Effects of seeding date on grain and biomass yield of intermediate wheatgrass

Authors: JUNGERS, JACOB - University Of Minnesota; SCHIFFNER, SYDNEY - University Of Minnesota; SHEAFFER, CRAIG - University Of Minnesota; EHLKE, NANCY - University Of Minnesota; DEHAAN, LEE - The Land Institute; TORRION, JESSICA - Montana State University; NOLAND, REAGAN - Texas A&M University; Franco, Jose

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2022
Publication Date: 4/26/2022
Citation: Jungers, J., Schiffner, S., Sheaffer, C., Ehlke, N., DeHaan, L., Torrion, J., Noland, R., Franco Jr, J.G. 2022. Effects of seeding date on grain and biomass yield of intermediate wheatgrass. Agronomy Journal. 114(4):2342-2351. https://doi.org/10.1002/agj2.21083.
DOI: https://doi.org/10.1002/agj2.21083

Interpretive Summary: Kernza intermediate wheatgrass is a perennial grain crop being developed for its environmental and economic benefits. As a perennial, it does not require replanting year after year as annual grain crops, and it can be utilized for grain as well as for forage within the same growing season. Further, Kernza's deep root system can provide multiple soil-associated benefits. However, there is a lack of information on optimal seeding dates for maximized grain and biomass yield across a range of growing environments. To address this knowledge gap, a study was conducted in Minnesota, Kansas, and Montana (and Texas and Arkansas, though lack of successful establishment prohibited sufficient data collection at these sites) whereby Kernza was planted at various late summer, fall, and spring dates. In northern cropping systems such as in Minnesota and Montana, seeding between mid-August to early-September resulted in the greatest yields. In Kansas, a wider range of seeding dates in September and October resulted in the greatest yields. These results contribute to our understanding of how Kernza will perform in various growing environments and which crops it can most successfully follow in a crop rotation. This information is critical for producers in different regions of the US interested in growing Kernza to diversify their crop rotations and reap the environmental and economic benefits of integrating this perennial grain crop on their farms.

Technical Abstract: Intermediate wheatgrass (Thinopyrum intermedium, IWG) is a perennial grain crop being developed to provide economic return as well as ecosystem services. IWG is a new crop with the potential for a broad geographic range of production in North America, yet optimum seeding dates for establishment are unknown. Our objective was to determine the effect of late-summer, fall, and spring seeding dates on seed and biomass yield of an IWG population developed for grain production. Data were collected from trials at St. Paul and Roseau, MN, Kalispell, MT, and Salina, KS. Planting dates ranged from mid-August to June. Grain and biomass yields were highest when seeded at the earliest late-summer date for all environments except for Kansas, where a September 29 seeding date resulted in the greatest grain and biomass yields. Little to no harvestable grain was produced from spring seeded stands, substantiating that photoperiod and temperature requirements are needed for flowering and grain production. At Salina, KS, the relationship between growing degree days (GDD) and seed and biomass yields was quadratic suggesting that diminishing returns on yield accrue at a threshold early planting date when 754 and 744 GDD were accumulated prior to a killing frost for seed and biomass yield, respectively. The relationships between GDD and seed and biomass yield were linear at Kalispell, MT, and St. Paul and Roseau, MN, indicating that planting dates earlier than those tested here (15 August -1 September) should be investigated.