AAC Douglas oat

Abstract AAC Douglas is a white-hulled spring oat (Avena sativa L.) cultivar, with superior grain-yield potential in the western Canadian oat production areas, yielding 3.5% higher than Summit. AAC Douglas was registered for commercial production in Canada (Reg. No. 8950) on 21 February 2020. AAC Douglas has high protein (5% higher significantly (P=0.05) than AC Morgan) and beta-glucan content (10.6% higher than the nearest check, Summit), making it attractive for milling purposes. AAC Douglas is resistant to loose smut and covered smut, with moderately resistant to intermediate reactions to other diseases encountered in western Canada.


Pedigree and breeding method
AAC Douglas was developed from the cross of OT7070 with CS Camden, made during the spring of 2011. The intention of this cross was to combine the superior grain-yield potential, early maturity, lodging resistance, and high protein of CS Camden with the higher yield, lower oil, and higher beta-glucan of OT7070 (OT2068/Stainless) (Mitchell Fetch et al. 2011), as well as its good crown-rust resistance. OT7070 was developed through the Organic Oat Breeding program but did not perform well enough to be considered for cultivar registration. OT2068 resulted from the cross between Leggett/01RAT23 (Mitchell Fetch et al. 2007), with 01RAT23 being an improved sib of Pinnacle (Mitchell Fetch et al. 2003), with the addition of the Pc96 crown rust-resistance gene. CS Camden resulted from the cross of SW Betania/Dominik made in Svalöv, Sweden. The F 1 generation resulting from the cross OT7070/CS Camden was labelled as 11P17 and was produced in five single-seed hills near Palmerston North, New Zealand, during the winter of 2011-2012. A bulk of F 2 seeds from each separate F 1 hill was grown in five thinly seeded (∼250 seeds per plot) yield-size plots (3.5 m 2 ) in the Disease Nursery in 2012, grown at the University of Manitoba Point land in Winnipeg, MB. All of the lines in this nursery were artificially inoculated prior to seeding with black loose smut (Ustilago avenae (Pers.) Rostr.) using a mixture of three races, A13, A60, and A617. Resistance to loose smut also confers resistance to covered smut . The plants were artificially inoculated at about the tillering stage with oat crown rust (Puccinia coronata Corda. f. sp. avenae Eriks.) (OCR), using a mixture of predominant races collected in previous years (Chong et al. 2009), and oat stem rust (Puccinia graminis Pers. f. sp. avenae Eriks. and E. Henn.) (OSR), using a mixture of races to test for the presence of specific seedling-resistance genes. Each of these plots was Two hundred fifty panicles were selected from rogued increase plots grown at Lacombe, AB, in 2016. Seeds from individual panicles were threshed and planted as F 9 rows in isolation near Brandon, MB, in 2017. Two hundred fifteen lines that were uniform were planted as F 10 progeny line breeder plots at Indian Head, SK, in 2018. From these rows, 209 were selected for their uniformity and utilized to constitute the approximately 459 kg of breeder seed. The discarded lines were either ragged or taller than the others.

Performance
AAC Douglas yielded similarly to AC Morgan, slightly less but not significantly different in the Black, Black and Grey, and Brown and Dark Brown soil zones. AAC Douglas significantly outyielded CDC Dancer, by 8%-12% higher (P = 0.05) everywhere except in the Brown soil zone (Table 1). AAC Douglas headed significantly earlier than AC Morgan, more than 2 days earlier, and CDC Dancer, almost 1 day earlier (Table 2). It matured significantly later, by 2 days, than CDC Dancer but 1 day earlier than AC Morgan and almost 2 days earlier than Summit, with a long grain-filling period potentially adding to the higher yield. AAC Douglas is taller than Summit but grows shorter than CDC Dancer and AC Morgan. There were no significant differences observed among these lines for lodging resistance during the two years that AAC Douglas was tested in the WCORT. However, where lodging was observed, AAC Douglas had one of the better resistance scores, although the raw data are not presented here. AAC Dancer had significantly lower test weight than the check cultivars but significantly higher thousand kernel weight  Note: Means within a column not sharing a lowercase letter differ significantly at the P < 0.05 level. Means separation and LSD were calculated utilizing the SAS PROC Mixed Macro (Saxton 1998 than CDC Dancer and Summit (Table 2). Percent plump kernels was lower than the check cultivars but not significantly so. Conversely, the groat % for AAC Douglas was not significantly different from the checks, higher than AC Morgan and slightly lower than CDC Dancer and Summit (Table 2). AAC Douglas has significantly higher protein content than CDC Dancer and AC Morgan, at least 5% higher, while its oil content was similar to Summit and under the maximum oil content preferred by domestic oat-milling companies (PRCOB 2021). AAC Douglas has significantly higher betaglucan content than the checks at 5.2%, with higher total dietary fibre than CDC Dancer and AC Morgan, making it attractive for milling-quality oat production (Table 2).

Disease reaction
AAC Douglas is resistant to loose smut and covered smut  but has intermediate to susceptible tolerance to BYDV, based on one season of inoculated evaluation (Table 3). AAC Douglas has moderate resistance to FHB, exhibited by low levels of DON retention in the seed. AAC Douglas had an intermediate field reaction to OSR when it was tested in the 2017-2018 WCORT, and the susceptible seedling reaction to TJJ (NA67) indicates that it does not carry the Pg-a stem rust resistance from the Stainless parent, as was hoped (Table 3). AAC Douglas may carry Pg13 since this is linked to Pc91 (Kebede et al. 2020). During the testing in the WCORT, AAC Douglas had a moderately resistant reaction to OCR in the field, so it likely does not carry the Pc96 resistance gene but only Pc91, based on its parentage and seedling reactions to individual OCR races (Table 3).

Other characteristics
SEEDLING (5-9 tiller stage): spring oat, hulled, erect to semi-erect juvenile growth habit, dense pubescence of lower leaf sheath and medium-dense pubescence of lower leaf blade.
LEAF (at booting stage): medium-dark green, sparse pubescence of margin, weak intensity of glaucosity at green stage, recurved, narrower, shorter flag leaves.
CULM: very dense hairiness of stem above and dense hairiness below upper node. PANICLE (shortly after heading): medium to dense density. PANICLE BRANCHES: equilateral orientation of horizontal branches.
KERNEL (primary kernels from upper spikelets): whitehulled, short basal hairs present, cream, two grains per spikelet, sparse density of pubescence on groat. AAC Douglas has a tendency to produce awned lemmas; however, the trait is not evenly expressed within a plant, with awned and awnless florets occurring on the same plant.

Maintenance and distribution of pedigreed seed stocks
Breeder seed of AAC Douglas will be maintained by the Seed Increase Unit, Agriculture and Agri-Food Canada, Note: BYDV ratings may be higher than usual as stunting could have been attributed to BYDV rather than weather stress. a OCR greenhouse ratings: all entries were inoculated with selected races of crown rust in greenhouse seedling tests. Ratings follow Stakman et al. (1962). b OSR greenhouse ratings: all entries were inoculated with seven selected races of stem rust in greenhouse seedling tests. Ratings follow Stakman et al. (1962). c BYDV data: provided by Dr. Frederic Kolb, University of Illinois, Urbana, IL, USA. Infections caused by natural viruliferous oat bird-cherry aphid (Rhopalosiphum padi). Rating based on field readings, on the average of two replications, mid-dough using 1-9 (best-worst) scale; R = 1-3.5, MR = 3.51-4.5, MR-MS or I = 4.51-5.5, MS = 5.51-6.5, S = 6.51-9.0. d Smut data: a mixture of three races of black loose smut [Ustilago avenae (Pers.) Rostr.], A13, A60, and A617, was used as inoculum. % infection: R = 0%-15%, MR = 16%-35%, MR-MS = 36%-55%, MS = 56%-75%, S > 75%. e FHB data--X. Wang: field data based on a mean of four reps in a nursery inoculated with infested corn spawn. DON data supplied by B. Blackwell. DON ratings were scored as follows: R = <2.1 ppm, MR = 2.1-10.0 ppm, I = 10.1-30.3 ppm, MS = 30.3-42.2 ppm, S ≥ 42.2 ppm. f Oat crown rust: field ratings based on artificial inoculation with a composite of isolates bulked from the previous year annual crown rust survey in MB. Ratings follow Peterson et al. (1948), where 0 represents immune, VR represents very resistant, Tr represents trace, R represents resistant, MR represents moderately resistant, MS represents moderately susceptible, and S represents susceptible. g Oat stem rust: field ratings based on reaction to an artificially inoculated mixture of races (NA8,16,25,27,28,55,and NA67). Ratings follow Peterson et al. (1948) as listed above.