Ultra-early durum adapted to the Prairies
Planting CWAD wheat at a trigger temperature of 2 C had high and often more stable grain yields than planting at 10 C, with higher economic returns.
Previous research found that ultra-early seeded spring wheat varieties provided improved grain yield stability while protecting or improving grain yield, earlier harvests and improved weed competitiveness. However, research into ultra-early durum wheat production was lacking.
A research trial was conducted from 2022 to 2024 at four locations in Alberta and Saskatchewan to “assess the feasibility of and risks associated with ultra-early seeding of durum wheat into cold soils.” In 2022, the locations were two sites at Lethbridge, Alta., and Indian Head, Saskatoon, and Swift Current, Sask. In 2023 and 2024, an additional irrigated site at Lethbridge was added. The five Canada Western Amber Durum varieties compared were AAC Donlow, CDC Desire, CDC Defy, AAC Stronghold and Transcend.
Plant dates were based on temperature trigger points measured at a two inch (5 cm) depth in the soil at 10 a.m. The first planting occurred at a trigger point of 0 C, followed by five plantings at 2 C intervals at 2, 4, 6, 8 and 10 C.
Seeding equipment varied by site but primarily used low disturbance openers on row spacings of 9.5 to 11.8 inches (24 to 30 cm). Seeding rates were calibrated to 40 seeds per square foot (400/m2) to target a plant stand of 25 to 30 plants/ft2 (250 to 300/m2). A dual fungicide:insecticidal seed treatment was applied to all treatments to buffer against abiotic stress associated with cold soil environments.
Pre-plant herbicide application was not applied because few weeds were present at ultra-early seeding dates. In-crop herbicides were applied as needed.
Higher yields with ultra-early seeding
Despite the concerns that durum wheat has a purported weaker vigour and higher propensity for sprouting than hard red spring wheat, this was not evident in this research trial. Seeding occurred as early as Feb 9 with as many as 69 days of below freezing after planting, and plant establishment and survivability were similar to the 10 C planting date.
Earlier planting dates resulted in longer days to emergence, anthesis, and maturity. However, the opposite occurred with maturity date with the early seeding triggers maturing earlier than the later seeded crops. For example, seeding at the 2 C trigger resulted in an average crop maturity date of August 12 (224 Julian) compared to August 18 (230 Julian) for the 10 C trigger.
Across all environments, the yield responses of the five durum wheat varieties under ultra-early seeding reflected those found in varietal registration trials. CDC Defy, AAC Donlow and AAC Strongfield had similar yields that were higher than CDC Desire and Transcend.
The highest yields across varieties and locations occurred at an ultra-early trigger temperature of 2 C. Similar yields were seen at seeding temperatures of 0, 4, 6 and 8 C, with the lowest yield at 10 C trigger temperature. Yield was 6.6 per cent higher for the 2 C seeding date compared to the 10 C seeding date.
CDC Defy and CDC Desire had the highest yields at the 2 C planting, while AAC Donlow yielded highest at the 4 C planting temperature, and Transcend yielded highest at the 0 and 4 C planting temperatures. AAC Strongfield yielded similarly across all trigger temperatures. All varieties yielded the lowest at the 10 C trigger temperature.
Grain yield response to prescriptive planting time dictated by soil temperature triggers, averaged over all locations in 2022 – 2024 (excludes Indian Head 2022)
Source: Wang et al. 2026
Yield stability analysis found that, overall, yield of all cultivars was most stable at lower trigger temperatures, and that CDC Defy and Transcend appeared particularly well-adapted to colder planting temperatures. The researchers indicated that the downward trend in yield with later planting dates is likely related to abiotic stresses such as heat and drought stresses since the crop flowered and matured later than the earlier planted treatments. Conversely, the critical growth period of ultra-early treatments was shifted into June and out of July, thereby avoiding heat and drought stress typically experienced in prairie environments. Grain protein was not affected by soil temperature trigger seeding dates for any variety.
Higher economic returns
A simple economic analysis was conducted where net return was calculated by multiplying the grain yield by commodity price and subtracting the seed weight times the average price of seed. All other production costs were assumed to be the same across planting dates. Planting at 2 C had significant higher net returns at $54/ac ($134/ha) than at 10 C. CDC Defy had the highest net return of all treatments when seeded at 2 C with AAC Donlow seeded at 4 C as the next highest net return.
An additional economic benefit from ultra-early seeding could be realized from eliminating a pre-plant herbicide application, as was done in this trial. Typically, seeding at a conventional date around 10 C would require a pre-seed herbicide application.
Overall, the research found that planting CWAD wheat at a trigger temperature of 2 C had high and often more stable grain yields than planting at 10 C. While this practice may not be possible on every durum field in every year because of field conditions that may prevent access to seeding, ultra-early durum seeding is a practice that should be considered across the durum growing region of the southern Prairies.
This research was funded by the Saskatchewan Wheat Development Commission.
Wang, Z., Pozniak, C., Ruan, Y., Liu, K., Willenborg, C., May, W., Coles, K., & Beres, B. L. (2026). Is durum wheat amenable to an ultra-early seeding system and associated abiotic stress?. Crop Science, 66, e70234. https://doi.org/10.1002/csc2.70234
