the Kobuko variety – 27.37 and 24.08 thousand kg•day/ha. Conclusions. The obtained research results showed that the formation and functioning of the symbiotic apparatus of soybean varieties significantly depended on the sowing method or row spacing. Based on the correlation-regression analysis, strong feedback relationships were established between the number of active nodule bacteria (r = – 0.713), the mass of active nodule bacteria (r = –0.649), active symbiotic potential (r = –0.714) and row spacing.