Wheat School: How planting date impacts winter wheat physiology and performance

University of Guelph graduate student Emma Dieleman

Growers who plant winter wheat early can expect higher yields, but growing conditions and the environment can impact plant physiology and how the growing crop should be managed.

On this episode of the RealAgriculture Wheat School, we’re joined by University of Guelph graduate student Emma Dieleman who shares what she’s learning from her planting date research. In the video, Dieleman and host Bernard Tobin start the conversation with a look at her findings on soybean desiccation and the impact on wheat planting date.

Dieleman’s research focuses on three different soybean desiccant products and three application timings. Desiccants sprayed at the earliest application timing (R 6.5) delivered a five to 10 day accelerated soybean drydown. That’s a significant advantage for growers who want to plant wheat as early as possible following soybean harvest, she notes.

When it comes to planting date,┬áDieleman’s research indicates that planting early does deliver a yield advantage. After two years of trials comparing four different planting dates ranging from Sept. 18 to Nov. 15, the data indicates that the earliest planting dates consistently delivers higher yields, she says. As planting dates push later into October and November, yield reductions can range from 10 to 50 bu/ac. (Story continues after the video.)

Dieleman has also noted significant plant physiological differences based on planting date: earlier-planted wheat grows taller, produces more biomass and produces more grain heads per metre. She says one of the key takeaways from her work is the need for growers to pay close attention to environmental conditions and how the crop is growing and developing.

In her research, Dieleman also compared how the wheat crop responds to both standard and intensive management practices. In these trials, the intensive management included a higher nitrogen rate, a second fungicide application, and a plant growth regulator.

In 2021, Dieleman notes that the Ontario crop experienced a significant amount of lodging. In her plots, she observed that yield responses to the standard and intensive management packages were inconsistent. However, lodging was reduced in plots that were intensively managed.

Based on her research, when it comes to winter wheat, she says management decisions really need to incorporate field location/region, growing conditions for that year and planting date.

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