Maximizing winter wheat yield through planting date and seeding rate management

Planting date and seeding rate are two of the most basic and important factors in determining yield potential in winter wheat (Triticum aestivum L.) due to their impact on stand establishment. Timely planting of winter wheat (within a few days after the Hessian fly free date) ensures sufficient time for fall growth and tillering, which are critical for maximizing yield, while adequate seeding rate is necessary to optimize the number of heads per unit area. Field experiments were conducted in Mason, MI during three growing seasons (2020-2022) utilizing five planting dates, ranging from mid-September to mid-November, and five seeding rates ranging from 0.8 to 2.4 million seeds acre-1. There was no interaction between planting date and seeding rate in determining yield. Yields declined by 22-48% from the earliest to the latest planting dates in response to a 33-47% reduction in the number of heads acre-1. Seeding rate did not significantly impact yield except at low seeding rates under delayed planting. Maximum yield was achieved with a seeding rate of 0.93, 1.37, 1.47, 1.54, and 1.85 million seeds acre-1 during the mid-September, late September, mid-October, late October, and mid-November plantings, respectively. Overall, results demonstrated that timely planting of wheat is critical for maximizing yield, with significant yield reductions occurring when planting is delayed, regardless of the seeding rate used. Furthermore, while low seeding rates may be used within the optimal planting window without yield penalty, seeding rates should be progressively increased as planting is delayed to diminish yield loss. Optimal planting time is critical for maximizing winter wheat yields.Increasing seeding rate did not make up for yield loss from delayed planting.Optimal seeding rate was lowest within optimal planting window and progressively increased with delayed planting.