Location: Forage and Range Research2012 Annual Report
1a. Objectives (from AD-416):
Evaluate and develop new germplasm and cultivars with enhanced seed production, germination, seedling vigor, salinity tolerance, winter hardiness, drought tolerance, and forage yield and quality and verify their ability to improve the sustainability and productivity of rangelands and pastures in the semiarid western U.S. • Objective 1: Collect, characterize, and evaluate grass, legume, and forb germplasm for genetic variation, adaptation, establishment and forage characteristics for use on Western rangelands and the rangeland-urban interface. • Objective 2: Describe and identify useful traits for improved forages, using physiological, biochemical, and genomic techniques. • Objective 3: Identify breeding and selection strategies to make plant selection more effective. • Objective 4: Develop germplasm/pre-variety germplasm/cultivars of grasses, legumes, and forbs with improved seed production, seedling establishment, forage production, persistence, and drought tolerance on rangelands of the Western U.S. • Objective 5: Develop and evaluate new plant cultivars that are more tolerant of biotic and abiotic stresses, more competitive, more persistent, and easier to establish and maintain in irrigated pastures in the Intermountain West. • Objective 6: Identify functional differences between invasive weeds and improved plant materials and evaluate potential methods and improved plant materials to diversify crested wheatgrass communities.
1b. Approach (from AD-416):
Combine expertise of a research team of plant breeders, plant physiologists, ecologists, and molecular biologists to acquire, characterize, and breed native and introduced range, pasture, low-maintenance turf, and bioenergy plant materials. There is a need for additional plant materials for the conservation, restoration, renovation, and reclamation of range and forage lands, including irrigated pastures. New releases will provide improved plants needed to establish and maintain economically and environmentally sustainable pastures and rangelands in the semiarid regions of the Intermountain West. Identify new sources of genetic diversity for cultivar development. Describe establishment of grasses, legumes, and forbs characteristics such as ability to sustain high quality forage on disturbed sites under grazing pressure when competing with invasive weeds, and important physiological and biochemical mechanisms. Molecular and cytogenetic approaches will be used to identify and characterize genetic mechanisms to improve efficiency of genetic enhancement and plant breeding. The competitive ability of released plant materials will be enhanced for traits such as seed germination, seedling vigor, rhizome development, salinity tolerance, drought tolerance, and forage quality and yield. The new plant materials will be evaluated for their improved ability to perform key ecological functions, satisfying the diverse needs of our customers. Evaluate potential invasiveness of new plant germplasm.
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. The FRRL develops native and introduced grasses, legumes, forbs, and sub-shrubs (forage kochia) for multiple applications. Hotter and drier climates are predicted that will require plants with increasing levels of abiotic stress resistance (e.g., heat/cold, drought, salt) to sustain agricultural productivity and maintain utility of recreational urban landscapes. Traits of interest for improved plant materials include seed yield, germination, establishment, abiotic stress tolerance, winter hardiness, and increased forage yield and quality. Efforts are currently underway to establish forage kochia and wheatgrass species on the scablands of central Washington to compete with invasive weeds (e.g., cheatgrass and medusahead) and reduce animal intake of lupine (plants toxic to livestock). Research is conducted in perennial ryegrass to determine the relationship between high water soluble carbohydrate content and tolerance to drought and winter injury. Orchardgrass experimental lines produced more biomass under less water, and Kentucky bluegrass lines maintained an acceptable green color and density under lower irrigation amounts. A new Siberian wheatgrass cultivar Stabilizer was released as a low growing, rapidly establishing grass for use on arid and semiarid rangelands in the western U.S. To elucidate the nutrient requirements of invasive weeds (e.g., cheatgrass), research defined their nitrogen requirements and documented that a combination of seasonal controlled burning and pre-emergence herbicides can be used to better manage cheatgrass invasion. As urban growth continues in the western U.S., there will be less water available for irrigation of pastures and urban landscapes. Methodologies were developed to assess turf quality (greenness) under irrigation deficits to identify rhizomatous wheatgrass and Kentucky bluegrass genetic stocks with improved drought tolerance for low-input turf applications. The FRRL pasture research focuses on winter hardiness, and increased grass forage yield and quality. Initial selection among orchardgrass gemrplasms has yielded late-flowering genetic stocks of U.S. and Chinese origin for continued selection for increased uniformity in preparation for release. FRRL scientists have generated thousands of DNA gene sequences from orchardgrass and Kentucky bluegrass to map genes controlling very late flowering (heading date), candidate gene analysis, and assess genetic diversity in orchardgrass. Relationship analyses in orchardgrass, bluebunch wheatgrass, and bluegrass identified unique pools of genetic resources for further variety development. Genotype and transcriptome analysis of intermediate wheatgrass accessions was used to develop functional gene markers for genomic mapping. Medicago GeneChips to identify differentially expressed genes putatively associated with salt stress [i.e., genes for salt tolerance (susceptibility and tolerance)] in alfalfa.
1. Cultivar release for revegetation on dry-harsh disturbed rangelands. As ecosystems experience climate change there is a need to develop grasses that are lower-growing, easily established, and which persist under increased drought, weed completion, and wildfires. ‘Stabilizer’ Siberian wheatgrass cultivar was developed by ARS scientists in Logan, UT as a low growing, rapidly establishing grass for use on arid and semiarid rangelands, roadsides, and as a grass component in fire strip plantings in the Intermountain West, Great Basin, and Northern Great Plains Regions of western U.S. Stabilizer has been extensively evaluated at semiarid sites representative of different ecological regions in northern plains and western U.S. Due to its rapid establishment and persistence, Stabilizer can successfully compete against troublesome weeds such as cheatgrass, medusahead rye and others, which frequently occupy much of the disturbed rangelands and roadsides in the western U.S. Land management agencies (BLM, NRCS, and State Road departments), ranchers, and the seed industry are primary beneficiaries of this release.
2. Linking rangeland soil nutrient patterns with rangeland restoration practices. Patterns of nutrient availability are highly heterogeneous on rangelands, making it difficult to determine the connection between land fertility and the performance of desirable plant species. Experiments determined how seasonal patterns of soil resources impact desirable plant species performance against invasive annuals such as cheatgrass and hologeton. These studies compared soil nutrient uptake in invasive annuals, cheatgrass and halogeton, with perennial plant materials during the fall and spring growing period. This research demonstrated that invasive annuals uptake more soil nutrients in the fall than spring, suggesting that they gain their competitive edge over perennials by growing into the fall while perennials are dormant. The significance of these findings suggests that fall control of these annual weeds may result in an increased establishment of perennials on rangelands occupied with invasive annuals, which is different than what was previously thought.
3. The effect of past land-use and rangeland restoration practices. Humans have effected land-use patterns through cultivation and grazing since the early settlement of the U.S. It is critical to determine the effects of these land-use patterns to make recommendations for restoration of rangelands. In an attempt to understand differences in rangeland fertility across a landscape, experiments were designed to characterize rangelands based on historical dryland farming records. The study found that “islands of fertility” are a natural consequence of heterogeneous rangelands and can be obliterated by past land cultivation. Moreover, it was found by comparing historical dry farm sites to naturalized rangelands in the Great Basin that such land changes require more than 100 years for their recovery and that due to previous land-use may be difficult to restore to their native habitat. These results will assist producers in developing more effective management strategies and thus improve productivity.
4. Factors associated with vegetation change during rangeland rehabilitation. There is need to better understand how management efforts can improve forage production for cattle operations on western U.S. rangelands. Scientists at the FRRL, Logan, UT identified distinct patterns of vegetation change on rangelands seeded to crested wheatgrass. The ability of native species to re-colonize crested wheatgrass stands depended on disturbance type and magnitude, soil properties, and the duration of time since crested wheatgrass was seeded. In addition, a variety of management tactics (i.e., the combined tactics of prescribed burning and herbicide application) reduced invasive annual grass and limited the establishment of new invasive annual grass seedlings, while increasing soil water and nutrient availability during the establishment of crested wheatgrass. This research provides land managers with a greater understanding of how vegetation change continues to be impacted by past management practices, and how future management can be refined to meet producer needs.
5. Foundation seed regeneration and genetic diversity. Maintaining genetic integrity, the association of economically important gene groups (i.e., linkage), and the performance of released cultivars over multiple generations of seed increase continues to be of concern in cross-pollinating grasses. For example, in Russian wildrye, seed being produced is often four generations removed from the original breeder seed. Using molecular marker analysis, ARS scientists at Logan, UT showed that four generations of seed production resulted in a 10% loss of the integrity of such linked groups of genes. However, that loss did not result in a significant loss in agronomic performance in the species. Thus, in Russian wildrye, seed can be increased for at least four generations without dramatic changes in genetic structure and loss of functional linked gene groups that might be associated with changes in agronomic performance.
6. Identification of late flowering loci in orchardgrass. Orchardgrass is a premier forage grass with exceptional nutritional quality. It is used extensively by dairy cattle and horse operations, often in mixtures with alfalfa and clover to improve pasture sustainability. However, orchardgrass typically flowers earlier than alfalfa and clover such that its forage quality is in decline when producers harvest grass/legume pastures based on legume flowering time. ARS scientists at Logan, UT surveyed orchardgrass germplasm from seed banks across the world for later flowering collections, and developed genomic resources and molecular markers to assess the genetic relationships and diversity of these accessions. Furthermore, a genetic linkage map was constructed and genetic loci that control the later flowering trait were identified. Molecular markers in these flowering genes (late flowering) can be used to develop orchardgrass germplasm that is later flowering thus increasing forage quality in orchardgrass alfalfa and clover mixed pastures.
7. Development of gene maps for perennial wheatgrass and wildrye grass. In contrast to domesticated annual crop species, persistent perennial grasses provide for increased management opportunities and ecological services in natural and managed rangelands. Moreover, the world’s most important annual cereals including wheat, barley, and rye have perennial grass relatives that are a reservoir of economically important disease resistance and stress tolerance genes not found in domesticated cereal crops. However, the genomic understanding of perennial grasses (gene mapping and sequencing) for plant improvement lags behind that of most domesticated crop plants. Scientists at the FRRL have completed the sequencing and mapping of genes from native perennial wheatgrass and wildrye species. These maps were used to characterize genes associated with functionally important traits and to identify chromosome regions introgressed from perennial relatives of wheat. These new genomic resources will enable the improvement and utilization of perennial grasses for rangelands.Staub, J.E., Simon, P.W., Cuevas, H.E. 2011. USDA, ARS EOM 402-10 high B-carotene cucumber. HortScience. 46:1426-1427.