Location: Forage and Range Research2018 Annual Report
Objective 1: Improve pasture and rangeland management practices and forage nutritional quality through improved genetics for structure/variation, stand establishment, forage quality, nutrient cycling and persistence characteristics for use on disturbed and semi-arid rangelands in the Great Basin and eastern Upper Mojave Desert, through collection, characterization, improvement and evaluation of grass, legume, and forb germplasm. (Objective C.2, NP 215 Action Plan) Objective 2: Develop grass, legume, forbs, and sub-shrub perennial germplasms/cultivars with increased stand establishment and persistence, seed production, and forage yield and quality on dry, harsh disturbed rangelands of the western US. (Objective C.2, NP 215 Action Plan) Objective 3. Develop breeding strategies and improved grass and legume germplasm for use on pastures and turf under low inputs in the Intermountain West. (Objective E.1, F.2, G.1, J.1, NP 215 Action Plan) Objective 4: Identify grass, legume, and sub-shrub species and mixtures that have increased forage biomass and quality for fall and winter grazing on semi-arid rangelands. (Objective A.1, C.2, NP 215 Action Plan) Objective 5: Identify and describe trait inheritance, quantitative trait loci (QTL), and association mapping for rhizome development, fall and winter forage yield and quality, salinity tolerance, winter hardiness, heading and flowering date, turf quality, and selenium and other heavy metal uptake for improved forages using genomic techniques. (Objective C.2, NP 215 Action Plan) Objective 6: Develop integrated management strategies that decrease invasive weed seed banks, increase biodiversity through the establishment of grass, legume, forb mixtures, and develop plant mixtures that reduce wildfires on salt desert and sagebrush shrub lands in the Great Basin. (Objective B.1, NP Action Plan 215)
The semi-arid and arid rangelands and irrigated pastures of the western U.S. provide a broad array of ecosystem services, including livestock forage, a diversity of native plants, pollinators, animals, and recreational activities. Many of these regions are classified as severely disturbed and non-productive. Moreover, based on predicted climate change models for semi-arid regions, environments will become hotter and drier, increasing the already high rate of rangeland and pasture degradation, resulting in the invasion of annual grasses, increasing wildfire frequency, and reducing forage productivity. Thus, in water-limiting environments, there is a need to develop grasses, legumes, and forbs that will establish under drought, compete with invasive weeds, and persist with adequate forage production and quality to meet the needs of wildlife and livestock producers throughout the year. Increasing digestibility in pasture grasses by 1% results in a 3% increase in livestock gains. The Forage and Range Research Lab (FRRL) combines the disciplines of plant breeding, molecular biology, and ecology in conducting experiments to better understand the genetic mechanisms and pathways of seedling establishment, persistence, competition, forage yield and quality, and other abiotic stresses to develop improved plant materials and management practices for use on these western U.S. rangelands and pastures. These plant materials and management strategies will improve sustainability by reducing the impact of wildfires and invasive weeds, improving wildlife habitat, and conserving, restoring, renovating, and reclaiming degraded landscapes.
This is the final report for this project which terminated in February 2018 and has been replaced by a bridging project 2080-21000-016-00D, “Develop Improved Plant Genetic Resources to Enhance Pasture and Rangeland Productivity in the Semiarid Regions of the Western U.S.”, while the research plan for the next five years undergoes Office of Scientific Quality Review. For additional information, see the report for the bridging project. Significant progress was made over the course of this project toward all objectives. Objective 1: Collections of sideoats gramma, big galleta grass, rushy milkvetch, Utah trefoil, and Lewis flax were made from the Mojave Desert and Great Basin. Morphological and/or genetic diversity studies of these collections were completed. Hybrids made from selected sideoats and big galleta collections were transplanted at Mojave Desert and Utah research sites for observation and selection. Seed was harvested from crossing two of the Utah trefoil populations that were identified as being superior for agronomic traits. This material provides an excellent starting point for developing the first improved germplasm of this species for use in rangeland restoration efforts. Objective 2: New pre-variety germplasms of Searl’s prairie clover were released that improve biodiversity and pollinator efficiency on semiarid rangelands. These native forb releases, designated as Fanny, Bonneville, and Carmel are adapted to differing habitats with variable annual precipitations, and provide a genetically diverse array of genotypes that biologically fix nitrogen as well as provide food for wildlife and native pollinators. There is a need for native grass species that can be utilized for restoration of degraded landscapes in drought-prone regions of the western U.S. As such, ‘Columbia’ bluebunch wheatgrass, ‘Trailhead II’ basin wildrye, and ‘Bannock II’ thickspike wheatgrass were developed and released. These perennial native grasses are adapted to a range of habitats and are important forage for livestock and native wildlife. They were selected for greater seedling establishment and seed production. Salina wildrye is a native perennial grass that could be useful for rangeland restoration. However, its poor seed production has prevented this grass from securing a foothold in the seed industry. Two cycles of selection for more seed heads resulted in 40 percent more seed heads and 37 percent more seed yield per plant. These results indicate that salina wildrye seed yield can be improved through plant breeding. As ecosystems experience increased frequency of drought, weed invasion, and wildfire there is a need for grasses that establish and persist under harsh conditions. As such, ‘Stabilizer’ Siberian wheatgrass was developed and released due to its rapid establishment, persistence, and ability to compete against troublesome weeds such as cheatgrass and medusahead rye. ‘Foragecrest’ crested wheatgrass was also developed and released for its ability to establish, persist, and produce forage on the western U.S. rangelands that receive less than 300 millimeters of annual precipitation. To develop an improved tall wheatgrass cultivar with increased forage production and nutritional quality, two studies were completed that described the genetic variation for agronomic traits within National Plant Germplasm System collections and known cultivars. Included in the final selection were parent clones originating from PI’s 21878, 109452, 578680, 442631, and the cultivar Alkar. Commercial seed of this new plant material is being produced, pending official cultivar release. Objective 3: Breeding and selection for improved forage production and nutritive value resulted in improved populations of meadow bromegrass, orchardgrass, and tall fescue. ‘Arsenal’, a new meadow bromegrass cultivar was released with improved drought tolerance and nutrition under non-irrigated pasture settings. Two orchardgrass germplasm were released for use in orchardgrass breeding programs. UTDG-101, is a late-maturing orchardgrass germplasm noted for its improved forage quality and increased winter tolerance, and USDA-UTWH-102 was derived from high elevation orchardgrass germplasm selected for improved winter hardiness. An evaluation to determine the low-input turf potential of drought tolerant wheatgrasses was completed. Crested, thickspike, and western wheatgrasses when managed under low irrigation generally exhibited less ground cover, but had darker green color, than tall fescue and Kentucky bluegrass. Genetic estimates indicated that selection for increased turfgrass quality in these wheatgrass species would likely result in improved cultivars suitable for low-input turf applications. Objective 4: ‘Snowstorm’, a new variety of forage kochia was developed and released. Forage kochia is a semi-shrub that has been seeded on rangelands for fall and winter forage and been shown to provide needed protein and reduced winter feed costs by 25 percent. Snowstorm is 64 percent taller, produces 68 percent more forage, and has improved protein and digestibility compared to the previously available variety. The potential of small burnet as a winter forage was studied, and it was determined that small burnet protein content is sufficient to meet ruminate animal needs through the growing season and into winter months. Its forage nutritive value during this period was far superior to any cool season grass or forage legume, including alfalfa. Current breeding efforts have resulted in lines that persist with high forage production. Collaborative research with private producers in Cascade, Montana, identified a mixture of meadow bromegrass, intermediate wheatgrass, small burnet, and alfalfa with great potential for winter forage feeding. This mixture is being tested against other mixtures and an economic analysis will be done to determine the sustainability of winter grazing in the region. Objective 5: Rhizomes are an important evolutionary adaptation in plants. A major quantitative trait locus (QTL), a DNA marker of a chromosome region containing genes of significance for rhizome development, was found on the distal end of chromosome 6 in perennial wildrye, setting up the potential of sequencing and developing more precise DNA markers of this important plant trait. Grasses that flower later would enhance their use in grass-legume mixtures. Several genes were found associated with late flowering in orchardgrass. These genes are being converted into molecular markers and are being used for breeding within the USDA-ARS and in cooperation with a private company. Intermediate wheatgrass is a dual-purpose perennial grain and forage crop. A high-density linkage map of intermediate wheatgrass was developed and then used to; 1) uncover the genetic architecture of seed weight and size in intermediate wheatgrass, and 2) assemble the genome sequence for this species. This genome sequence will be publicly available and used to investigate genome relationships between relatives of intermediate wheatgrass including wheat. DNA markers were developed to distinguish among types of Kentucky bluegrass cultivars, which are now being used by companies and universities for hybrid detection, apomixis, and to determine relationships among bluegrass varieties. In addition, DNA assays using three candidate genes, were developed for measuring salt tolerance, resulting in the identification of salt tolerant Kentucky bluegrass breeding lines. The breeding lines and assay are currently being used in partnerships with companies on other Kentucky bluegrass lines as well as other turf species. Objective 6: A comprehensive inventory and analysis of shrub reduction technologies and re-seeding with improved plant materials was completed. After applying current shrub reduction methods, native shrubs did not increase, and forbs generally declined over time; however, large increases in perennial grasses were observed, suggesting that seeding efforts enhanced their establishment in the understory areas. Further research is needed to understand the causes of forb mortality, and to decipher how greater increases of non-native relative to native seeded species will influence species diversity change at rangeland restoration sites. A study on establishment and survival of seeded species was completed that indicated that legacy effects from past land use (i.e., previous agronomic cultivation and production) should be considered when planning restoration projects. Vegetation structure and plant community responses to a two-way chain-harrow treatment and broadcast plantings were evaluated at eight Wyoming big sagebrush sites in Utah. These sites differed in land-use history; five were cultivated for dryland wheat production during the 1950-1980s then seeded with introduced forage grasses, while three had not been exposed to this land-use legacy. Five years after the chain-harrow treatment, mature sagebrush cover remained reduced for both land-use histories, yet density of sagebrush seedlings and broom snakeweed increased on the previously cultivated sites. In addition, perennial forb cover increased on the previously cultivated sites, whereas, perennial grasses increased at the non-cultivated sites. Results indicated that variable plant response to sagebrush reduction and re-seeding is possible within the same ecological site, and that legacy effects due to past cultivation should be considered when planning restoration projects.
1. Gene discovery for late flowering in grasses. Perennial forage grasses are the basis of the meat and dairy industry, providing essential nutrition to ruminant animals. Because these grasses require expensive nitrogen inputs, there is a trend towards grass-legume mixed pastures that require less inputs while increasing forage mass and nutritive value. However, most grasses switch from vegetative to flowering (reproductive) tillers before alfalfa and other legumes, thereby greatly diminishing the anticipated improved nutritive value. ARS researchers in Logan, Utah, have identified late-flowering genes in orchardgrass and developed molecular markers for rapid late-flowering selection. These late-flowering markers resulted in identification of late-flowering orchardgrass germplasm and provided grass breeders in U.S. and China with a valuable tool to tease apart the timing of flowering from overall seed production potential. These markers enhance the development of grasses specifically for grass-legume mixtures, since previous selection for later flowering in grasses generally decreased seed production, thereby diminishing the profitability and adoption of late-flowering grass varieties.
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