Description:
USDA-Basin originated from a multi-origin polycross of four wildland collections from the Central Basin and Range ecoregion chosen for having high fitness at two Great Basin locations in comparison to other populations of similar origin. The four parental wildland collections were chosen for having greater-than-average relative fitness when grown at Nephi, Utah and Wells, Nevada compared to other populations from the same ecoregion, seed transfer zone, and phylogeographic genetic group. The USDA-Basin parental collections originated from four Nevada sites within the Central Basin and Range ecoregion and seed transfer zone 4, and all were within the Western Great Basin-South (WGBS) phylogeographic genetic group (Massatti et al., 2018) (for parent collection information see, Waldron et al., 2025, Registration of 'USDA-Basin' and 'USDA-Wasatch' bluebunch wheatgrass, originating from and adapted to the Central Great Basin of the western USA, J. Plant Registrations). We dug five vigorous plants from each of the four parental sources of USDA-Wasatch at the Wells evaluation nursery in December 2016 and they were polycrossed in isolation in the greenhouse during January 2017 with harvested seed designated Basin-cycle-1A. Seed set was low from the greenhouse crosses and many of the selected plants died so an additional five plants of the four parental sources were dug from the Wells nursery in August 2017, transplanted to isolated crossing blocks at a location near Logan, UT, and allowed to polycross. Seed was then harvested by plant in 2018, bulked, and the new population designated as Basin-cycle-1B. Both years of polycrosses (cycle-1A and cycle-1B) resulted in low seed set, so this was followed by a cycle of random mating of 90 plants for Basin-cycle-1 (approximately equally from cycle-1A and cycle-1B seed) to increase linkage equilibrium and genetic stability; and the seed was harvested in 2019 and the new population designated as Basin-cycle-2. Following the cycle of random mating, 200 seedlings of Basin-cycle-2 that emerged when sown at a depth of 4-cm were planted into an isolated crossing block in 2020 at the Utah State University (USU) Blue Creek Dryland Research farm, near Howell, UT. Beginning in 2021, seed was harvested, bulked, and declared as breeder seed.