Introduction

AAC Oravena is a white-hulled oat (Avena sativa L.) cultivar developed under organic management by Agriculture and Agri-Food Canada, Cereal Research Centre (AAFC–CRC), Winnipeg, MB in collaboration with the University of Manitoba, Winnipeg, MB. AAC Oravena was supported for registration at the Prairie Grain Development Committee Meeting in February 2013. It was registered (Reg. No. 7561) by the Variety Registration Office, Canada Food Inspection Agency on 3 July, 2014. AAC Oravena exhibits good yielding capacity and agronomic performance under organic management systems in the oat producing areas of western Canada. AAC Oravena is the first cultivar to be registered in Canada carrying the oat crown rust (Puccinia coronata Cda f. sp. avenae Eriks.) resistance gene Pc96. AAC Oravena was named by combining ‘organic’ with ‘Avena’.

Pedigree and Breeding Method

AAC Oravena is a white-hulled F₅-derived oat cultivar from a cross made in the fall–winter of 2004–2005 to combine improved yielding capacity with oat crown rust and stem rust (Puccinia graminis Pers. f. sp. avenae Eriks. and E. Henn.) resistance. The cross was made between two breeding lines, 04P01 and 99P26-BY1D. The line 04P01 was an F₁ from the cross of AC Morgan/01RAT23 (Kibite and Menzies 2001), with the breeding line designated as 01RAT23 resulting from the cross of Pinnacle/Pc96 (Mitchell Fetch et al 2003). The crown rust Pc96 single gene differential line is a selection derived from an Avena sativa accession from the Italian Gene Bank, Bari, Italy (Chong and Brown 1996). The paternal parent in the cross was 99P26-BY1D, which resulted from the 3-way cross of Riel/ND931475//HiFi (McKenzie et al 1986; McMullen et al 2005), in which HiFi has Pc91. 99P26-BY1D carried resistance to oat crown rust, oat stem rust, and loose smut (Ustilago avenae (Pers.) Rostr). Thirteen F₁ plants resulting from the final cross were grown in the greenhouse during the winter to the spring of 2005. Seven panicles were selected randomly from these plants, threshed individually, and the F₂ seed was planted in 3.4 m (11 feet) long panicle rows in the 2005 Organic Nursery grown under organically managed conditions on land at the University of Manitoba, Glenlea (UMG), MB. Lines grown at this location were exposed to natural disease infections of oat crown rust, oat stem rust, and barley yellow dwarf virus (BYDV), as well as competitive pressure from various weeds. The diseases may have blown westward across the highway from artificially inoculated AAFC plots. Rows were harvested individually at maturity and seed was sieved to obtain the plumpest seed. The plump F₃ seed was used to plant two 3.4 m (11 feet) long rows in the 2006 Organic Nursery, under organic management at the UMG site. The F₄ seed harvested from each of these rows was again sieved to produce the plumpest seed. This seed was utilized in spring of 2007 to plant two 12-row 2 m × 6 m ‘drill strip’ plots on the UMG organically managed land. The seed produced from these two plots was bulked and sieved to obtain the plumpest filled seeds for planting a single F₅ plot in 2008, again on the organically managed land at the UMG site. Approximately 50 panicles were collected from mature, disease resistant, non-lodged plants within this plot. F₆ seed from 42 selected panicles was sent for increase in two multi-seeded hills in the winter nursery of 2008–2009 near Palmerston North, New Zealand, under conventional management. Ten of these F₅-derived F₆ panicle plots were selected based on lodging resistance, acceptable height, crown and stem rust resistance, tolerance to BYDV, and plots producing ≥130 g of seed. Five of the highest yielding lines were selected for inclusion in the 2009 Preliminary Organic Yield trial, grown at two organically managed locations (University of Manitoba site at Glenlea and at Carman, MB) and one conventionally managed site (Portage la Prairie, MB), plus three artificially inoculated disease nurseries. Disease reaction nurseries were conducted on conventionally managed land, grown as hill plots at the University of Manitoba Point land in Winnipeg, Manitoba. These hill plots were artificially inoculated prior to planting with loose smut, and inoculated in early growth stages with oat crown rust and oat stem rust in separate nurseries. Each year, the crown rust inoculum was a composite of all the races collected from the annual survey in the previous year. For oat stem rust, an epidemic mixture of races FDJ, NGB, TDD, TGB, TGL, and TJJ (corresponding to North American stem rust races NA8, 16, 25, 27, 28, and 67, respectively; Fetch and Jin 2007) increased in a greenhouse was used. As well, a BYDV nursery was grown under conventional management at AAFC–CRC Glenlea, MB where virulent Rhopalosiphum padi (oat bird-cherry aphid) non-specific isolate Y9301 (PAV-like) was used to infect the young plants. Selections were made amongst the lines in the preliminary yield trial and compared with the check cultivars based on superior yield, disease resistance, and milling quality traits as measured by near infrared reflectance (NIR) spectroscopy on whole meal. Three lines performed well in this trial, and were entered into the 2010 B Organic Trial (BORG), grown at four locations across western Canada under organic management (University of Manitoba, Glenlea and Carman, MB; University of Manitoba, Oxbow, SK; University of Alberta West 240 site, Edmonton, AB) and at two conventionally managed sites (Portage la Prairie, MB and Lacombe, AB), as well as in artificially inoculated disease nurseries as described above. Once again, selections were made based on superior performance for the combination of agronomic, disease resistance, and quality traits. One selection, 05P15-OA06, from this trial was entered into the 2011 Western Cooperative Oat Registration Trial (WCORT) as OT8003, and planted under conventional management at 16 sites across western Canada. OT8003 performed well enough in this trial to be entered for a second year of testing in the 2012 WCORT.

Agronomic yield trials also were conducted under organically managed systems, or with no added nutrients or pesticides, at nine locations in the 2012 BORG (Carman, Notre Dame, and Roblin, MB; Kernen and Swift Current, SK; Edmonton, Lamont, and Fort Vermilion, AB; Dawson Creek, BC). Seedling reactions to specific races of oat crown rust and oat stem rust were also evaluated in greenhouses at Winnipeg, MB concurrent to the BORG and WCORT. Means separation and LSD were calculated utilizing the SAS PROC Mixed Macro (Saxton 1998).

One hundred eighty panicles were selected at random from a rogued F₈ increase plot grown at AAFC–CRC, Glenlea, MB, under conventional management in 2010. Seed threshed from each single panicle was planted in plots of paired 1-m rows in isolation near Glenlea, MB in 2011, under conventional management. One hundred seventy-four uniform lines were selected to provide seed for 15-m-long rows produced at Indian Head, SK in 2013. Of these, 151 rows were selected based on uniformity and the seed produced was bulked to form the breeder seed for AAC Oravena.

Performance

Area of adaptation

Based on agronomic and disease resistance testing, AAC Oravena is suitable for organic production systems in western Canada. Across the two years of testing (2010 and 2012), there was no significant difference in yield from the checks in the Black and Brown soil zones (zones 1 and 3) (Table 1). AAC Oravena yielded more than Leggett and CDC Dancer in the Black and Grey soil zone (zone 2), and better than Leggett and AC Morgan in the Brown soil zone. (Table 1). Under organic conditions across western Canada in 2012, AAC Oravena had 3.5% higher yield than Leggett, and out-yielded the high-yielding AC Morgan check at 4 of 9 organically managed sites (data not presented). AAC Oravena headed significantly earlier than AC Morgan and Leggett, and had earlier maturity than all of the checks, but the difference was not significant from the maturity of CDC Dancer (Table 2). AAC Oravena was significantly taller than the checks, but had superior lodging resistance to AC Morgan. AAC Oravena had the highest test weight of all of the organically tested lines, and was significantly higher than AC Morgan. The thousand kernel weight of AAC Oravena was significantly higher than CDC Dancer and AC Morgan. In 2010, AAC Oravena had higher betaglucan (BG) than all of the checks, and had protein, oil and hull content similar to Leggett (Table 3). In 2012, AAC Oravena had higher BG than the checks, with protein content lower and oil content higher than Leggett, but similar hull content (Table 3).

Table 1.

Grain yield (kg·ha⁻¹) of AAC Oravena (OT8003) and check cultivars in the ‘B’ Organic Test (BORG) for 2010 and 2012 in western Canada by soil zones.

Table 2.

Summary of agronomic data for AAC Oravena (OT8003) and check cultivars in the ‘B’ Organic Test (BORG) for 2010 and 2012 in western Canada.

Table 3.

Summary of nutritional quality data^a for AAC Oravena (OT8003) and check cultivars in the ‘B’ Organic Test (BORG) for 2010 and 2012 in western Canada, organically and conventionally managed sites.

Under conventional management systems in 2011 and 2012, AAC Oravena was not significantly different from AC Morgan in yield, except in the Black and Grey soil zone (zone 2) and at the irrigated site near Lethbridge, AB (zone 4) (Table 4). AAC Oravena headed significantly earlier than CDC Dancer, but later than Leggett (Table 5). AAC Oravena matured significantly earlier than AC Morgan and Leggett. AAC Oravena had significantly higher thousand kernel weight and higher total dietary fibre (TDF) than the checks. AAC Oravena had significantly higher betaglucan (BG) and percent protein than CDC Dancer and AC Morgan. The oil content of AAC Oravena was significantly higher than that of the checks (Table 5).

Table 4.

Grain yield (kg·ha⁻¹) of AAC Oravena (OT8003) and check cultivars in the Western Cooperative Oat Registration Test 2011–2012 in western Canada by soil zones.

Table 5.

Summary of agronomic and quality data for AAC Oravena (OT8003) and check cultivars in the Western Cooperative Oat Registration Test in western Canada 2011–2012.

Disease reaction

AAC Oravena is resistant to loose smut, and had slightly better resistance to BYDV than the checks. Crown rust infection was sporadic and spotty in the nurseries the final three years of testing for AAC Oravena. In the 2010 and 2012 BORG tests, AAC Oravena was resistant (0 or R reaction), while the AC Morgan susceptible check had field crown rust reactions of 20S-30S and 20MSS, respectively (data not presented). In the 2011 and 2012 WCORT tests, the crown rust infection was again light and AC Morgan had low levels (2MS or 2S), so it was not useful as a susceptible check (Table 6). Additional data for AAC Oravena in other tests under higher crown rust pressure showed it does possess effective resistance (Table 7).

Table 6.

Summary of disease reactions for AAC Oravena (OT8003) and check cultivars in the Western Cooperative Oat Registration Test 2011–2012.

Table 7.

Summary of oat crown rust severities in field nurseries over years.

Based on the parentage, genes Pc96 or Pc91 (from HiFi) or genes Pc38, Pc39, or Pc68 (from AC Pinnacle) could be present in AAC Oravena. In seedling tests, AAC Oravena was resistant to all crown rust isolates, including CR259 (Table 6). CR259 (LQCB-91) is virulent to Pc38, Pc39 and Pc91, and avirulent to Pc96. Therefore, the resistance expressed by AAC Oravena to CR259 is probably conditioned by Pc96. However, Pc91 could still be present in AAC Oravena, but not detected, because its susceptible reaction to CR259 would be masked by the epistatic effect of the resistance reaction of Pc96. Further tests on AAC Oravena with isolates avirulent and virulent to Pc91 and Pc96 would provide a more definitive answer.

AAC Oravena is thus the first oat cultivar to carry Pc96 registered in Canada. This gene remains effective to the prevalent races in the prairie population since it was first tested in 1996 (Chong and Brown 1996). The resistance gene Pc91 was highly effective until 2011, after which a shift occurred in the crown rust pathogen population, with virulence to Pc91. By 2015, over 67% of the isolates in the rust population were virulent to this gene (Menzies et al. 2019). The susceptible reaction of HiFi and Pc91 in the nurseries in 2019 (Table 7) was a result of this virulence shift. In contrast, the level of resistance for AAC Oravena and Pc96 remained unchanged from that of previous years (Table 7), further supporting the conclusion that Pc96 is present in AAC Oravena and it is this gene that is providing protection.

AAC Oravena had an intermediate reaction to oat stem rust in field inoculated nurseries, and a resistant seedling reaction to specific pathotypes including TJJ (NA67). AAC Oravena may carry novel resistance to TJJ, as in three years of seedling testing, the infection type (IT) was 12- (Tables 6 and 7). Based upon data obtained in 2011 and again in 2018, AAC Oravena has resistance to Fusarium head blight, through lower accumulation of Deoxynivalenol (DON), similar to Leggett (data not shown).

Other Characteristics

Maintenance and Distribution of Pedigreed Seed Stocks

Breeder seed of AAC Oravena will be maintained by the Seed Increase Unit, Agriculture and Agri-Food Canada, Research Farm, Indian Head, Saskatchewan, Canada, S0G 2K0. Multiplication and distribution of pedigreed seed will be through Grain Millers Inc., 1 Grain Millers Drive, Yorkton, SK S3N 3Z4.