Maturity Group, Seeding Date, and Location Influence on Soybean Yield.

Higher yield potential is often associated with later maturity cultivars, but growing season shortness and fall frost potential in northern temperate regions often tempers maturity selection to shorter season cultivars. Identification of later maturity group cultivars that reach maturity when grown at different locations and seeding dates could provide potentially higher yields and greater profits to producers. A study was designed to evaluate the influence of location (north/south), seeding date, and maturity group on soybean performance in eastern North Dakota. An RCBD 3x6 factorial experiment with four replicates was conducted at Carrington (northern), Prosper (central), and Lisbon (southern), ND, during the 2014 season. Cultivars from three maturity groups 00, 0, and 1 were AG00932, P90Y70, and P91Y41, respectively, and all glyphosate resistant. Six seeding dates spaced at 7 to 10 d intervals from May 22 to July 10 were sown at each location. Traits evaluated included stand rating, flowering (R1) and maturity (R7), plant height, plant lodging, seed weight, and seed yield. The seeding date by cultivar maturity group interaction was significant for seed yield, R1, R7, and vegetative and reproductive duration at each location. The duration of vegetative development, days from planting to R1, decreased as planting date was delayed for each cultivar at each location. The duration of reproductive development, days from R1 to R7 decreased for the maturity group 0 and 1 cultivars at each location as planting date was delayed, but remained the same for the maturity group 00 cultivar. Seed yield also decreased as planting date was delayed for each cultivar at each location with greater and earlier yield decreases for the maturity group 1 cultivar. Cultivar yield was greater than 1680 kg/ha from the first four seeding dates at Carrington and Prosper except for the maturity group 1 cultivar (1142 kg/ha) at Carrington. At the southern Lisbon location yield was greater than 1680 kg/ha from a July 9 seeding date for the maturity group 00 and 0 cultivars and 591 kg/ha for the maturity group 1 cultivar. Cultivar yield reductions as seeding date was delayed are associated with reduced vegetative and reproductive duration for maturity group 0 and 1 cultivars. Although duration of vegetative development was also reduced for the maturity group 00 cultivar, duration of reproductive development remained constant and benefited yield at later seeding dates.