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a Crop and Soil Environmental Sciences Dep., Virginia Polytechnic Inst. and State Univ., Blacksburg, VA 24061
b Eastern Virginia Agricultural Research and Extension Center, Virginia Polytechnic Inst. and State Univ., Warsaw, VA 22572
c USDA-ARS Plant Science Unit, Department of Crop Science, North Carolina State Univ., Raleigh, NC 27695
* Corresponding author (cgriffey{at}vt.edu)
‘Thoroughbred’ (Reg. no. CV-316, PI 634933) is a high-yielding, awned, six-rowed, hulled winter-feed barley (Hordeum vulgare L.) that was developed and released May 2003 by the Virginia Agricultural Experiment Station. Thoroughbred is well-adapted to winter barley production areas across the mid-Atlantic and southeastern regions of the U.S.A. The name Thoroughbred was selected to denote the superior seed quality of this cultivar, which produces exceptionally bright plump kernels in warm humid environments of the East Coast.
Thoroughbred was derived from a cross between VA90-44-110 and ‘Plaisant’ (PI 584894). The pedigree of the female parent VA90-44-110 is CIho 8618/‘Surry’//‘Sussex’/3/‘Henry’, ‘Maury’, VA79-44-167 (Starling et al., 1980a, 1980b, 1980c, 1984). CIho 8618 (PI 178381) is an awned winter barley accession from Turkey that was used as a source of resistance to scald [caused by Rhynchosporium secalis (Oudem.) J.J. Davis]. The parentage of VA79-44-167 is ‘Cebada Capa’ (PI 539113)/‘Wong’//Awnleted ‘Hudson’/3/‘Harrison’/4/Harrison/3/CebadaCapa/Wong//Awnleted Hudson (Jensen, 1964; Caldwell et al., 1966). Plaisant is an awned French winter malting cultivar. The cross from which Thoroughbred originated was made in spring 1991, and the F1 generation was grown in the field as a single 1.2-m headrow in 1992 to produce F2 seed. The population was advanced from the F2 to F4 generation using a modified bulk breeding method. Barley spikes were selected from the population in each segregating generation on the basis of disease resistance, desirable maturity, short straw, and desirable head type and size. Selected spikes were threshed in bulk, and the seed was sown in a 20.9-m2 block in the fall of each year. Spikes selected from the F4 bulk were threshed individually and sown in separate 1.2-m headrows. Thoroughbred was derived from a single F4:5 headrow selected and harvested in bulk in 1996. The line was tested as entry 388 in nonreplicated observation yield tests in 1997 and was designated VA97B-388. In addition to high grain yield, Thoroughbred was selected on the basis of very good straw strength, high test weight, and its exceptionally bright, plump, and superior seed quality.
Juvenile plants of Thoroughbred exhibit a semi-prostrate growth habit in early spring, flag leaves are slightly waxy and upright at booting, leaf sheaths, and stems are waxy, and anthocyanin is not visually apparent in leaves or stems. Stems are comprised of four nodes with moderate exertion between flag leaf and spike, have a closed collar and a slightly undulated neck. Spikes are erect, lax to dense and slightly waxy with no overlapping lateral kernels. The rachis is covered with hairs. Glumes are of medium length with short hairs confined to the band, and their awns are smooth and less than or equal to the glumes in length. Lemmas are hairless, have a depressed base, and their awns are long and rough. Rachilla hairs are long. Seed are hulled, midlong to long, slightly wrinkled, with colorless aleurone, and lacking hairs on the ventral furrow.
On average (22 station years), head emergence of Thoroughbred in Virginia is 2 d later than ‘Wysor’ and 4 d later than ‘Nomini’ (Starling et al., 1987, 1994). Average (19 station years) plant height of Thoroughbred (91 cm) is 8 to 10 cm taller than ‘Callao’ and ‘Price’, and 8 to 10 cm shorter than Wysor and Nomini (Price et al., 1996; Brooks et al., 2005). On the basis of Belgian lodging score (0.2 = no lodging, 10 = completely lodged), average (24 station years) straw strength of Thoroughbred (1.4) is similar to those of Price (1.5) and Nomini (1.7), and better than those of Wysor (2.8) and Callao (5.0). Winter hardiness of Thoroughbred is good and most similar to that of the hardy barley check ‘Kentucky 1’ (CIho 6050). In the 1999 to 2000 USDA-ARS Uniform Barley Winter Hardiness Nursery, Thoroughbred ranked 1st among 29 entries for winter hardiness with a mean survival score of 94%, compared with 81% for ‘Tennessee Winter’ (PI 11193), 85% for Kentucky 1, and 63% for ‘Trebi’ (Wiebe, 1965). In the 2000 to 2001 nursery, average winter survival of Thoroughbred (55%) was similar to that of Tennessee Winter (50%) and Kentucky 1 (59%) and significantly higher than that of Trebi (35%).
On the basis of disease assessments [Infection Type (IT), 0 = immune to 4 = highly susceptible] of seedlings conducted in greenhouse tests from 1999 to 2002, Thoroughbred is resistant (IT = 1) to powdery mildew [caused by Blumeria graminis (DC.) E.O. Speer f. sp. hordei Em. Marchal] but moderately susceptible (IT = 3) to leaf rust (caused by Puccinia hordei G. Otth) race 8 and race 30. In field tests (1999–2002), adult plants of Thoroughbred have expressed resistance (0 = resistant to 9 = susceptible) to powdery mildew (1.3) and Septoria leaf blotch (0.2) (caused by Septoria passerinii Sacc.). Thoroughbred has expressed susceptibility to leaf rust (7.0) and moderate susceptibility to net blotch (4.0) (caused by Pyrenophora teres Drechs.).
Thoroughbred was tested in Virginia's State Variety Trials from 1999 to 2002 (18 station years). Average grain yield of Thoroughbred (6450 kg ha–1) in Virginia has been excellent in comparison with those of Nomini (6343 kg ha–1), Price (6235 kg ha–1), and Callao (5966 kg ha–1). In three out of four years, grain yields of Thoroughbred exceeded those of Nomini by 323 to 753 kg ha–1 and those of Callao by 430 to 968 kg ha–1. In the USDA-ARS Uniform Winter Barley Yield Nursery, average grain yield of Thoroughbred (6128 kg ha–1) over 10 states in 2000 was 538 to 753 kg ha–1 higher than those of Nomini, Price, and Callao, and in 2001 over four states, average yield of Thoroughbred (5913 kg ha–1) was 430 to 484 kg ha–1 higher than those of Nomini and Callao. Over all locations, Thoroughbred ranked 1st among 23 entries in 2000 and 3rd among 23 entries in 2001.
Average (16 station years) test weight of Thoroughbred (659 kg m–3) in Virginia has been similar to those of Callao (663 kg m–3) and Price (655 kg m–3) and significantly (P 
0.05) higher than those of Wysor (629 kg m–3) and Nomini (622 kg m–3). In the 1999 to 2000 USDA-ARS Uniform Winter Barley Yield Nursery, average test weight of Thoroughbred (605 kg m–3) was similar to that of Price and 6 kg m–3 higher than that of Nomini. In the 2000 to 2001 nursery, Thoroughbred had an average test weight (618 kg m–3) that was similar to that of Callao and exceeded (P 0.05) that of Nomini by 22 kg m–3.
An initial source of Thoroughbred Breeder seed was developed in 2002 via thorough removal of visual variants from a 0.12-ha F11 seed increase strip sown at the Virginia Crop Improvement Association's Foundation Seed Farm. In fall 2003, a purer source of Thoroughbred Breeder seed, derived as a bulked composite of 396 F12 headrows selected among 400 rows evaluated, was provided to the Virginia Crop Improvement Association. Breeder seed of Thoroughbred will be maintained by the Virginia Agricultural Experiment Station under the auspices of the Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg. Authorized seed classes are Breeder, Foundation, Registered, and Certified. Protection of Thoroughbred will be applied for under the amended U.S. Plant Variety Protection Act of 1994. Request for availability of Foundation seed should be directed to Bruce Beahm (804-472-3500), Manager, Foundation Seed Farm, Mount Holly, VA 22524.
NOTES
Accepted for publication September 30, 2004.
REFERENCES
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