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a Dep. of Plant and Soil Sciences, Oklahoma State Univ., Stillwater, OK 74078-6028
b Dep. of Entomology and Plant Pathology, Oklahoma State Univ., Stillwater, OK 74078-6028
* Corresponding author (jlc{at}mail.pss.okstate.edu)
‘OK 169’ alfalfa (Medicago sativa L.) (Reg. no. CV-200, PI 618615) was developed by the Oklahoma Agricultural Experiment Station and released in 2000. OK 169 has a broad genetic base resulting from strain crosses and indirect selection among and within adapted alfalfa cultivars and germplasms for pest resistance, tolerance to environmental stress, seed production, and general adaptation. An equal blend of seed of seven strains was produced, each of which was the result of interpollination of persistent plants from the best cultivars and experimental strains in separate field tests. One test was at Stillwater, two were at Perkins, and four were at Chickasha, OK. Each test consisted of six replicates of each entry and was part of the Oklahoma Cultivar Evaluation Program. During the fourth to sixth production year, plants of the highest yielding entries produced seed on-site using wild bees (primarily Bombus spp. and Apis mellifera L.) for pollination. Cultivars and experimental strains used for pollen and seed sources were selected for yield and persistence. At each site, plots (1 by 5 m) had thinned to 20 to 30 plants/m2 in inferior entries and 40 to 50 plants/m2 in the good ones. Inferior entries in the tests were cut just prior to flowering to eliminate their pollen. Parentage of OK 169 traces to 26 released cultivars and germplasms and 20 diverse unreleased experimental strains. The approximate contribution from the sources are ‘555’ (Woodward and Miller, 1989) (7.8%); ‘Cimarron’ (PVP 7900062) and OK 51 (Caddel et al., 1992b) (6.6% each); ‘OK 49’ (Caddel et al., 1992a) (5.3%); ‘630’ (North American Alfalfa Improvement Conference, 2000) and ‘655’ (3.9% each); ‘624’, ‘636’, ‘5432’ (Woodward et al., 1987), ‘Archer’, ‘DK 135’, ‘WL 320’ (Hanson et al., 1987b), and 6 strains (2.6% each); and ‘5364’ (Woodward et al., 1990), ‘Acclaim’, ‘Action’, ‘Apollo’ (Moutray, 1983), ‘Arc’ (Devine et al., 1975), ‘Crockett’ (PVP 8900278), ‘Dynasty’, ‘Edge’, ‘Good As Gold’, ‘Magnum+’, ‘Pro-Cut’, ‘Riley’, ‘Southern Special’ (Hanson et al., 1987a), ‘Sure’, and 14 strains (1.3% each).
Forage yield production in Oklahoma for OK 169 was evaluated for four generations, syn 0 (seed blended from seven experiments) to syn 3, as part of our alfalfa cultivar testing program, and the results are presented as a percentage of the test means. Syn 0 averaged 102.4% in eight tests for three production years. Syn 1 averaged 103.0% in three tests for three production years. Syn 2 averaged 103.1% in four tests for three production years. Syn 3 averaged 102.4% in seven tests for three production years and four tests for one production year. Considering 100% is the average of the entries in each test, OK 169 averaged about 3% higher than average, which is as good as any well-tested cultivar from public or private breeding programs. These forage yield results illustrate the stability across generations for this genetically broad base population. OK 169 may be used for hay, haylage, or nonabusive grazing by livestock.
Standard pest resistance tests (North American Alfalfa Improvement Conference, 1999) indicate OK 169 has high resistance to Fusarium wilt [caused by Fusarium oxysporum Schlechtend.:Fr. f. sp. medicaginis (Weimer) W.C. Snyder & H.N. Hans], resistance to bacterial wilt [caused by Clavibacter michiganensis subsp. insidiosus (McCulloch)], and the spotted alfalfa aphid [Therioaphis maculata (Buckton)]. It exhibits moderate resistance to Phytophthora root rot (caused by Phytophthora megasperma Drechs.) and low resistance to anthracnose (caused by Colletotrichum trifolii Bain & Essary) and the blue alfalfa aphid (Acyrthosiphon kondoi Shinji), biotype BAOK90, collected in Oklahoma. On the basis of parentage, it also probably possess low-to-moderate resistance to Verticillium wilt (caused by Verticillium albo-atrum Reinke & Berthier), and pea aphid [A. pisum (Harris)].
Seedling tests for resistance to the spotted alfalfa aphid and to blue alfalfa aphid were conducted at Stillwater, OK. The percentages of seedlings exhibiting resistance after infestation with aphids collected in Oklahoma were: spotted alfalfa aphid - OK 169 = 42, ‘Baker’ (R) = 50, and ‘Caliverde’ (S) = 2; and blue alfalfa aphid - OK 169 = 15, ‘CUF 101’ (R) = 29, and Arc (S) = 4 [(R) = Resistant; (S) = Susceptible]. Tests for resistance to the following diseases were conducted by Crop Characteristics, Inc., Farmington, MN, and presented as percent resistant plants: Fusarium wilt - OK 169 = 56, ‘Agate’ (R) = 54, MNGN-1 (S) = 5; bacterial wilt - OK 169 = 38, ‘Vernal’ (R) = 42, ‘Narragansett’ (S) = 2; Phytophthora root rot - OK 169 = 26, Agate (R) = 43, ‘Saranac’ (S) = 5; and anthracnose (race 1) - OK 169 = 13, Arc (R) = 65, Saranac (S) = 3.
Fall dormancy for OK 169 is approximately 4.6, compared with Saranac = 4 and Archer = 5 (1 to 9 scale, where 9 is very non dormant). Flower color for OK 169 is about 95% purple and 5% variegated. Estimation of contributions from each of the major alfalfa germplasm groups is impossible because there was no way of knowing the pollen contribution of any of the diverse parental cultivars or germplasms.
Seed increase is limited to syn 2 generation for Breeder, syn 3 for Foundation, and syn 4 for Certified classes. Maximums of three and five harvest years are permitted for fields producing Foundation and Certified seed, respectively. Seed shall be sold by cultivar name only as a class of Certified seed. Production and marketing rights will be exclusively assigned by the Oklahoma Agricultural Experiment Station to a licencee, who may apply for plant variety protection.
Fifty grams of syn 3 seed will be provided to upon written request to the corresponding author and agreement to make appropriate recognition of its source when this germplasm contributes to the development of a new germplasm, cultivar, hybrid, or strain cross. Request for seed from outside the USA should be accompanied by the appropriate customs and control documents.
NOTES
Contribution from the Oklahoma Agric. Exp. Stn. Registration by CSSA. The authors acknowledge Crop Characteristics, Inc., Farmington, MN, for evaluation of this cultivar.
Accepted for publication July 31, 2001.
REFERENCES
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