Bacterial Seed Inoculation and Row Spacing Affect the Nutritional Composition and Agronomic Performance of Soybean

Sowing of bacterial inoculated seeds and using different cultivar-specific row spacing are 2 well-known agricultural practices in soybean production. However, the connection between different bacterial seed inoculations and row spacing has not previously been investigated in a single study. A 3-year field experiment (2015–2017) was carried out on soybean cv. ES Mentor to assess the effect of 4 rhizobia inoculation treatments (un-inoculated control, C; factory-inoculated seed, F; fresh pre-sowing seed treatment with commercial inoculant, I; and a combination of treatments F and I, FI) and 3 row spacings (12.5 cm, 25 cm and 37.5 cm) on the protein, oil, crude fibre and ash content. The seed, protein and oil yields were determined as well as a thousand seed weight, plant height, pod number and harvest index. There was no interaction between plant spacing and inoculation; however, the inoculation treatments enhanced protein content of seeds by 1.2–1.7%, and increased yields of seed, protein and oil by a maximum of 6.8%, 8.3% and 5.9%, respectively, compared to the un-inoculated control, which produced an average seed yield of 4098 kg/ha. The inoculation treatments also had a moderate influence on biometric measurements. Row spacing had a pronounced effect on seed, protein and oil yields, with plants in 12.5 cm and 25 cm row spacings generating higher yields than those in 37.5 cm row spacings. Correlation analysis showed a significant positive association between seed yield and pod number, and a significant negative correlation between protein and oil content.