Planting date and seeding rate of field pea in the semi-arid high plains of Nebraska

Results from initial experiments in western Nebraska suggest that opportunity exists to decrease seeding rates of pea (Pisum sativum L.) to optimize yield while maintaining partial net return. Refined planting recommendations, especially planting time, are still largely unknown for western Nebraska. This experiment evaluated the effects of seeding rates and planting dates of pea on emergence, grain yield, and grain yield components. Two locations in Nebraska were evaluated in 2018 and 2019. Treatments consisted of three planting dates and five seeding rates arranged as a split-plot design. Emergence was measured in each plot until emergence stabilized. Whole plant biomass, pods plant^–1, seeds plant^–1, and harvest index were recorded at harvest. Planting later resulted in increased plant density and decreased time to 50 and 90% emergence. Planting date also changed the economically optimal plant population. At Sidney in 2018, optimal plant population changed from 96 plants m^–2 (early) and 115 plants m^–2 (late) to 82 plants m^–2 (middle). Partial net return was increased by US$26.74 ha^–1 and US$65.43 ha^–1 with the middle planting date over the early and late planting dates. Across three site-years, the economically optimal plant population only varied by 4 plants m^–2 between the three planting dates. Later planting improves percent emergence without reducing yield. Seeding rates that have been adjusted for expected germination should target a population between 70 and 109 plants m^–2 to optimize partial net return. Final plant population influences grain yield more than planting date, although both affect yield response.