Identifying Optimum Planting Populations for Midwestern US Food-Grade Soybean Production

November 11, 2019 - Thomas Siler, <>, <>

The increasing demand for soybean (Glycine max (L.) Merr.) used for human consumption has created an expanding market for food-grade soybean. However, food-grade soybean production differs from traditional soybean production due to the intensified focus on quality rather than quantity alone. Research emphasizing agronomic practices that improve yield while maintaining high quality is needed for these varieties. Field experiments were conducted in 2018 and 2019 at East Lansing, MI (76-cm row spacing) and Saginaw, MI (38-cm row spacing) to identify optimal planting densities for food-grade soybean varieties. Varieties included a natto-type, tofu-type, two high oleic-type varieties (GMO and conventional), a conventional variety, and a GMO commercial check. Each variety was planted at six densities ranging from 123,500 – 741,000 seeds ha-1. Data collection included plant populations at beginning and end of season, insect pressure, final yield, moisture, test weight and various quality parameters including oil, protein, fatty acid profile, and seed size and uniformity. Varietal response to change in planting density was variable and dependent on location. Yield of both high oleic-type varieties was not impacted by planting density at either location. However, yield of the commercial check and conventional variety consistently increased at both locations as planting density was increased. Oil and protein content was not impacted by changes in planting density at either location for any variety other than the conventional variety where oil content was increased at both locations when a lower planting density (123,500 or 247,000 seeds ha-1) was used and decreased when a higher planting density (618,000 or 741,000 seeds ha-1) was used. Results from this study indicate that changes in planting density may have limited yield and quality benefits.


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