Project : USDA ARS

ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Research Project #435977

Research Project: Improved Plant Genetic Resources and Methodologies for Rangelands, Pastures, and Turf Landscapes in the Semiarid Western U.S.

Location: Forage and Range Research

2023 Annual Report

Objectives
The semiarid rangelands, irrigated pastures, and turfgrasses of the western U.S. provide a broad array of critical ecosystem services, but invasive weeds, frequent drought, hotter temperatures, wildfires, and other disturbances are increasing the rate of rangeland and pasture degradation and threaten their long-term productivity. Therefore, the long-term objective of the Forage and Range Research Lab (FRR) is to develop resilient, weed resistant, and productive plant materials and methodologies to help prevent and solve these important natural resource issues. Research will be in the areas of (1) Rangeland Conservation and Restoration, and (2) Pasture and Turf Productivity and Sustainability. Specifically, during the next five years we will focus on the following five objectives: Objective 1: Develop new plant materials for pasture, rangeland, and turf systems with increased resilience to harsh and variable environments. Sub-objective 1A: Identify populations of bluebunch wheatgrass wheatgrass [Pseudoroegneria spicata (Pursh) Á. Löve] with superior seedling development under environmental fluctuations. Sub-objective 1B: Elucidate the genetic basis and extent of genotypic variation for drought and salt tolerance in common pasture, rangeland, and turf grasses. Sub-objective 1C: Develop pasture and rangeland grass and legume cultivars and germplasm with improved cold, salt, and drought tolerance. Objective 2: Develop new plant materials and management practices that decrease the impact of invasive species and improve productivity, utility, and restoration of semiarid rangelands. Sub-objective 2A: Develop weed resistant plant materials with improved seed yield, seedling establishment, and persistence for conservation and restoration of rangelands. Sub-objective 2B: Identify seeding methodology that increases establishment of desirable plants and reduces weed invasion on rangelands. Objective 3: Develop new plant materials with improved nutritive value and forage productivity, thereby increasing livestock performance and carrying capacity of pastures and rangelands. Objective 4: Develop new turfgrass plant materials with improved aesthetic value when grown under reduced maintenance conditions. Sub-objective 4A: Identify genetic methods that improve the efficiency of developing reduced-maintenance turfgrass germplasm. Sub-objective 4B: Determine the extent of Genotype x Environment x Management (GxExM) interactions on reduced maintenance turfgrass performance. Objective 5: Identify efficient pasture and rangeland-based grazing strategies that simultaneously improve economic and environmental sustainability of livestock production.

Approach
Traditional plant breeding, augmented by genomics and ecology, multi-location field evaluation, greenhouse microcosm experiment, deficit irrigation and physiological, genomic and molecular marker approaches will be used to achieve project objectives. Sub-objective 1A: Seedling mortality is a threat to revegetation success in semiarid ecosystems. Microcosm experiments will determine the variation for seedling response to environmental gradients of temperature, soil moisture, and nutrients. Sub-objective 1B: Deficit irrigation experiment will determine the feasibility of meadow fescue for the western U.S. Physiological and molecular markers will elucidate the response of turf species to drought and salt stresses; identify and characterize the alien Triticeae genes in wheat that confer salt tolerance and stem rust resistance; and create a DNA map of drought genes in bluebunch wheatgrass. Subobjective 1C: Multi-location evaluation will be employed to develop winter-hardy, drought-tolerant, and/or salt-resistant germplasm of orchardgrass, timothy, and alfalfa. Sub-objective 2A: Native grasses and legumes often lack seed production and establishment. Utah sweetvetch, basalt milkvetch, and Salina wildrye germplasms with improved seed production will be developed. The effect of pre-plant seed treatment on establishment of Utah trefoil will be determined. Genomic selection’s (GS) greatest benefit is when phenotypic evaluation is ineffective; therefore, the potential of GS to improve seed production and establishment in rangeland species will be determined using bluebunch wheatgrass as a model. Subobjective 2B: Many Conservation Reserve Program and Bureau of Land Management plantings in the western U.S. are unsuccessful due to poor establishment of native grasses, legumes and forbs. Seed mixtures that increase seedling establishment success in semiarid regions will be identified. Rapid root development, a potential trait enabling perennial grass seedlings to compete with annual grasses, will be quantified. Objective 3: Recurrent and genomic selection and will develop tall fescue, meadow bromegrass, and tall and intermediate wheatgrass germplasms with improved nutritive value throughout the grazing season. Candidate genes for digestibility will be identified in perennial ryegrass using ribonucleic acid sequencing (RNA-seq) and quantitative trait loci (QTL) analyses. Sub-objective 4A: Kentucky bluegrass and hard fescue have complex genomes that slow their genetic improvement. Genomic and molecular marker approaches will characterize and find functional genes for reduced-maintenance traits. Subobjective 4B: Turfgrass irrigation is not environmentally sustainable, therefore, wheatgrass, bermudagrass, and zoysiagrass will be characterized in mixtures and for color retention in cold temperatures. Objective 5: Reduced dry matter intake (DMI) of pasture by grazing cattle is a major factor limiting livestock performance. Grass-legume pastures that require fewer inputs, have high mass and nutritive value, and have high DMI will be identified.

Progress Report
In support of Sub-objective 1A, ARS scientists at Logan, Utah, made progress in determining the ability of native grasses to survive and flourish under harsh environments associated with weeds, wildfire, and climate change. A seedling growth database with results from five experiments (drought, heat, cold, root development, and nutrient addition) was compiled for a bluebunch wheatgrass seedlings and analyses were initiated to elucidate genomic patterns and divergent groups within a half-sib training population. This database was used to also evaluate trait heritability and correlations between seedling traits and field performance. In support of Sub-objective 1B, to elucidate the genetic basis and extent of genotypic variation for drought and salt tolerance in common pasture, rangeland, and turf grasses, DNA marker development was conducted with the aid of informatics from the genome assemblies of three species. Molecular markers from two sources of salt tolerance were identified. To date, three molecular markers have been verified to be useful in the screening of segregating populations resulting from crosses between salt-sensitive and -tolerant parents. In addition, a paper was prepared that documented that endophyte-infection status did not influence meadow fescue forage mass under deficit-irrigation. In support of Sub-objective 1C, research continued towards the development of pasture and rangeland grass and legume germplasm with improved cold, salt, and drought tolerance. Seed was harvested from selected orchardgrass and timothy plants with superior drought tolerance or winterhardiness and distributed to collaborators in Saskatchewan and Quebec for the next round of evaluation and selection. A new orchardgrass, 'USDA-Yeti’ was released with improved winterhardiness. Performance and persistence data were collected for experimental alfalfa germplasm with results showing that it persists even under grazing conditions typical of those found on western semiarid rangelands. In support of Sub-objective 2A, ARS scientists at Logan, Utah, made progress in developing weed resistant plant materials with improved seed yield, seedling establishment, and persistence for conservation and restoration of rangelands. Field data on seed production, seed retention, flowering and forage mass production was completed in support of a new Utah sweetvetch release. In support of Sub-objective 2B, to identify seeding methodology that increases establishment of desirable plants and reduces weed invasion on rangelands, progress was made towards understanding the value of seed mixtures on rangelands as additional data on cheatgrass, perennial grasses, and pollinator species plant densities and biomass production were collected from rangeland plots. A manuscript on the mechanism of Utah trefoil seed dormancy and field emergence from late-fall and spring seeding was prepared and published in Native Plants Journal. This paper documented that Utah trefoil has both physiological and physical seed dormancy, thus established better from late fall seedings of scarified seeds. In support of Objective 3, ARS scientists at Logan, Utah, continued to develop new plant materials with improved nutritive value and forage productivity. Data analysis in support of a putative new tall fescue cultivar was completed and superior parent plants were selected. In support of developing perennial ryegrass with increased cell wall digestibility, the breeding population was phenotyped using near infrared (NIR) for fiber digestibility and water-soluble carbohydrates, and DNA markers (SNP loci) associated with those traits were mapped onto a new reference genome of the variety Manhattan. The development of orchardgrass with increased water-soluble carbohydrate concentration continued with an evaluation of experimental lines from multiple countries. In support of developing a genomic selection model for forage and grain production traits in intermediate wheatgrass, genomic prediction models were used to select intermediate wheatgrass parent plants with improved seed size, seed retention, seed threshing, and seed yield traits. For Sub-objective 4A, ARS scientists at Logan, Utah, continued to identify genetic methods that improve the efficiency of developing reduced maintenance turfgrass germplasm by completing the DNA sequencing of the Kentucky bluegrass and hard fescue reference genomes. In support of Sub-objective 4B, to determine the extent of Genotype x Environment x Management interactions on reduced maintenance turfgrass performance, work continued on the development of turf-type germplasms of North American and Eurasian wheatgrass with improved aesthetics and performance when grown with reduced irrigation and fertilizer. Evaluations for high levels of turf quality, low plant height, high plant density, and high seed yield potential in experimental wheatgrass populations were completed and seed produced for the next cycle of evaluation and selection. Evaluation of warm-season turfgrass green color retention when grown in cool temperatures continued, with bermudagrass and zoysiagrass germplasm that varied for color retention under cold temperatures being subjected to freezing temperatures, plant tissues sampled, and RNA sequenced. In support of Objective 5, to identify efficient pasture and rangeland-based grazing strategies that simultaneously improve economic and environmental sustainability of livestock production, ARS scientists at Logan, Utah, published a paper that compared four breeds of dairy heifers grazing grass alone or grass-legume mixtures to see if some breeds are more efficient than others when grazing lower or higher quality pastures.

Accomplishments
1. Release of ‘USDA-Yeti’ orchardgrass with increased winterhardiness and high-quality forage production. Orchardgrass is one of the most important perennial grasses used in temperate agriculture for forage or fodder. Among other traits, producers value orchardgrass for its high productivity, nutritive value, and palatability. However, in more northern and higher elevation locations, orchardgrass often suffers from winter injury and mortality. Therefore, ARS researchers in Logan, Utah, started a breeding program to develop a winter-hardy variety. They used persistent plants growing at high elevations in the Intermountain West as parents and traditional plant breeding to select for improved winterhardiness and high agronomic performance. These breeding efforts resulted in the developed of the orchardgrass cultivar USDA-Yeti which combines excellent winterhardiness (10-30% less winter injury), improved stand establishment (12 to 16% greater), and greater forage mass (12-20% more) than other orchardgrass varieties. This combination of traits is not available in other commercially available orchardgrass cultivars. Thus, USDA-Yeti will benefit the livestock and dairy industry by expanding the option of high-quality grass production at sites that are at risk of orchardgrass winter injury or mortality.

2. Release of ‘Destination’ Snake River wheatgrass for improved establishment in restoration of western rangelands. Native grasses, including Discovery and Secar Snake River wheatgrass, are widely used for restoration of rangelands in the Intermountain West that have been negatively impacted by exotic weedy annuals and frequent wildfire. However, their use and effectiveness are limited by low seed yields and poor establishment. To address these limitations, ARS researchers in Logan, Utah, developed ‘Destination’ Snake River wheatgrass through repeated selection for faster deep-seeding emergence and increased seed yield within Discovery Snake River wheatgrass. As a result, Destination has greater biomass (50% more), increased seed yield (24 to 61% better), and improved stand establishment (66% stand versus 34 and 12%, respectively) when compared to the common varieties of Discovery and Secar. Hence, this new and improved variety of Snake River wheatgrass will benefit seed producers, help increase seed inventories, and be a valuable resource to public land managers as it facilitates improved restoration success relative to its predecessors, Discover and Secar.

3. Jersey dairy heifers are efficient pasture grazers. The public prefers pasture grazing for dairy milk production because it reduces manure storage (odor, flies, and water pollution), reduces use of fuel to harvest forages, and improves cow health. However, grazing dairy cows eat less and produce 32% less milk. One way to address this problem, could be to use dairy cows that are better at grazing. Therefore, ARS researchers in Logan, Utah, in collaboration with researchers at Utah State University compared four breeds of dairy heifers grazing grass alone or grass-legume mixtures to see if some breeds are more efficient than others when grazing lower or higher quality pastures. They found that breed rankings for grazing efficiency were the same on both grass and grass-legume mixtures, thus none were better specifically for low- or high-quality pastures. Overall, heifers grazing grass-legume pastures ate 22% more than those grazing grass alone with Holstein’s eating the most. Notably, Jersey heifers were the most efficient at converting grazed feed into growth and thus may be best adapted for pasture grazing. This information will be useful to dairy managers and improve the efficiency and sustainability of pasture-based dairy production.

4. New genomic resources to help understand and combat a troublesome turfgrass weed. Turfgrass is a $40-60 billion industry and with 25-50 million acres is the fourth largest crop in the United States. However, annual bluegrass (Poa annua) is an extremely problematic weed due to its resistance to multiple types of herbicides, wide range of physical characteristics, and its ability to thrive in climates throughout the world. Turf managers spend considerable time and resources trying to control annual bluegrass with little success and the lack of genomic resources have hampered genetic studies to understand why annual bluegrass is so successful as a weed. Therefore, ARS researchers in Logan, Utah, and Beltsville, Maryland, in collaboration with researchers at Pennsylvania State University, Brigham Young University, Utah State University, and Michigan State University sequenced the genomes of annual bluegrass and its evolutionary parents, Poa infirma and Poa supina. They found over 37,000 genes in each genome and even though all three species were genetically similar, differences in parental genomes of annual bluegrass appear to play a central role in its adaptability as a weed. These genome sequences and genes are powerful new tools that will help weed scientists and turfgrass managers learn how to better control annual bluegrass.

U.S. DEPARTMENT OF AGRICULTURE

Forage and Range Research: Logan, UT