Soybean Yield and Biomass Responses to Increasing Plant Population Among Diverse Maturity Groups
- Jeffrey T. Edwardsa and
- Larry C. Purcell *b
Soybean [Glycine max (L.) Merr.] production systems that require less than 100 d from sowing to maturity are useful for avoiding drought and decreasing irrigation requirement in areas with relatively long growing seasons (>150 d) and seasonal moisture limitations. Previous experiments have evaluated the response of either maturity group (MG) IV and earlier or MG V and later soybean to increased plant population, but there is a paucity of data quantifying population density responses across the entire range of MGs grown in these areas. Therefore, we evaluated the responses of MG 00, 0, I, II, III, IV, V, and VI soybean to populations of 10, 20, 40, 60, and 100 seeds m−2 sown in 19-cm rows and irrigated as needed at Fayetteville, AR, in 2001, 2002, and 2003. The response of soybean yield to increased plant populations was described well by an exponential model that predicted an asymptotic yield plateau at high plant populations. Asymptotic yield was similar for MG I through VI cultivars, but plant population required to reach the asymptote generally decreased as soybean maturity lengthened. Harvest index (HI) values generally increased slightly with increased plant population in MG 00 and 0 soybean, decreased slightly with increasing plant populations in MG V and VI soybean, and had no response to increasing plant populations in MG I through IV soybean. Height of first fertile node increased as plant population increased and as soybean maturity lengthened. This research demonstrates that a broad range of soybean MGs can produce similar yield in the Midsouth, but optimal seeding densities and irrigation requirements vary by maturity. Further, this research demonstrates some of the difficulties that can be encountered when expressing soybean yield as an empirical function of soybean population density.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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