Registration of ‘Alpha’ Smooth Bromegrass

'Alpha' smooth bromegrass (Bromus inermis Leyss.) (Reg. no. CV-20, P1 584449) was developed by the forage grass breeding and genetics program of the Wisconsin Agricultural Experiment Station, Madison, WI, and released in August 1993. Alpha was tested as experimental synthetic B9. It was developed through five cycles of tandem phenotypic recurrent selection in which the selection criteria varied considerably among cycles. The parentage of Alpha derives from a broad-based smooth bromegrass germplasm pool that included a large number of plant introductions and cultivars, the identity of which are unknown. It is the same pool from which the cultivar Badger was derived (1). Between 1959 and 1965, this germplasm pool was subjected to two cycles of phenotypic recurrent selection for resistance to seedling damping-off (caused by Pythium spp.), using a Pythiiim-mfested soil medium in the greenhouse. The third cycle of phenotypic selection, for resistance to brown leafspot [caused by Drechslera bromi (Died.) Shoemaker] using natural inoculum at Arlington, WI, was completed in 1969 when seed was harvested from 62 plants without disease symptoms. In cycle four, seed of the 62 halfsib families was planted in replicated rows at Arlington and overseeded with alfalfa (Medicago saliva L.) and oat (Avena saliva L.). After 2 yr of a three cuts per year management system, an equal number of 15-cm cores were dug from each of the eight families with the highest mean recovery after cutting, based on visual scores. The cores were polycrossed to form the B8 synthetic in 1973 (2). In cycle five, 270 spaced plants of B8 were screened for reaction to infection by naturally occurring brown leafspot inoculum at Arlington in 1975, 1976, and 1977. Forage samples were collected from each plant. Twenty-three plants were selected based on low 3-yr mean disease reaction and high 3-yr mean in vitro dry matter digestibility (IVDMD), using the two-stage procedure of Marten and Barnes (3). These 23 plants were polycrossed in a 10-replicate crossing block in 1981 and 1982. Alpha has been tested in cultivar trials at six locations (Arlington, Ashland, Lancaster, Marshfield, and Spooner, WI, and Ames, IA) for a total of 16 location-year combinations. Alpha averaged 0.9% higher mean forage yield than 'Rebound' in these trials. It ranked second (following Badger) in IVDMD in both Wisconsin and Iowa trials, averaging 13 g kg"' (2.0%) higher than Rebound. Alpha averaged 14% greater average daily gain than Rebound when both cultivars were grazed by ewes and lambs (Ovis aries) in a replicated grazing experiment at Arlington in 1985. The relative maturity of Alpha was similar to that of other smooth bromegrass cultivars when tested in Wisconsin. Alpha had excellent rhizome spreading ratings after 2 yr at Ames, IA. It was the highest-ranked cultivar for persistence with alfalfa in six grassalfalfa mixture trials conducted at four Wisconsin sites, averaging 10% higher than Rebound. It rarely shows symptoms of brown leafspot, the only serious disease of smooth bromegrass in the upper Midwest, with a level of resistance equal to that of Badger. Alpha is well adapted to a wide range of soil types and climates in the north-central and northeastern USA. It has excellent winterhardiness and persistence under either a three-cut hay or rotationally grazed pasture management. It has produced average to above-average seed yields at locations in Wisconsin ranging from 43 to 46° N lat. Its primary intended uses, in either pure stands or mixtures with alfalfa, are for hay or silage production under a three-cut management system and for pasture in a rotational-grazing system. Breeder seed of Alpha smooth bromegrass will be maintained by the Dep. of Agronomy, University of Wisconsin-Madison. The exclusive rights to produce foundation and certified seed of Alpha were assigned to Forage Genetics, Inc., N5292 Gills Coulee Rd., West Salem, WI 54669. Seed multiplication of this cultivar will be limited to Foundation and Certified classes, which will be one and two generations advanced from breeder seed, respectively.