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Rotational effects and optimized plant spatial arrangement for wheat production in Manitoba

Crop Types
  • Whole Farm
Collaborating Locations


Using and RCBD experiment, the effects of preceding stubble (canola or soybean), row spacing (3.75”, 7.5” and 15”) and seeding density (200, 300, 400, 500seeds m-2) were investigated in two wheat varieties (Cardale and AAC Brandon) in 9 environments over 5 years. This experiment showed that spring wheat growers in Manitoba have the opportunity to increase seed yields by seeding at narrower row spacings. Furthermore, the study demonstrated wheat performs well in either 3 year (wheat - canola- soy) or 4 year (wheat - canola- wheat - soy) rotations. Integrated weed management practices (reduced row spacing and 50% greater seed density) increased yield and reduced weed biomass.


  1. Determine the effect of including 1 vs. 2 wheat crops in rotation with canola and soybean
  2. Determine optimum plant density and row spacing combination for modern wheat varieties, and does the preceding crop affect this.


Overall, narrower row spacing improved wheat yields while seeding density had relatively little effect on yield under weed-free conditions. In a rotation where herbicide-resistant weeds were present, however narrower row spacing and increased seeding densities in all crops had a positive effect on yield and weed suppression. It is important to note that these results should be applied with caution as all years and locations during this research received only 43 to 75 per cent of normal precipitation during the growing seasons.

Key Takeaways

  • Under weed free conditions narrow row spacing (<15") increased wheat yield, while there was no effect of increased seed density.
  • In rotations with group 1 herbicide resistant weeds, narrow row spacing and increasing seed densities improved yield and weed suppression
  • Important to note that the 3 years of study received only 43-75% of normal precipitation

Project Details

Principal Investigator
Dr. Rob Gulden
Project Status
Start Date
Completion Date
Funding Partners
Total Project Cost
MCA Funding

Field Issues

  • Crop Rotation,
  • Seeding