Seed-yield components, reproductive health, and ecological fitness of six Snake River wheatgrass populations

Authors: Jones, Thomas; Monaco, Thomas; Rigby, Craig; Israelsen, Benson

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2025
Publication Date: 5/1/2025
Citation: Jones, T.A., Monaco, T.A., Rigby, C.W. 2025. Seed-yield components, reproductive health, and ecological fitness of six Snake River wheatgrass populations. Rangeland Ecology and Management. 100:38-46. http://doi.org/10.1016/j.rama.2025.01.002
DOI: https://doi.org/10.1016/j.rama.2025.01.002

Interpretive Summary: Snake River wheatgrass is a species widely used for restoration and conservation seedings in the Intermountain West. Seed of Snake River wheatgrass was first made available in 1980 with the release of Secar, followed by the release of Discovery in 2007 and Destination Germplasm in 2023. We estimated fecundity and survivorship separately in transplanted and seeded trials, respectively. Destination exceeded Discovery (in 2022, 2023) for seed yield per plant (61%, 113%), seed number per plant (45%, 82%), seed mass (14%, 18%), seed area (12%, 11%), seed-specific mass (2%, 6%), and spike number per plant (27%, decline of 1%). Destination should be more profitable for seed growers due to its higher seed yield and more effective for land managers due to its enhanced stand establishment, attributed to its greater seed mass, than either Secar or Discovery.

Technical Abstract: Ecological fitness is the product of fecundity and survivorship. We compared six Snake River wheatgrass (Elymus wawawaiensis J. Carlson & Barkw.) populations for ecological fitness, a reproductive-health score, and seed-yield components. We measured fecundity in a transplanted trial in Hyde Park, UT and survivorship (as stand percentage) in a seeded trial In Nephi, UT for two consecutive years. Destination Germplasm was selected directly from ‘Discovery’ for deep-seeding emergence in a greenhouse and for greater spike number in the field. In 2022 (2023), Destination displayed 61.1% (113.0%) greater seed yield per plant than Discovery, 26.6% (no different; P > 0.05) greater spike number, 14.4% (18.1%) greater seed mass, 25.3% (104.0 %) greater seed yield per spike, and 11.6% (11.1%) greater seed area at Hyde Park. Destination (Discovery) displayed 65.8% (34.0%) stand in 2023 and 32.1% (14.1%) stand in 2024. Across the six populations, seed yield per spike exceeded spike number as a seed-yield component, seeds per plant exceeded seed mass, seeds per spike exceeded spike number and seed mass, and seed area exceeded seed-specific mass. Reproductive-health scores were greater for Destination (15 of 16 possible points) than Secar (4) or Discovery (1). Compared to Destination (1.000), relative ecological fitness was much greater for Destination (1.000) than either Secar (0.147) or Discovery (0.302). In summary, Destination (released in 2023) shows great promise relative to its predecessors, Secar (1980) and Discovery (2007) for rangeland revegetation and restoration efforts in the northern Great Basin.