Introduction

AAC Westlock is a hard red spring wheat (Triticum aestivum L.) cultivar developed by the Agriculture and Agri-Food Canada (AAFC), Lethbridge Research and Development Centre (LeRDC), Lethbridge, AB. It was granted registration number 9479 by the Variety Registration Office, Plant Production Division, Canadian Food Inspection Agency, Ottawa, ON, on 3 December 2021. AAC Westlock is adapted to western Canada and meets the quality specifications of the Canada Prairie Spring Red (CPSR) wheat market class. Plant Breeders’ Rights Application No. 21-10 726 was accepted for filing on 21 October 2021.

Pedigree and breeding methodology

AAC Westlock was developed from the three-way cross AAC Foray/AAC Tenacious//AAC Penhold made at the AAFC-LeRDC in Lethbridge, Alberta in 2014. The primary objective of this cross was to develop a high-yielding CPSR wheat cultivar adapted to western Canada with resistance to Fusarium head blight (FHB) and rust diseases. AAC Foray is a high-yielding hard red spring wheat cultivar derived from the cross CPS03hnF45123.032/5701PR developed by the AAFC-Cereal Research Centre (CRC), Winnipeg, Manitoba and registered in 2014 (Brown et al. 2015a). AAC Tenacious is a Fusarium-resistant hard red spring wheat cultivar derived from the cross HY665/BW346, also developed by the AAFC-CRC, Winnipeg, Manitoba and registered in 2014 (Brown et al. 2015b). AAC Penhold, a semidwarf hard red spring wheat cultivar derived from the cross 5700PR/HY644-BE//HY469 was developed by AAFC Swift Current Research and Development Centre, Swift Current, SK and registered in 2014 (Cuthbert et al. 2018).

During the summer of 2015, a total of 461 F₁-derived doubled haploids (DH) were produced using maize hybridization techniques (Sadasivaiah et al. 1999). These DH lines were grown as 1 m rows in a contraseason nursery at Leeston, New Zealand in 2015–2016. Following selection for plant type, height, maturity, and leaf rust resistance, 169 rows were harvested and evaluated in single-replicate yield trials at Lethbridge, Melfort, Kernen, and Portage. These lines were also screened in disease nurseries for leaf rust (caused by Puccinia triticina Eriks. = P. recondita Roberge ex Desmaz.), stem rust (caused by Puccinia graminis Pers.: Pers. f. sp. tritici Eriks. & e. Henn.), stripe rust (caused by Puccinia striiformis Westend. f. sp. tritici Erikss.) common bunt (caused by Tilletia tritici (Bjerk.) G.Wint. in Rabenh. and T. laevis Kühn in Rabenh.) and FHB (caused by Fusarium graminearum Schwabe (teleomorph Gibberella zeae (Schwein.) Petch)) in 2016. After eliminating lines based on agronomic and disease resistance traits, selected lines were analyzed for end-use quality (grain protein, test weight, flour yield, flour ash, kernel hardness, sedimentation volume, falling number, and mixograph parameters). A total of 22 selected lines were tested in replicated B level trials grown over seven locations in Alberta, Saskatchewan, and Manitoba in 2017. These lines were also evaluated for resistance to leaf rust, stem rust (including Ug99 in Kenya), stripe rust, common bunt, and FHB in various disease nurseries. Based on agronomic, disease, and quality testing, one line (WB25597) was advanced to the 2018 High Yield Wheat Registration Trial and evaluated as HY2090 for 3 years (2018–2020).

The registration trials were grown at 15 locations across four zones in western Canada. The criteria for evaluation included grain yield, maturity, plant height, resistance to lodging, resistance to economically important diseases, and end-use quality characteristics. Three CPSR wheat cultivars (AAC Foray, AAC Penhold, CDC Terrain) along with one Canada Western Red Spring wheat cultivar (Carberry) were used as checks.

To assess for disease and insect resistance, artificially inoculated field nurseries were used to determine reactions to leaf rust and stem rust at AAFC-MRDC (Morden, MB) using the modified Cobb scale (Peterson et al. 1948). Seedling reactions were determined in the greenhouse for leaf rust races MBDS (12-3), MGBJ (74-2), TJBJ (77-2), TDBG (06-1-1), and MBRJ (128-1) (McCallum et al. 2020) and to stem rust races TMRTK (C10), RKQSR (C63), TPMKR (C53) RTHJT (C57), QTHST (C25), and RHTSK (C20) (Fetch et al. 2020a, 2020b; Roelfs and Martens 1988). Severity reaction to stripe rust was recorded based on natural field infection in stripe rust nurseries near Lethbridge, AB (Randhawa et al. 2012). Fusarium head blight tolerance was evaluated at Morden and Carman, MB in mist-irrigated field nurseries spray inoculated with a macroconidial suspension and rated using a visual index (% incidence × % severity/100) as described by Gilbert and Woods (2006). Deoxynivalenol (DON) analysis was conducted on composite samples collected from respective FHB nurseries as described by Sinha et al. (1995). Evaluation of common bunt resistance was conducted at the AAFC-LeRDC using a composite of races L1, L16, T1, T6, T13, and T19, and planting into cold soil (Gaudet and Puchalski 1989; Gaudet et al. 1993). For the assessment of orange wheat blossom midge (Sitodiplosis mosellana Géhin) resistance, 10 spikes from each replicate of the agronomic trial were collected at Brandon, MB (a site known for heavy midge pressure) after maturity. Each spike was assessed and rated as either resistant, susceptible, or undamaged.

End-use quality was evaluated by the Grain Research Laboratory (GRL), Canadian Grain Commission (CGC) in Winnipeg, MB, relative to quality checks AAC Foray, AAC Penhold, and CDC Terrain. Composite samples for each test entry were prepared from selected sites based on the protein concentration and grade of the check cultivars. Grain from locations where the checks produced a poor sample was not included in the quality composites. All end-use suitability analyses were performed following protocols of the American Association of Cereal Chemists (AACC 2000).

Analyses of variance were conducted on data from the registration tests using a combined mixed-effects model for agronomic data with years, environments, and their interactions treated as random effects and cultivar treated as a fixed effect. The least significant difference (LSD_0.05 Type I) generated from the analysis of variance was used to identify significant differences of the means of AAC Westlock from those of the check cultivars.

Performance and adaptation

Based on 40 station-years of data in the registration trials from 2018 to 2020, the yield of AAC Westlock was significantly higher than AAC Penhold but similar to AAC Foray in western Canada (Table 1). Overall, AAC Westlock yielded (5697 kg ha⁻¹), about 7% higher than AAC Penhold (P ≤ 0.05). In 2 years of testing (2019, 2020), AAC Westlock yielded about 6% higher than AAC Penhold (P ≤ 0.05). AAC Westlock was 1 day later maturing (P ≤ 0.05) than AAC Penhold but similar to AAC Foray. Plant height was significantly shorter than AAC Foray (P ≤ 0.05). Lodging resistance was similar (P > 0.05) to both AAC Foray and AAC Penhold (Table 2). AAC Westlock had similar test weight and protein concentration but lower thousand kernel weight as compared to AAC Foray (Table 3).

Table 1.

Grain yield (kg ha⁻¹) of AAC Westlock as compared with the check cultivars in the High Yield Wheat Registration Trial (2018–2020).

Table 2.

Agronomic performance of AAC Westlock as compared with the check cultivars in the High Yield Wheat Registration Trial (2018–2020).

Table 3.

Grain characteristics of AAC Westlock as compared with the check cultivars in the High Yield Wheat Registration Trial (2018–2020).

AAC Westlock was resistant to the predominant races of leaf, stem, and stripe rust and common bunt present in western Canada (Table 4). AAC Westlock expressed improved resistance to FHB, with moderately resistant reactions as compared with the check cultivars (Table 4 and Fig. 1).Over years of testing (2017–2021, except for 2019) against the variants of Ug99 in the international stem rust screening nursery in Kenya, AAC Westlock expressed immune reactions as compared with the check cultivars (Table 5).AAC Westlock expressed susceptibility to the orange wheat blossom midge (Table 6).

Table 4.

Reaction of AAC Westlock to various diseases as compared with the check cultivars in the High Yield Wheat Registration Trial (2018–2020).

Fig. 1.

Biplot showing relative position of AAC Westlock as compared to check cultivars using standardized disease index values of 9 Fusarium head blight visual rating index scores and 8 DON values (data source: Table 4).

Table 5.

Disease reactions of AAC Westlock as compared with the check cultivars in the Ug99^a nursery in Kenya during 2017–2021.

Table 6.

Wheat Midge Reaction of AAC Westlock and check cultivars based on data from the High Yield Wheat Registration Trial (2018–2020).AUTHOR: Why are the values in the "AAC Westlock" row in bold?

Three years of end-use suitability testing at the CGC-GRL allowed the Quality Evaluation Team to establish that AAC Westlock had milling and baking quality suitable for grades of the CPSR wheat class (Table 7). The protein concentration of AAC Westlock (12.7%) was lower than the mean of the checks. It had lower Hagberg falling number and higher amylograph peak viscosity (753 BU) over the mean of the checks. It had improved flour yield (77.7% at 0.5% ash) as compared with 76.8% of the mean of the checks. Extensograph area and R_max value indicated that AAC Westlock had stronger rheological properties as compared to the CPSR check cultivars. All other quality parameters and baking properties were similar to the checks (Table 7).

Table 7.

End-use quality characteristics of AAC Westlock and check cultivars with mean data from the High Yield Wheat Registration Trial (2018–2020).

Maintenance and distribution of pedigreed seed

Breeder seed of AAC Westlock was produced by collecting random spikes from a rogued seed increase plot grown at Lethbridge in 2019. One hundred fourteen single head isolation rows were seeded in Lethbridge during 2020. These were observed for uniformity within and among rows, and off-type rows were discarded. Seed from each of the selected 74 progeny rows were seeded at Indian Head in spring 2021. Following the elimination of off-types, the remaining breeder lines were inspected by the Canadian Food Inspection Agency in cooperation with the Canadian Seed Growers’ Association. These lines were harvested as a bulk to constitute the initial breeder seed. The breeder seed of AAC Westlock will be maintained by the AAFC Seed Increase Unit, Indian Head, SK S0G 2K0, Canada following the CGSA Breeder Seed Production Guidelines. Multiplication and distribution of all other pedigreed seed classes will be handled by SeCan, 400-300 Terry Fox Dr, Ottawa, ON K2K 0E3, Canada ( www.secan.com).