Optimizing canola production
For both early- and late-maturing hybrids, straight-cutting canola at 10% seed moisture produced high, stable yields. While seeding at 18 seeds/ft2 produced the highest yield, it also had the lowest net returns due to high seed costs. Seeding at 12 seeds/ft2 provided a balance between yield, seed costs, and net returns.
With the evolution of pod shatter resistant hybrid canola, canola growers have shifted their management practices in an effort to maximize yield and reduce costs. A recent research project investigated how seeding rate, swathing canola, and straight cutting pod shatter resistant canola hybrids impacted seed yield and quality. It also looked at how seeding rate, variety selection, and harvest management impact canola canopy architecture.
The research was conducted between 2018 and 2022 (excluding 2020) at two sites near Lethbridge (irrigated and dryland), and one site at each of Lacombe, AB, Indian Head, SK, and Brandon, MB. Three seeding rates of 6, 12, and 18 seeds/ft2 (60, 120, and 180 seeds/m2) that targeted plant stand densities of 4, 7, and 10 plants/ft2 (40, 70, and 100 plants/m2) were compared. InVigor L233P (early maturing) and InVigor L255PC (late maturing) pod shatter resistant varieties were compared.
Harvest methods compared included windrowing at 60% and 90% seed color change, and straight cutting at 10% and 5% seed moisture. Reglone was applied to the straight cut treatments to achieve uniform dry down and to test pod shattering when harvest was delayed. The 90% seed colour change and 5% seed moisture straight cut treatments simulated a delayed harvest.
The field plots were sown into a cereal or pulse stubble with knife openers on 9 or 12 inch (23 or 30 cm) row spacings. Standard agronomic practices were applied to the plots.
GxExM interactions
The highest yields came from the later maturing L255PC variety compared to the earlier maturing L233P variety. Later maturing varieties typically yield higher as they have a longer growing season to capture more resources to increase yield.
Yield was also highest when the varieties were sown at 12 and 18 seeds/ft2, which resulted in plant stands of 5.7 and 8 plants/ft2 on average. Canola seeded at 6 seeds/ft2 and windrowed yield the lowest. For example, L255PC sown at 6 seeds/ft2 yielded 47 bu/ac (2.66 t/ha) but yielded 51 bu/ac (2.86) when seeded at 12 or 18 seeds/ft2.
Straight cutting canola also resulted in higher yield than windrowing canola.
Data analysis found that yield was greatest for straight cut L255PC when seeded at 12 or 18 seeds/ft2 compared to other treatment combinations. The average yield of L225PC when seeded at 12 or 18 seeds/ft2 and straight cut at 10% seed colour change, or seeded at 18 seeds and straight cut at 5% seed colour was 4.3 bu/ac (0.24t/ha) higher than the other treatment combinations.
The analysis also found that most of the straight cut yields when seeded at 12 or 18 seeds/ft2 had the highest, most stable yielding. For both hybrids, windrowed canola that was seeded at 6 seeds/ft2 had the lowest, most unstable yields. But the research also showed that the lowest seeding density works when environmental stress is low such as under irrigation. However, if there is stress such as drought, flea beetles, and disease, plants cannot compensate enough through changes in yield components like additional branching and podding to maintain yield potential.
These seeding rate yield results are consistent with a meta-analysis conducted in 2020 by Hartman and Jeffrey. They found that “hybrid canola achieved 95% of its yield potential with 6.5 to 8.5 plants/ft2, 90% with 3 to 4.5 plants/ft2, and 85% with 2 to 3 plants/ft2.”
Oil content was lower for L233P at 46.5% compared to L255PC at 48.5%. Straight cut L233P had slightly higher oil content than windrowed, while windrowed L255PC had slightly higher oil content than straight cut.
Canola sown at 6 seeds/ft2 lagged in crop development by up to five days, but developed more branches and pods per plant. Increased intra-plant competition with higher seeding rates meant increased seed yield and seed weight on secondary branches, which were critical yield components.
Economic analysis showed there is a balance between seeding rate, yield, and economic returns. Based on 2023 InVigor seed prices, the additional input cost for seeding at 18 seeds/ft2 would be $126/ac ($311/ha) higher than the 6 seeds/ft2 rate, and $63/ac ($155/ha) higher than the 120 seeds/ft2 rate.
The estimated net return based on 2023 canola prices found that the 18 seeds/ft2 seeding rate was $79/ac ($196/ha) less than the 12 seeds/ft2 rate and $50/ac ($123/ha) less than the 6 seeds/ft2 rate. This would mean that 12 seeds/ft2 found the sweet spot and produced a net return $29 higher than the 6 seeds/ft2 seeding rate and $79/ac more than the highest seeding rate.
Overall, for both early- and late-maturing hybrids, straight-cutting canola at 10% seed moisture produced high, stable yields. While seeding at 18 seeds/ft2 produced the highest yield, it also had the lowest net returns due to high seed costs. Seeding at 12 seeds/ft2 which resulted in an average plant stand of 5.7 plants/ft2 provided a balance between yield, seed costs, and net returns.
The researchers said that “reduced intra-plant competition is essential for secondary branch formation and overall yield development. These findings prompt the question of whether precision planting in canola could help achieve a more spatially uniform stand, thereby improving seedling emergence, canopy uniformity, and ultimately yield with lower seeding densities.”
This research was funded by the Canola Council of Canada, Alberta Canola Producers Commission, Sask Canola, and Manitoba Canola Growers Association, with additional funding leveraged from the Canadian Agricultural Partnership’s AgriScience Program, a federal, provincial, territorial initiative.
Beres, B. L., Wang, Z., Stevenson, F. C., Geddes, C. M., Tidemann, B. D., Kubota, H., May, W. E., & Mohr, R. M. (2025). Optimizing canola production in the Northern Great Plains by leveraging genotype × environment × management synergies. Crop Science, 65, e70115. OPEN ACCESS https://doi.org/10.1002/csc2.70115
