Location: Forage and Range Research2013 Annual Report
1a. Objectives (from AD-416):
Objective 1: Collect, characterize and evaluate grass, legume, and forb germplasm for genetic structure/variation, stand establishment, and persistence characteristics for use on disturbed and semi-arid rangelands in the Great Basin and eastern Upper Mojave Desert. (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)
1b. Approach (from AD-416):
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.
3. Progress Report:
The Forage and Range Research Laboratory (FRRL) focuses on the development of improved germplasm for rangeland, pasture, and turf applications, and the identification of best management practices for sustainable agriculture in the western U.S. For Objective 1, collections of sideoats gramma, big galleta grass, Utah trefoil, and Lewis flax were made from the Mojave Desert and Great Basin. For Objective 2, selection continued for improved wheatgrasses, wildryes, fine fescues, and native legumes for sand establishment, rhizome development, salt tolerance, and persistence in dryland areas with predicted increasingly hot/dry climates of the Great Basin. Forage kochia continued to be evaluated for its ability to establish in degraded rangelands and compete with the invasive weeds. Progress in Objective 3,was made through the genetic improvement of pasture plants (tall fescue, orchardgrass, birdsfoot trefoil) and turfgrasses (Kentucky bluegrass, wheatgrasses, and fine-leaved fescue) for low input applications. Field evaluations were initiated to test the effectiveness of biomass production in grass-legume mixtures compared to chemically fertilized monocultures. Turfgrasses (bluegrasses, fine fescues, and wheatgrasses) were evaluated for color and growth under reduced water regimes. For Objective 4, spring and winter forage studies at Cheyenne, WY and Logan, UT were completed with emphasis on intermediate and tall wheatgrass and small burnet. Foundation (stock) seed fields were established for kura clover and dryland alfalfa. Significant progress in Objective 5, was made in understanding the genetic and physiological mechanisms responsible for yield and quality-related traits under salt and water stress in wildryes, orchardgrass, Kentucky bluegrass, and alfalfa. An assessment of gene expression was initiated to determine the genetic basis of forage kochia seed viability, alfalfa and bluegrass salt tolerance, and orchardgrass late flowering and carbohydrate accumulation. Genetic (DNA) markers were developed for economically important traits (e.g., forage kochia seed viability, alfalfa and bluegrass salt tolerance, orchardgrass late flowering and carbohydrate accumulation) for their localization on genetic maps. Experiments were also initiated to identify genes associated with freezing tolerance in orchardgrass, rhizome development (spreading) in wildryes, salt tolerance and spreading growth habit in alfalfa, and the accumulation of heavy metals in forage grasses grown on contaminated soils. For Objective 6, Utah shrubland sites were ecologically classified (USDA-NRCS Ecological Site Inventory System) and monitored to develop improved range management protocols. Studies to evaluate the interaction between improved plant establishment and competition with cheatgrass were initiated to examine the effect of mowing, burning, and herbicide applications on cheatgrass seed banks. Previous research leading up to these objectives is described in the expired project #5428-21000-012-00D annual report.
1. Plant development for western rangelands, pastures, and roadsides. Since 1984 the FRRL has developed and released 42 cultivars for use on degraded rangelands and pastures, and reduce inputs in roadsides turfgrass applications. Since 2006 it has released fourteen cultivars including Russian wildrye (1; released 2006), wheatgrass (6; released 2007-2012), forage kochia (1; released 2012), bottle brush squirreltail (5; 2011-2012) and ricegrass (1; released 2006) cultivars that have established themselves in the market place and now provide significant resources for improved rangeland productivity under environmental considerable stresses (water, salt) present in the Great Basin. This statement is substantiated by the fact that a significant portion of the BLM public “seed buys” for restoration of disturbed landscapes (principally from wildfires) are comprised of FRRL plant materials (e.g., June 2012, 42% and October 2012, 47%).
2. Improved germination and stand establishment in forage kochia. Forage kochia is an introduced nutritious, semi-shrub that has been seeded on western U.S. rangelands for fall and winter forage; however, its widespread acceptance has been reduced by its poor seedling germination and hence reduced stands. The ARS-FRRL in Logan, UT, completed a study showing that two subspecies of B. prostrata, grisea and virescens, age of seed, and planting date all affect forage kochia seed germination in the field. At 45 days after planting, when germination was at or near maximum, current year’s harvested seed of subspecies grisea had field germination substantially higher compared to subspecies virescens. Year-old seed of both subspecies germinated at less than 15% during the same planting dates of January through April. Thus, planting in January or February using current year’s harvested seed of subspecies grisea provided the best forage kochia germination, and hence increased the likelihood of a successful stand. These results have been disseminated to livestock producers through several regional meetings in Montana, Wyoming, and Utah during the winter of 2013. The use of forage kochia during the fall and winter grazing periods can reduce overall animal feeding costs by up to 25%.
3. Discovery of candidate genes associated with plant architecture of rangeland grasses. Grass flower and stem branches show architectural differences that ultimately determine the number of seeds and stems produced by each plant. Flower branches of Triticeae grasses are usually contracted into a spike formation, with the number of flowering branches (spikelets) per node conserved within species and genera. Perennial Triticeae grasses of the genus Leymus are unusual in that the number of spikelets per node varies, flowering branches may be extended to form a panicle, and vegetative stems may form subterranean rhizomes. Chromosome regions associated with differences in the number, size, and density of flower and stem branches, including subterranean rhizome branches were identified by ARS scientists in Logan, UT, in experimental populations derived from two divergent Leymus species using 360 DNA markers derived from branch meristem expressed genes. Alignments of genes, mutations, and quantitative trait loci controlling similar traits in other grass species were identified using the Brachypodium genome reference sequence. These experiments provided evidence that genes controlling flower and stem branch architecture are conserved among the grasses, are governed by natural selection, and can serve as possible targets for improving seed, forage, and grain production.
4. Understanding the interactions between plant establishment and soil nutrients. The ARS-FRRL in Logan, UT, has been a participant of a federally-funded ecosystems assessment project titled “Invasive Annual Grasses in the Great Basin Ecosystem: Applying Ecologically-based Invasive Plant Management (EBIPM)” in the Intermountain Region, which ended in FY 2012/13. The project used EBIPM to develop management principles that could be used for integrated ecosystem assessment and management of degraded landscapes. It enhanced land manager understanding of ecological concepts and management methods, program cost, and linkages among science and management. In conjunction with this project, the FRRL evaluated the responses of invasive weeds to concentrations of nitrogen and phosphate, and found that plant growth rate depended primarily on nitrogen acquisition from the soil (cultivated or uncultivated) and that invasive weeds acquired nitrogen earlier than other rangeland plants. Early weed acquisition of soil nutrients leads to mineral depletion; poor stand establishment, and reduced plant growth of productive native and non-native rangeland plants.
5. Improved germination and stand establishment in native legumes. Although native legumes and forbs increase the biodiversity of western U.S. rangelands leading to improved productivity and enhanced habitats for herbivores, they are difficult to establish. The ARS-FRRL in Logan, UT, initiated greenhouse and field germination studies to solve these problems. Critical factors were identified to maximize seedling establishment in three legume species native to the Great Basin Region of the western U.S.; basalt milkvetch, western prairie clover, and Searls’ prairie clover. All three species emerged faster when the seed was scarified; however, emergence was least affected in basalt milkvetch. Companion field studies showed that spring plantings of the western and Searls’ prairie clovers were most successful and that fall plantings were best for basalt milkvetch. These results are being used to establish commercial seed fields of these species.
Bushman, B.S., Warnke, S.E., Amundsen, K.L., Combs, K., Johnson, P.G. 2013. Molecular markers highlight variation within and among Kentucky bluegrass varieties and accessions. Crop Science 53:2245-2254.