Optimal Agronomics Increase Grain Yield and Grain Yield Stability of Ultra-Early Wheat Seeding Systems

Abstract

Ultra-early seeding of spring wheat (Triticum aestivum L.) on the northern Great Plains can increase grain yield and grain yield stability compared to current spring wheat planting systems. Field trials were conducted in western Canada from 2015 to 2018 to evaluate the impact of optimal agronomic management on grain yield, quality, and stability in ultra-early wheat seeding systems. Four planting times initiated by soil temperature triggers were evaluated. The earliest planting was triggered when soils reached 0–2.5 °C at a 5 cm depth, with the subsequent three plantings completed at 2.5 °C intervals up to soil temperatures of 10 °C. Two spring wheat lines were seeded at each planting date at two seeding depths (2.5 and 5 cm), and two seeding rates (200 and 400 seeds m−2). The greatest grain yield and stability occurred from combinations of the earliest seeding dates, high seeding rate, and shallow seeding depth; wheat line did not influence grain yield. Grain protein content was greater at later seeding dates; however, the greater grain yield at earlier seeding dates resulted in more protein production per unit area. Despite extreme ambient air temperatures below 0 °C after planting, plant survival was not reduced at the earliest seeding dates. Planting wheat as soon as feasible after soil temperatures reach 0 °C, and prior to soils reaching 7.5–10 °C, at an optimal seeding rate and shallow seeding depth increased grain yield and stability compared to current seeding practices. Adopting ultra-early wheat seeding systems on the northern Great Plains will lead to additional grain yield benefits as climate change continues to increase annual average growing season temperatures.

Fall-applied residual herbicides improve broadleaf weed management in ultra-early wheat (Triticum aestivum L.) production systems on the northern Great Plains

“…Using an average wheat grain value of $261.00 Mg -1 (September 2015 to December 2021 average southern Alberta price for CWRS wheat, 13.5% protein content), a grower would expect a gross economic benefit of $117.45 ha -1 by shifting to an ultra-early planting date (Alberta Wheat Commission 2021). Greater grain yield at sites south of 51°N latitude resulting from ultra-early seeding can be attributed to increased plant populations, earlier access to spring soil moisture, drought and heat stress avoidance and a longer vegetative growth period similar to the reports of Kirkegaard et al (2015), Hunt et al (2018), andCollier et al (2021).…”

“…The initial planting date was triggered when soil temperatures first reached 2°C and the second planting date was triggered when soils first reached 8°C. In order to more readily identify any effect of soil-applied residual herbicide activity on spring wheat survival, phytotoxicity and grain yield, the wheat line "LQ1299A", as described in Collier et al (2020Collier et al ( , 2021, was planted at a sub-optimal sowing density of 200 viable seeds m -2 . Previous studies completed by Collier et al (2021) indicated optimal seeding rates increased ultra-early wheat growing system stability and thus, if used in this study, could have served to mask potential negative effects of herbicide applications combined with sub-optimal growing conditions.…”

“…Similar to Collier et al (2021), days to emergence was recorded when an estimated 50% of seedlings had emerged in a plot based on daily visual assessments. Crop anthesis was determined as days from planting date when an estimated 50% of the heads in a plot first extruded anthers based on daily visual assessment.…”

“…The period of time between emergence and maturity was broken into three sub-segments, all reported in days: emergence to anthesis, anthesis to 8 maturity, and emergence to maturity. This is necessary to investigate differential lengths of growth periods between planting dates and herbicide treatments and remove the confounding effect of increased days to emergence often observed with ultra-early planting dates (Collier et al 2020(Collier et al , 2021.…”

“…This result varies from similar studies conducted by Collier et al (2020), who reported similar yields between ultra-early and later planting dates, but an increase in growing system stability when planting occurred ultra-early. Collier et al (2021) reported that using optimal wheat seeding rates of 400 viable seeds m -2 or more increased growing system stability of ultra-early wheat growing systems. The incongruity between studies at sites north of 51°N latitude may be attributed to the sub-optimal seeding rate of 200 viable seeds m -2 used in this study versus the seeding rate of 400 viable seeds m -2 used in the study completed by Collier et al (2020).…”