Registration of KS224 Glandular‐Haired Alfalfa Germplasm with Multiple Pest Resistance

KS224 alfalfa (Medicagosaliva L.) germplasm (Reg. no. GP-272, P1572543) was released by the USDA-ARS and the Kansas Agricultural Experiment Station in April 1993. Experimental population KS 186 was produced by intermating Fi plants from a cross of two diploids (2n=2jc= 16), M. saliva L. subsp. falcata var. viscosa (syn. M. glandulosa Davidoff) and M. prostrata Jacq., with KS219, a multiple pest-resistant M. saliva L. (2n=4^=32) (1). Medicago glandulosa is a glandular-haired falcata type (2). The plants are clothed with long-stalked glandular hairs (3). Medicago prostrata is a tiny medic that was found in northern Italy (4) growing under extremely dry conditions in association with xeromorphic shrubs and grasses. It has yellow flowers, and its pods are similar to those of M. saliva. The plants have erect glandular hairs with short stalks (3). Recurrent phenotypic selection (four cycles) was used to increase hair density and distribution on the plants (KS186GH4). In each cycle, selected plants were tetraploids that contained longand short-stalked glandular hairs. KS186 GH4 was subjected to recurrent phenotypic selection for resistance to anthracnose (caused by Colletotrichum trifolii Bain & Essary, Race 1) (one cycle), blue alfalfa aphid (Acyrthosiphon kondoi Shinji) (two cycles), pea aphid (A. pisum Harris) (two cycles), spotted alfalfa aphid [Therioaphis maculata (Buckton)] (two cycles) and two cycles to increase hair density and distribution. Independent culling was practiced, but not all pests were included in each cycle. More than 75 plants were intercrossed by hand pollination in the greenhouse to initiate each cycle of selection. Syn 2 seed (KS224) of the last cycle was produced by intercrossing » 250 Syn 1 plants in a field cage. Honey bees (Apis mellifera L.) were used for pollination. In a 100-plant sample of KS224, all plants contained erect glandular hairs; however, hair density and distribution varied widely among plants. At St. Paul, MN, percentages of resistant plants were as follows (5). For bacterial wilt [caused by Clavibacter michiganense subsp. insidiosum (McCull.) Davis et al. ]: KS224 =13, 'Ranger' (R) = 31, 'Narragansett' (S) = <1; for fusarium wilt [caused by Fusarium oxysporum Schlechtend. :Fr. f. sp. medicaginis (IL. Weimer) W.C. Snyder & H.N. Hans.]: KS224 = 33, Agate' (R) = 54, MNGN1 (S) = 4; and for phytophthora root rot (caused by Phytophthora medicaginis E.M. Hansen & Maxwell): KS224 = 25, Agate (R) = 43, and 'Saranac' (S) = 8. Seedling tests to evaluate resistance to anthracnose, downy mildew (caused by Peronospora trifoliorum de Bary), blue alfalfa aphid, pea aphid, and spotted alfalfa aphid were conducted at Manhattan, KS. Percentages of plants resistant to anthracnose (Race 1) were: KS224 = 77, Arc' (R) = 74, Saranac (S) = 2. The following percentages of symptomless plants occurred in tests with two downy mildew fungus isolates: For 17, KS224 = 84, Saranac (R) = 15, 'Kanza (S) == 0; for 18, KS224 = 90, Saranac (R) = 51, Kanza (S) = 0. Percentages of seedlings surviving after infestation with aphid biotypes in Kansas were as follows. For blue alfalfa aphid: KS224 = 82, 'CUF 101' (R) = 49, Ranger (S) = 2; for pea aphid: KS224 = 73, Kanza (R) = 71, Ranger (S) = 2; and for spotted alfalfa aphid: KS224 = 79, 'Riley' (R) = 71, Ranger (S) = 14. Seed stocks of KS224 are maintained by, and may be requested from, the Department of Agronomy, Throckmorton Hall, Kansas State University, Manhattan, KS 66506-5501. Five grams of KS224 seed are available upon written request. It is requested that appropriate recognition of source be given when KS224 germplasm contributes to the development of a new cultivar or hybrid.