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

2022 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 a valuable native grass to survive and flourish under changing conditions associated with weeds, wildfire, and climate change. Studies to identify bluebunch wheatgrass populations with distinct temperature growth profiles were completed through a robust series of seedling–growth experiments conducted under low (5 degrees C) and high (25 degrees C) temperatures. Over 1000 half-sib families (HSF) were evaluated in growth chambers, greenhouse experiments, and a novel seedling growth robot to capture root development rates. Studies to determine the ability of bluebunch wheatgrass populations to adapt to changing soil moisture and nutrients were completed through a series of greenhouse experiments. Over 1000 HSF were screened for seedling emergence rate, seedling height and tiller number after 14 and 28-days of exposure to either drought conditions or elevated soil nutrients. In addition, seedlings were evaluated for growth and morphological traits, including root development and leaf area. Collaborations with researchers at Burns, Oregon, were initiated by hiring a shared post-doctoral associate and starting growth chamber experiments to further characterize resource capture strategies and seedling establishment rates. Data from all experiments have been combined to accommodate ongoing statistical analyses to identify bluebunch wheatgrass populations with distinct resource capture strategies and narrow or broad adaptation to varying environments, and to determine potential tradeoffs between coping with stress versus when growing in ideal environments. 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, an irrigation study with meadow fescue pasture grass was completed. Preliminary analysis indicated that there was variation for growth under reduced irrigation, but that endophytes in the grass did not confer additional drought tolerance. Research continued comparing the genetic and physiological mechanisms of salt and drought stress tolerance in cool-season turfgrass species. A salt evaluation was completed and published for Kentucky bluegrass, perennial ryegrass, and alkaligrass, and field-based and greenhouse-based drought evaluations were completed with gene expression quantifications made using RNA technology (i.e., RNAseq). 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. Orchardgrass and timothy plants with superior drought tolerance or winterhardiness were selected from two evaluation nurseries and then moved to crossing blocks in Logan, Utah. Alfalfa plants with superior tolerance to salty soils and with high forage production were identified and crossed together, and the harvested seed ready to be used for subsequent evaluation. In addition, an experimental alfalfa with improved drought tolerance and persistence was established in multiple locations for testing, including one test under cattle grazing. 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. A genomic selection model for seedling establishment and plant persistence traits was advanced with the bluebunch wheatgrass training population evaluated for seedling establishment traits and combined with data from other experiments to make genomic predictions. The model was used to identify those plants with superior breeding values for seedling establishment and seed production traits. A foundation seed field of Utah sweetvetch, a new variety with improved seed production, dry matter yield and persistence, was established which will enable large quantities of commercial seed production. Research continued towards development of basalt milkvetch and salina wildrye plant materials, with a salina wildrye breeding nursery established from deep-seeded selections made in the greenhouse. However, seed increase of basalt milkvetch failed due to insufficient pod development and will be attempted again next year. Also, research continued in development of non-shattering creeping wildrye with non-shattering plants identified and allowed to intermate. 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 long-term seed-mixture rangeland plots. The pre-germination seed treatments necessary for improved seedling emergence of the native legume, Utah trefoil, were identified. Experiments to characterize the rate of root development of bottlebrush squirreltail and Sandberg’s bluegrass varieties were completed using novel, glass-sided growing plates, wherein digital images of roots were acquired over five weeks. Three of these evaluations evaluated how root development is affected by reduced water conditions and consecutive drought intervals. Water extraction rates of each variety were evaluated under increasing seedling density using large volume lysimeters that tracked changes due to seedling evaporation. In addition, emergence rates of bottlebrush squirreltail and Sandberg’s bluegrass under variable seedbed temperatures and under various soil nutrient conditions were evaluated in growth chambers and in potted plants. The datasets were combined to evaluate the correlations among seedling root traits and first- and second-year seedling establishment. In support of Objective 3, ARS scientists at Logan, Utah, continued to develop new plant materials with improved nutritive value and forage productivity. Morphological data in support of a putative tall fescue cultivar release was completed. Development of perennial ryegrass with increased cell wall digestibility continued with the breeding population phenotyped for fiber digestibility, and novel DNA-trait association analysis conducted with thousands of single nucleotide polymorphism (SNP) DNA markers. The development of orchardgrass with increased water-soluble carbohydrate concentration started again (COVID-related delays) with an evaluation in Logan, Utah, of experimental lines from multiple countries. In support of developing a genomic selection model for forage and grain production traits in intermediate wheatgrass, families of the training population were evaluated for grain yield over a period of two years. Results were combined with data from other experiments to make genomic predictions for these traits and those intermediate wheatgrass plants with superior breeding values (i.e., 100 plants) for seed production identified. In support of Sub-objective 4A, ARS scientists at Logan, Utah, continued to identify genetic methods that improve the efficiency of developing reduced maintenance turfgrass germplasm. Kentucky bluegrass and hard fescue genomes were sequenced, and functional molecular markers developed to augment breeding for reduced-maintenance turf. Additional genotyping and association analysis within hard fescue was initiated. 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 germplasm 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 populations of North American and Eurasian wheatgrasses was completed. In addition, research continued the evaluation of warm-season turfgrass germplasm green color retention when grown in cool temperatures. A re-evaluation of the populations with the highest and lowest color retention was completed and gene expression quantifications initiated using RNA technology (i.e., RNAseq). 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 papers reporting that dairy cattle eat more and have better growth performance when grazing pastures containing mixtures of high-energy grass and the legume birdsfoot trefoil compared to grass only pastures.

Accomplishments
1. Newly discovered seed germination requirements make Utah trefoil a viable forb for rangeland restoration. Flowering forb species diversify plant communities and sustain pollinators in the intermountain West. However, there is a problematic lack of native forbs and associated planting “know-how” available for their successful use in rangeland restoration efforts. Utah trefoil is a native flowering legume and potential restoration forb candidate, but little was known about its seed germination requirements. ARS researchers at Logan, Utah, determined that Utah trefoil seed was largely dormant requiring both acid and cold pre-treatments for successful germination. While neither pre-treatment was effective alone, combined they increased seed germination from less than 1% (untreated) to 73%. Furthermore, seedling establishment in the field was 50 times greater using the combined pre-treatments compared to untreated seed. With this new knowledge available to the seed industry and land managers, Utah trefoil now has the potential to become a valuable and viable native forb for rangeland seedings.

2. Release of ‘Basin’ Utah sweetvetch with improved seed production. The inclusion of flowering forb species in rangeland restoration helps to diversify plant communities and sustain pollinators. As such, Utah sweetvetch is a native perennial legume often sought for rangeland seedings, but its use has been severely limited due to low seed production and resulting insufficient seed inventories. ARS researchers at Logan, Utah, were able to develop Utah sweetvetch plants with increased seed production using traditional plant breeding to repeatedly (three times) select and hybridize plants with high seed set. This resulted in the release of ‘Basin’ Utah sweetvetch which has greater than double (682 versus 320 kg/ha) the seed production of previously available cultivars. Furthermore, Basin Utah sweetvetch has improved forage production – a trait important for wildlife like deer and elk. This new improved cultivar of Utah sweetvetch will benefit seed producers, help increase seed inventories, and be a valuable resource for land managers desperately seeking viable flowering forb options for rangeland seedings in the western United States.

U.S. DEPARTMENT OF AGRICULTURE

Forage and Range Research: Logan, UT