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Breeding Improved Grasses for Semiarid Rangelands
Abstract
Vast areas of semiarid rangelands in western USA are severely degraded and infested with troublesome weeds such as cheatgrass (Bromus tectorum) and medusahead rye (Taeniatherum asperum). Reseeding with appropriate plant materials that are adapted to the site and competitive enough to replace existing undesirable vegetation is often the most plausible way to reclaim such sites. Unfortunately, many of our native grasses are more difficult to establish and are not as competitive with these exotic weedy grasses as their introduced counterparts, including crested and Siberian wheatgrass (Agropyron cristatum, A. desertorum, and A. fragile). Most native grasses did not evolve under intense management or in association with species as competitive as cheatgrass. Genetically improved germplasms and cultivars of native and introduced (naturalized) grasses have been and are being developed by the Forage and Range Research Laboratory (FRRL) of the United States Department of Agriculture-Agricultural Research Service (USDA-ARS) in cooperation with the Utah Agricultural Experiment Station (UAES) and other agencies. These plant materials have demonstrated the potential for increasing the genetic diversity, protecting watersheds and soil resources, and improving the habitat and grazing potential for livestock and wildlife on semiarid rangelands. Research is also in progress at FRRL to develop germplasm and methodology whereby introduced grasses may be used in combination with natives, and in some instances assist in the establishment of native stands. The proper choice of plant materials must be based on objective criteria if we are to protect our lands and natural resources from further degradation.
... Knutson et al. 2014) and identify general patterns among functional groups and plant community types known to differ in resilience potential (Chambers et al. 2014a). In addition, the relative merits and ecological implications of seeding mixes composed of native and non-native species are equally complex (Asay et al. 2003;Knutson et al. 2014). For example, non-native species may establish more rapidly and interfere with the establishment and growth of native species that exhibit less vigorous seedling growth and development (Waldron et al. 2005;Thompson et al. 2006;Nafus et al. 2016). ...
... However, greater performance of non-native species relative to native species is clearly portrayed from our assessment, suggesting that relative differences between these species identified nearly 50 years ago still stand (Hull 1971). It is not clear from our results whether non-native species show greater adaptation to the conditions at restoration sites, but traits exhibited by these species, including high seedling vigor, drought tolerance, rapid growth, and recovery from defoliation are often sought in breeding programs (Asay et al. 2003), and likely contributed to the better performance of non-native species. In contrast, seed enhancement programs for native species have focused less on these traits, but instead typically emphasize selection for seed and seedling traits to overcome seed production bottlenecks and development of plant materials for distinct geographic locations. ...
... Furthermore, B. prostrata and A. cristatum were specifically developed for use into warm/dry temperature/precipitation regimes typical of the lower elevation A. t. ssp. wyomingensis plant communities (Asay et al. 2003;Tilley et al. 2006) where we found notably greater increases in seeded shrubs and grasses compared to the cooler, higher elevation sagebrush communities (i.e. A. t. ssp. vaseyana). ...
Overabundance of woody plants in semiarid ecosystems can degrade understory herbaceous vegetation and often requires shrub reduction and seeding to recover ecosystem services. We used meta‐analysis techniques to assess the effects of fire and mechanical shrub reduction over two post‐treatment timeframes (1‐4 years and 5‐10 years) on changes in cover and frequency of 15 seeded species at 63 restoration sites with high potential for recovery. Compared to mechanical treatments, fire resulted in greater increases in seeded species. Native shrubs did not increase, and forbs generally declined over time; however, large increases in perennial grasses were observed, suggesting that seeding efforts contributed to enhanced understory herbaceous conditions. We found greater increases in a few non‐native species than native species across all treatments, suggesting the possibility that interference among seeded species may have influenced results of this regional assessment. Differences among treatments and species were likely driven by seedbed conditions, which should be carefully considered in restoration planning. Site characteristics also dictated seeded species responses: while forbs showed greater increases in cover over the long term at higher elevation sites considered to be more resilient to disturbance, surprisingly, shrubs and grasses had greater increases in cover and frequency at lower elevation sites where resilience is typically much lower. Further research is needed to understand the causes of forb mortality over time, and to decipher how greater increases of non‐native relative to native seeded species will influence species diversity and successional trajectories of restoration sites.
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... Bieb.] C.A. Mey), a forb that is toxic to sheep, and to increase livestock forage (Miller 1943(Miller , 1956Frischknecht and Harris 1968;Vale 1974). Crested wheatgrass is still seeded after wildfire in former sagebrush communities largely because of its ability to suppress exotic annual grasses (Arredondo et al., 1998;, but also because it is less expensive and establishes better than widely-available commercial varieties of native species, particularly in hotter and drier sagebrush communities (Asay et al., 2003;Pellant and Lysne 2005;Boyd and Davies 2010;James et al., 2012;Davies et al., 2015). Crested wheatgrass has also been seeded to prevent the development of an annual grass-fire cycle and used in green-stripping programs to break up continuous exotic annual grass fuel (Pellant 1994). ...
... This is not surprising as most successful seeding projects in rangelands, including both native and introduced seedings, occur in average to above-average precipitation years (Hardegree et al., 2016). In addition, most of our native perennial species do not compete well with exotic annual grasses, particularly at the seedling stage (Asay et al., 2003). This is associated with the fact that many native species in the sagebrush ecosystem have evolved over millennia within an environment favoring traits that enhance persistence under abiotically variable conditions (e.g., perennial life histories with substantial investment in below ground biomass to maximize resource capture) vs. traits that produce rapid establishment (e.g., high production of viable seeds that reliably and rapidly germinate, emerge, and establish). ...
Exotic annual grasses dominate millions of hectares and increase fire frequency in the sagebrush ecosystem of North America. This devastating invasion is so costly and challenging to revegetate with perennial vegetation that restoration efforts need to be prioritized and strategically implemented. Management needs to break the annual grass-fire cycle and prevent invasion of new areas, while research is needed to improve restoration success. Under current land management and climate regimes, extensive areas will remain annual grasslands, because of their expansiveness and the low probability of transition to perennial dominance. We propose referring to these communities as Intermountain West Annual Grasslands, recognizing that they are a stable state and require different management goals and objectives than perennial-dominated systems. We need to learn to live with annual grasslands, reducing their costs and increasing benefits derived from them, at the same time maintaining landscape-level plant diversity that could allow transition to perennial dominance under future scenarios. To accomplish this task, we propose a framework and research to improve our ability to live with exotic annual grasses in the sagebrush biome.
... three forms, inter-ploidy hybridization is possible (Dewey 1974). All three forms of crested wheatgrass are economically important, and many cultivars have been released in the past (Asay et al. 1995(Asay et al. , 2003Asay and Jensen 1996). ...
... The early grazing of this species shortens the winterfeeding period and provides forage until the later developing native range grasses are ready to graze in early summer (Dwyer and Owens 1984). Since its introduction in North America, crested wheatgrass has provided an excellent source of forage to cattle, sheep, horse and other livestock due to its nutritional properties, and palatability (Ray et al. 1997;Asay et al. 2003;Li et al. 2004). Previous studies have shown that steer weight gains on crested wheatgrass pasture ranged from 0.82 to 1.59 kg day -1 (Hart et al. 1983;Hofmann et al. 1993;Karn et al. 1999). ...
The objectives of this study were to characterize crested wheatgrass (Agropyron cristatum L.) germplasm for plant maturity and associated agronomic characteristics to identify germplasm with late maturity. A field trial was established in July 2014 at Saskatoon, Canada using 45 crested wheatgrass accessions representing materials from 18 countries in a randomized complete block design with four replications. Data were collected for days to heading, plant height, leaf-to-stem ratio, forage dry matter (DM) yield, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and plant vigor score in 2015, 2016 and 2017 at various developmental stages of crested wheatgrass. All measured traits differed significantly (P ≤ 0.05) among the accessions. Later maturing accessions showed positive associations with leaf-to-stem ratio (r = 0.23), NDF (r = 0.16) and ADF (r = 0.18). Forage DM yield was positively correlated with spring vigor (r = 0.77), leaf-to-stem ratio (r = 0.50), plant height (r = 0.56), regrowth (r = 0.67), and ADF (r = 0.11). There was a negative correlation between forage DM yield and CP concentration (r = − 0.23). According to the unweighted pair group method with arithmetic mean and principal component analysis, the 45 crested wheatgrass accessions were grouped into three main clusters according to the agro-morphological and nutritive value data. Selection for late maturity in crested wheatgrass may lead to increase leaf-to-stem ratio and forage DM yield. Information obtained from this study on agro-morphological traits will be useful for future crested wheatgrass breeding in the region.
... belongs to the family Poaceae and the tribe Triticeae. It is a perennial, low-maintenance grass mainly used as forage and is grown worldwide [1,2]. Wheatgrasses are resistant to drought and cold [3][4][5][6], tolerant to environmental stress [7][8][9] and cadmium [10], and moderately tolerant to salinity. ...
Abstract: Crested wheatgrass (Agropyron cristatum), a wild relative of wheat, is an attractive source of genes and alleles for their improvement. Its wider use is hampered by limited knowledge of its complex genome. In this work, individual chromosomes were purified by flow sorting, and DNA shotgun sequencing was performed. The annotation of chromosome-specific sequences characterized the DNA-repeat content and led to the identification of genic sequences. Among them, genic sequences homologous to genes conferring plant disease resistance and involved in plant tolerance to biotic and abiotic stress were identified. Genes belonging to the important groups for breeders involved in different functional categories were found. The analysis of the DNA-repeat content identified a new LTR element, Agrocen, which is enriched in centromeric regions. The colocalization of the element with the centromeric histone H3 variant CENH3 suggested its functional role in the grass centromere.
Finally, 159 polymorphic simple-sequence-repeat (SSR) markers were identified, with 72 of them being chromosome- or chromosome-arm-specific, 16 mapping to more than one chromosome, and 71 mapping to all the Agropyron chromosomes. The markers were used to characterize orthologous relationships between A. cristatum and common wheat that will facilitate the introgression breeding of wheat using A. cristatum.
... This was likely the result of introduced wheatgrasses establishing better and growing faster than locally sourced native bunchgrasses. Introduced wheatgrasses generally establish better than widely available native bunchgrasses (Hull 1974;Asay et al. 2003;Boyd & Davies 2010;). However, to our knowledge, this is the first comparison of seeding introduced wheatgrasses with locally sourced native bunchgrasses. ...
Perennial grasses are often seeded after disturbances to provide ecosystem services and prevent invasive plant dominance. However, there is widespread disagreement over the use of native compared to introduced grasses. In Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & A. Young) communities, introduced wheatgrasses are often seeded after wildfires because they are less expensive, more available, and establish better than widely‐available native species. However, locally‐sourced native bunchgrasses, which likely have adaptations to local conditions, have not been compared to introduced wheatgrasses. We compared drill‐seeding locally‐sourced native bunchgrasses and introduced wheatgrasses after wildfire in frigid Wyoming big sagebrush communities for three years. Seeded native and introduced bunchgrasses both increased bunchgrass abundance and cover, even though precipitation was below average the first year post‐seeding. Seeding introduced wheatgrasses, however, increased bunchgrass cover and abundance more than seeding native bunchgrasses. Seeding introduced wheatgrasses also limited exotic annual grass abundance and cover, but seeding locally‐sourced native bunchgrasses did not. Native bunchgrasses are slow growing, thus may limit exotic annual grasses in time. Alternatively, additional treatments, such as exotic annual grass control, may be needed to improve their success. The establishment of seeded native bunchgrasses in Wyoming big sagebrush in a below‐average precipitation year is a promising result and suggests further research to improve seeded native vegetation success is warranted. The greater establishment of introduced wheatgrasses and their ability to limit exotic annual grasses suggests that successful introduced species may serve as a model for guiding trait selection in native species.
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... To address the need for improved plant materials for revegetation, plant breeders develop improved perennial grass and legume cultivars (Asay et al., 2003). Ongoing variety trials provide evidence of the improvement gains from these efforts and the area of adaptation of the new cultivars (Robins et al., 2007(Robins et al., , 2013. ...
An analysis of biomass and ground cover data collected from six rangeland sites in the Intermountain and Northern Great Plains areas of the United States from 2000 to 2004 was undertaken to characterize the productivity, stability, and resilience of cool‐season perennial grass species. Among the 13 included species, and the 48 cultivars, intermediate wheatgrass [Thinpyrum intermedium (Host) Barkworth & D.R. Dewey], tall wheatgrass [Thinpyrum elongatum (Host) D.R. Dewey], and to a lesser extent crested wheatgrass [Agropryon cristatum (L.) Gaertn. and A. desertorum (Fisch. ex Link) Schult.] possessed the greatest biomass productivity and ground cover. Basin wildrye [Leymus cinereus (Scribn. & Merr.) Á. Löve], thickspike wheatgrass [Elymus lanceolatus (Scribn. & J.G. Sm.) Gould], and bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) Á. Löve] were least productive and stable. There were no differences among species or cultivars for biomass resilience and differences for ground cover resilience were limited. Overall, these three statistics provide an interesting comparison among rangeland species, but more long‐term datasets are necessary for greater inferences and more definitive conclusions.
... Bluebunch wheatgrass is a C 3 , perennial Triticeae bunchgrass species that occurs throughout the North American Intermountain West and is commonly included in restoration seed mixes in the region (Monsen et al., 2004). Although considerable resources have been devoted to developing more effective plant materials of BBWG (Asay et al., 2003;St. Clair et al., 2013;Gibson and Nelson, 2017), individual plant materials might be better matched to target environments if the ecological implications of seed mass were better understood. ...
To better match plant materials to ecological sites for the purpose of rangeland seedling establishment, we examined the relationship between seed size and growth and morphological traits in young seedlings of bluebunch wheatgrass (BBWG) (Pseudoroegneria spicata [Pursh.] Á. Löve), a perennial Triticeae bunchgrass native to the Intermountain West. Traits examined included onset of germination, seedling biomass traits, and seedling surface-area traits. We grew seeds of nine BBWG populations that varied for seed size and were produced in a common environment under 2 contrasting d/n temperature regimes (20/15°C; 10/5°C). Lighter-seeded populations germinated and initiated shoots earlier. Heavier-seeded populations displayed high levels of biomass-related traits (e.g., shoot and root biomass and shoot length), while lighter-seeded populations displayed high levels of surface area − related traits (e.g., specific leaf area and specific root length [SRL]). Correlations between seed size and young-seedling traits were mostly similar under the two temperature regimes. However, root length − related traits showed more positive correlations with seed size under the low-temperature regime, which is more similar to actual field-emergence conditions during early spring. P-24, a light-seeded population, originated from the most arid site and exhibited the highest SRL at low temperature, while T-17t, a heavy-seeded population, originated from the most mesic site and exhibited moderate SRL. Three populations used for rangeland revegetation, “Whitmar,” “Goldar,” and Anatone Germplasm, all exhibited low seed mass and high SRL. However, only Anatone displayed high root-to-shoot length ratio under both temperature regimes, perhaps explaining its wide and successful use in rangeland seedings.
In this chapter, we summarize the ecology and conservation issues affecting greater (Centrocercus urophasianus) and Gunnison (C. minimus) sage-grouse, iconic and obligate species of rangelands in the sagebrush (Artemisia spp.) biome in western North America. Greater sage-grouse are noted for their ability to migrate, whereas Gunnison sage-grouse localize near leks year-round. Seasonal habitats include breeding habitat where males display at communal leks, nesting habitat composed of dense sagebrush and herbaceous plants to conceal nests, mesic summer habitats where broods are reared, and winter habitat, characterized by access to sagebrush for cover and forage. While two-thirds of sage-grouse habitat occurs on public lands, private land conservation is the focus of national groups including the USDA-NRCS Sage-Grouse Initiative. Sage-grouse are a species of great conservation concern due to population declines associated with loss and fragmentation of more than half of the sagebrush biome. Wildlife and land management agencies have been increasingly proactive in monitoring trends in sage-grouse populations (e.g., lek count index), adapting regulations to reduce harvest on declining populations, and in designing and implementing conservation policies such as core areas to conserve sage-grouse habitats and populations. Much of the remaining sagebrush habitat is threatened by altered fire regimes, invasive annual grasses and noxious weeds, encroaching piñon (Pinus edulis and monophylla)-juniper (Juniperus spp.) woodlands, sagebrush conversion, anthropogenic development, and climate change. Several diseases affect sage-grouse, but to date, disease has not been a widespread cause of declines. Proper livestock grazing and limited hunting appear to be sustainable with sage-grouse, whereas improper grazing, increasing free-roaming equid populations, and sagebrush conversion are primary concerns for future conservation. Research has identified additional concerns for sage-grouse including effects from fence collisions, predation from common ravens (Corvus corax), and reduced habitat effectiveness resulting from grouse avoidance of anthropogenic infrastructure. There is a need for future research evaluating sage-grouse habitat restoration practices following improper rangeland management, habitat alteration from invasive species and fire, effects on small and isolated populations, and effects from diseases.Keywords
Centrocercus urophasianus
Centrocercus minimus
Ecosystem threatsGreater sage-grouseGunnison sage-grousePrivate and public land conservationRangeland managementSagebrush
Weedy species invasions are a huge problem in rangeland and natural areas as they degrade the quality and quantity of forage for livestock and reduce biodiversity. Weed suppression using native grasses is an ecologically driven method of weed management, representing an opportunity for low-input and management over long temporal scales if these systems can be successfully established. A systemic literature review was conducted to explore the interactions between native grasses and weeds, and revealed the potential of native grasses to provide a reduction in weed presence through interactions with other biological communities. We proposed the merging of agronomic and breeding techniques with restoration efforts such as using specialized seeding techniques to establish native grasses in these systems. A generalized planning framework for land managers is also presented, emphasizing the consideration of functional traits for competitive advantage against weeds and germplasm availability as the main considerations for species selection. Management strategies that provide advantages to native grasses such as land clearance and strategic disturbances were also discussed. Suppression can occur through a variety of mechanisms including direct competition with weeds, indirect interactions through trophic levels of arthropods and grazers, and human-induced disturbances. From our results, we believe that native grasses can potentially play an important role in efficacious weed suppression if utilized tactfully.
On the Ground
•The accidental and subsequent invasion of cheatgrass throughout millions of hectares of Intermountain West rangelands has truncated secondary succession by providing a fine-textured, early maturing fuel that has increased the chance, rate, spread, and season of wildfire.
•The restoration or rehabilitation of degraded rangelands throughout the Intermountain West is very challenging due to annual invasive species that exhibit high growth rates and seed production.
•The use of the pre-emergent herbicide, imazapic, decreased cheatgrass densities >95% during the fallow year and before sowing seed the following fall during this study, which significantly reduced the cheatgrass competition for seedlings of seeded species.
•Seed mix performances were significantly higher in herbicide-treated plots than control plots for both sites for both years. Native, introduced, and native/introduced seed mixes were significantly more successful in the treated plots at the Bedell Flat site compared with the Antelope site for both years.
•Cheatgrass densities were significantly higher in the control plots at both sites for both years compared with herbicide/seed mix-treated plots.
•Success and failure of establishing perennial grasses in restoration or rehabilitation practices is highly dependent on proper seed and seed mix selections, seeding methodologies, and rates as well as favorable precipitation.
Includes more than 20,000 entries (about one third are multiple listings under more than one classification). It is limited to North American literature on range management with special emphasis on the US and Canada though an attempt has also been made to cover English language literature of Mexico. The classification system is in 10 primary categories with about 150 sub-categories at three lower levels. -from WAERSA
Experiments were conducted on four semiarid range sites to compare stand establishment, productivity, and persistence of several introduced perennial Triticeae grasses with that of their native counterparts. On Intermountain sites with severe water limitations (< 300 mm), native grasses were more difficult to establish, less productive, and less persistent than the introduced grasses. Stands of native grasses declined most rapidly under defoliation. At locations where moisture conditions were more favorable, particularly where more summer precipitation occurred, native Triticeae grasses established and persisted relatively well compared with the introduced entries. Although difficult to establish, stands of the rhizomatous native, western wheatgrass [Pascopyrum smithii (Rydb.) A. Löve] increased during the seasons after establishment. Choice of plant materials to be used in range seeding programs should be based on objective criteria. To do otherwise will perpetuate degradation of soil resources, especially on sites that are dominated by weedy annual species such as cheatgrass (Bromus tectorum) and medusahead rye (Taeniatherum asperum). It is proposed that adapted introduced grasses be equally considered along with native grasses as a component of seed mixtures on environmentally harsh sites that have been burned, infested with competitive weedy species, or otherwise degraded.
This study reports on the poor performance of selected native grass species compared to that of certain adapted introduced and domesticated grasses. Of 12 grass species native to Canada and northern U.S.A., 7 showed very poor initial establishment. Subsequent winterkilling eliminated them. Of the 5 surviving native grass species only 2 attained a fair forage yield level compared to those of 5 domesticated grasses, and then only after the 3rd or 4th years of age. Most of the native species showed limited competition with weeds. Nutrient content, particularly crude protein, of the native grasses was not sustained as well as that in some of the tame grasses with advancing seasonal growth stages.
Twelve strains of native grasses which had undergone selection prior to testing were compared with three introduced grasses under the same management system. On the basis of the 5-yr mean D M yield, crested wheatgrass and meadow bromegrass produced 79% more forage than the native species. Crested wheatgrass and intermediate wheat-grass produced 167% more seed on average than other species. The native species, especially slender wheatgrass and awned wheatgrass suffered considerable winter injury and winter killing. This study supports the belief that most native grasses are shortlived and low-yielding compared to introduced species and that breeders should concentrate their efforts on the introduced species which have an inheritantly higher yield potential.Key words: native grasses, introduced grasses, Agropyron, Bromus, Elymus, Thinopyrum, winter killing, breeding
The six-rowed spring barley (Hordeum vulgare L.) germ plasm line 6NDRFG-1 (Reg. no. GP-136, PI 615583) was developed by the North Dakota Agricultural Experiment Station and tested as C95-167-250-9. 6NDRFG-1 has partial resistance to Fusarium head blight (FHB) (incited by Fusarium graminearum Schw.) that is expressed as reduced numbers of FHB infected kernels and more significantly as reduced concentrations of the mycotoxin deoxynivalenol (DON). 6NDRFG-1 is an F3:7 selection from the cross ‘Foster’/CIho 4196. Foster (PI 592758) (Horsley et al., 1997) is a six-rowed malting barley susceptible to FHB and adapted for growth in the upper Mid-west USA. CIho 4196 is an FHB resistant two-rowed accession received from China in 1925 and held in the USDA National Small Grains Collection. 6NDRFG-1 has a sessile six-rowed spike (vvII ), semi-smooth lemma awns, and glume awn length equal to the length of the glume. Its covered kernels have long rachilla hairs and a white aleurone. Unlike many of the six-rowed genotypes with good FHB resistance, 6NDRFG-1 does not derive its resistance from‘Chevron’ (PI 38061) or Chevron-derived lines (Prom et al., 1996). This may be advantageous because Chevron and resistant Chevron-derived progeny generally have fewer plump kernels and lower malt extract (Gebhardt et al., 1992). Thus, 6NDRFG-1 represents a six-rowed source of FHB resistance that may have alleles for acceptable malt quality not found in Chevron.