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a USDA-ARS, Forage and Range Res. Lab., Utah State Univ., UT 84322-6300
b US Army Corps of Engineers, Engineering Research and Development Center, Cold Regions Research and Engineering Laboratory (ERDC-CRREL), Hanover, NH
* Corresponding author (kevin{at}cc.usu.edu)
‘Bozoisky-II’ Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski], (Reg. no. CV-244, PI 639689) was developed by a research team at the USDA-ARS Forage and Range Research Laboratory at Utah State University, Logan, UT, and was released on 2 June 2005 in cooperation with the Utah Agricultural Experiment Station. Bozoisky-II was evaluated in field trials as Syn-A and Syn-B and as part of the Strategic Environmental Research and Development Program (SERDP) project CS-1103 to identify resilient plant characteristics and develop wear resistant plant cultivars for use on military training lands. Bozoisky-II was selected for seedling vigor (emergence from a deep planting depth), seed mass, seed yield, vegetative vigor, total dry matter production, and response to drought. Bozoisky-II has a much broader genetic base than other Russian wildrye cultivars and has been evaluated extensively on rangeland sites in the western USA. Seedling establishment of Bozoisky-II has been equal to or greater than commercially available cultivars.
The 15 parent clones of Bozoisky-II were derived from two base population synthetics A (nine clones) and B (six clones) that were originally assembled in 1981. Synthetic-A was comprised of 18 plants from the following accessions: ‘Vinall’ (one plant; Rogler & Schaaf, 1963); P210 (one plant; accession from the Natural Resources Conservation Service); PI 314675 (one plant); PI 406468 ‘Bozoisky’ (nine plants); PI 406471 ‘Shortandinsky’ (one plant); PI 314082 (two plants); and Jones & Keller no. 447 (three plants). Synthetic-B was comprised of 12 plants from the following accessions: Vinall (one plant); P210 (one plant); PI 272136 (one plant); PI 314675 (one plant); PI 369234 (one plant); PI 406468 Bozoisky (four plants); PI 406469 (one plant); and PI 314082 (two plants). A total of three cycles of recurrent phenotypic selection for plant vigor, increased seed weight, and the ability of seedlings to emerge from a 7.6-cm planting depth (Maguire, 1962) was completed within each synthetic population from 1983 to 1987.
In 1988, 20 clonal ramets from each of 14 clones selected from synthetic-A and seven clones from synthetic-B were established in a crossing block at Evans Research Farm near Logan. Vegetative vigor (visual score 1 to 9; 1 = worst and 9 = best) was recorded in 1989, 1990, and 1991. Seed yield (g plant–1) was evaluated on a clonal basis in 1989 and 1990. In 1991, based on vigor and seed yield, 15 superior clones were identified and allowed to intercross. The unselected clones were rogued before anthesis in 1991. An equal weight of seed from each of the 15 selected clones was bulked and designated as Breeder seed. Breeder seed was produced in 1991, 1992, and 1993 from the same nursery of 15 clones.
When combined across two locations, Bluecreek, UT, and Green Canyon, UT, Bozoisky-II is significantly taller (92.9 cm) than ‘Mankota’ (84.3 cm) (Berdahl et al., 1992) and ‘Tetracan’ (85.2 cm) (Lawrence et al., 1990). At both locations, Bozoisky-II (10.8 cm) has a significantly longer inflorescence than ‘Bozoisky-Select’ (9.0 cm) (Asay et al., 1985) and Mankota (8.5 cm). Bozoisky-II Russian wildrye is a diploid (2n = 2x = 14) and has the same ploidy level as the commercially available cultivars Bozoisky-Select, Mankota, Swift (Lawrence, 1979, 1980), and Vinall.
Relatively slow seedling growth and development are the most serious limitations within Russian wildrye. Selection emphasis on Bozoisky-II was for increased seedling vigor during establishment. In seeded trials at Guernsey, WY (established 2004), King Hill, ID (established 2003), and Soda Lake, WY (established 1991), when planted on a pure live seed basis (PLS), Bozoisky-II had significantly more seedlings per unit area than did Bozoisky-Select and Tetracan. Bozoisky-II was evaluated in the Northern Plains Regional Trials established in 1999 at Bluecreek; Green Canyon; Mead, NE; Sidney, NE; Mandan, ND; and Miles City, MT for initial stand, persistence, and dry matter forage production. Initial stands and persistence of Bozoisky-II were similar to Bozoisky-Select and Mankota combined over and within locations. However, Bozoisky-II established significantly better and yielded greater than the tetraploid cultivar Tetracan and the tetraploid germplasm Tetra-1 (Jensen et al., 1998). Dry matter yields of Bozoisky-II, Bozoisky-Select, and Mankota were similar except at Green Canyon, where Bozoisky-II had significantly greater (P < 0.05) yield than Mankota.
Within the Great Basin and Northern Great Plains, Bozoisky-II is adapted to sage-brush, mountain-brush, and pinyon-juniper on arid to semiarid rangelands. It is best adapted to loam and clay soils; however, acceptable stands can be obtained on a wide range of soil types. Russian wildrye's resistance to drought exceeds that of crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schultes] (Asay and Jensen, 1996).
Amplified fragment length polymorphisms (AFLP) (Vos et al., 1995) were used to compare Bozoisky-II to other released cultivars of Russian wildrye. A neighbor-joining tree demonstrated that Bozoisky-II contains substantially more genetic diversity than current diploid and tetraploid cultivars (Page, 1996; DeHaan et al., 2002). The average similarity coefficient (0.5823) among Bozoisky-II genotypes was significantly less (P < 0.05) than Cabree, Tetracan, and Tetra-1 and numerically less than the other five cultivars that were evaluated. Analysis of molecular variance (AMOVA) indicated that Bozoisky-II contains substantially more DNA polymorphisms (Excoffier et al., 1992; Leonard et al., 1999) than the other eight cultivars that were evaluated. Moreover, the average number of polymorphisms between Bozoisky-II and the other eight Russian wildrye cultivars were significantly greater (4.4 to 17%) than the average number of polymorphisms within respective cultivars. The neighbor-joining tree and AMOVA indicated that Bozoisky-II is more closely related to Bozoisky-Select than to the other seven cultivars, which is consistent with its breeding pedigree.
Breeder, Foundation, and Certified seed classes will be recognized. Breeder seed will be maintained by the USDA-ARS Forage and Range Research Laboratory at Logan. Foundation seed will be produced by the USDA-ARS at Logan and distributed to seed growers by the Utah Crop Improvement Association. Protection will be applied for under the U.S. Plant Variety Protection (PVP) Act of 1970. Conditions of this PVP will specify that seed of the cultivar Bozoisky-II can be marketed only as a class of Certified seed. Small quantities of seed may be obtained from the corresponding author for at least 5 yr.
NOTES
Utah Agic. Exp. Stn. Journal Article No. 7703. Registration by CSSA.
Accepted for publication August 31, 2005.
REFERENCES
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