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Bromus (Poaceae Bromeae) is a forage grass with high adaptability and ecological and economic value. Here, we sequenced Bromus ciliatus, Bromus benekenii, Bromus riparius, and Bromus rubens chloroplast genomes and compared them with four previously described species. The genome sizes of Bromus species ranged from 136,934 bp (Bromus vulgaris) to 137,189 bp (Bromus ciliates, Bromus biebersteinii), with a typical quadripartite structure. The studied species had 129 genes, consisting of 83 protein-coding, 38 tRNA-coding, and 8 rRNA-coding genes. The highest GC content was found in the inverted repeat (IR) region (43.85–44.15%), followed by the large single-copy (LSC) region (36.25–36.65%) and the small single-copy (SSC) region (32.21–32.46%). There were 33 high-frequency codons, with those ending in A/U accounting for 90.91%. A total of 350 simple sequence repeats (SSRs) were identified, with single-nucleotide repeats being the most common (61.43%). A total of 228 forward and 141 palindromic repeats were identified. No reverse or complementary repeats were detected. The sequence identities of all sequences were very similar, especially with respect to the protein-coding and inverted repeat regions. Seven highly variable regions were detected, which could be used for molecular marker development. The constructed phylogenetic tree indicates that Bromus is a monophyletic taxon closely related to Triticum. This comparative analysis of the chloroplast genome of Bromus provides a scientific basis for species identification and phylogenetic studies. [ABSTRACT FROM AUTHOR]

The effects of fire seasonality and prescribed burning on exotic species invasion are poorly understood in black greasewood (Sarcobatus vermiculatus) plant communities of North America. The impacts of reintroducing fire in the fall and spring on community composition and current-year biomass were evaluated at two such sites, one dominated by exotic annual C3 grasses in Miles City, Montana, USA, and one dominated by native perennial C4 grasses in Laramie, Wyoming, USA. Study sites were assessed based on existing Ecological Site Description (ESD) and State-and-Transition Models (STMs) and the Montana site was determined to be more degraded than the Wyoming site. Experimental design was a randomized complete block design with burns conducted in the fall of 2020 and spring of 2021. Exotic species such as Bromus arvensis were reduced by 56% in spring burned plots the following year and by 25% in the fall burned plots over the course of the study in Montana (58.3–43.5%) and Bromus tectorum did not increase in spring or fall burned plots in Wyoming. Accordingly, the proportion of native species in both plant communities remained constant and native perennial C4 grasses such as Sporobolus airoides were resilient to fire. Moreover, burn treatment had no negative effects on plant species richness, evenness, or diversity in either location. Fire treatments had variable effects on current-year biomass with variable influences of drought and season of burn. Prescribed fire, regardless of season, did not exacerbate exotic plant species spread or reduce native species dominance in either location – suggesting that phreatophytic S. vermiculatus rangelands near the eastern terminus of their range are resilient to anthropogenic burning. Future research should investigate the use of prescribed fire with other methods such as revegetation and herbicide application for reducing exotic plant dominance and increasing native plant species.

Drought is one of the most important abiotic stresses limiting the survival, growth, and productivity of plants in many regions of the world. This study was conducted to evaluate drought tolerance of the recombinant genotypes of two species of orchardgrass and smooth bromegrass based on clonal evaluation and stress tolerance indices. In this study, 36 genotypes selected from polycross populations of both species of orchardgrass and smooth bromegrass were evaluated in terms of phenological, agronomic and morphological traits under normal (50% water depletion from the root zone depth) and drought-stressed (90% water depletion from the root zone depth) conditions during 2013 to 2015 at the Research Farm of Isfahan University of Technology, Isfahan, Iran. To evaluate drought tolerance of the mentioned genotypes, five drought tolerance and susceptibility indices including stress tolerance indices (TOL and STI), mean productivity index (MP), geometric mean productivity (GMP) and stress sensitivity index (SSI) were calculated based on forage yield under drought stress (Ys) and non- stress (Yp) conditions. In both species, high genetic variation was observed among genotypes in terms of most of the studied traits and indices. In orchardgrass, the genetic coefficient of variation varied from 4.31% to 23.5% under normal condition, and from 1.31% to 21.3% under drought stress condition. In smooth bromegrass, the range of genetic coefficient of variation was variable from 2.05-21.4% under normal condition and 1.66-24.6% under drought stress condition. This indicated a high potential for improving these traits through targeted selection in breeding programs of the two species. Drought stress significantly affected most of the studied traits and reduced the genetic variability of traits except for days to ear emergence, days to pollination, percentage of dry matter yield of cut 1, and percentage of dry matter yield of cut 2 in orchardgrass, and percentage of dry matter yield of cut 1 and percentage of dry matter yield of cut 3 in smooth bromegrass. The amount of this reduction for dry matter yield of cuts 1, 2 and 3 was 47.5, 67.3, and 66.6 percent, respectively, in orchardgrass, and 37.4, 49.5, and 49.4 percent, respectively, in smooth bromegrass. Low heritability for forage yield (24.7, 13.5, and 25.9 percent for dry matter yield of cut 1, dry matter yield of cut 2, and dry matter yield of cut 3, respectively, in orchardgrass, and 59.5, 45.9, and 59.4 percent for dry matter yield of cut 1, dry matter yield of cut 2, and dry matter yield of cut 3, respectively, in smooth bromegrass) suggested that direct selection based on forage yield is not effective for the improvement of this trait. Though, indirect selection based on components of forage yield which have high heritability and high correlation with yield (i.e. plant height, stems/plant, and crown diameter in both species), would be more effective. In both species, selection indices of MP, GMP, and STI had a positive and significant correlation with forage yield (0.92, 0.75, and 0.75, respectively, under normal condition, and 0.61, 0.81, and 0.77, respectively, under drought-stressed condition, in orchardgrass; and 0.95, 0.92, and 0.88, respectively, under normal condition, and 0.91, 0.95, and 0.95, respectivel, under drought-stressed condition, in smooth bromegrass). Therefore, these indices were identified as desirable ones in the selection of drought tolerant cultivars in orchardgrass and smooth bromegrass. Based on the results of principal component analysis and drought tolerance and susceptibility indices, the genotypes of 13 and 14 in orchardgrass, and 13 and 32 in smooth bromegrass were identified as superior genotypes in terms of forage yield and drought tolerance. These genotypes can be used as superior parents for the development of genetic populations to improve forage yield and stress tolerance and create synthetic cultivars.

Drought is one of the most important abiotic stresses limiting the survival, growth, and productivity of plants in many regions of the world. This study was conducted to evaluate drought tolerance of the recombinant genotypes of two species of orchardgrass and smooth bromegrass based on clonal evaluation and stress tolerance indices. In this study, 36 genotypes selected from polycross populations of both species of orchardgrass and smooth bromegrass were evaluated in terms of phenological, agronomic and morphological traits under normal (50% water depletion from the root zone depth) and drought-stressed (90% water depletion from the root zone depth) conditions during 2013 to 2015 at the Research Farm of Isfahan University of Technology, Isfahan, Iran. To evaluate drought tolerance of the mentioned genotypes, five drought tolerance and susceptibility indices including stress tolerance indices (TOL and STI), mean productivity index (MP), geometric mean productivity (GMP) and stress sensitivity index (SSI) were calculated based on forage yield under drought stress (Ys) and non- stress (Yp) conditions. In both species, high genetic variation was observed among genotypes in terms of most of the studied traits and indices. In orchardgrass, the genetic coefficient of variation varied from 4.31% to 23.5% under normal condition, and from 1.31% to 21.3% under drought stress condition. In smooth bromegrass, the range of genetic coefficient of variation was variable from 2.05-21.4% under normal condition and 1.66-24.6% under drought stress condition. This indicated a high potential for improving these traits through targeted selection in breeding programs of the two species. Drought stress significantly affected most of the studied traits and reduced the genetic variability of traits except for days to ear emergence, days to pollination, percentage of dry matter yield of cut 1, and percentage of dry matter yield of cut 2 in orchardgrass, and percentage of dry matter yield of cut 1 and percentage of dry matter yield of cut 3 in smooth bromegrass. The amount of this reduction for dry matter yield of cuts 1, 2 and 3 was 47.5, 67.3, and 66.6 percent, respectively, in orchardgrass, and 37.4, 49.5, and 49.4 percent, respectively, in smooth bromegrass. Low heritability for forage yield (24.7, 13.5, and 25.9 percent for dry matter yield of cut 1, dry matter yield of cut 2, and dry matter yield of cut 3, respectively, in orchardgrass, and 59.5, 45.9, and 59.4 percent for dry matter yield of cut 1, dry matter yield of cut 2, and dry matter yield of cut 3, respectively, in smooth bromegrass) suggested that direct selection based on forage yield is not effective for the improvement of this trait. Though, indirect selection based on components of forage yield which have high heritability and high correlation with yield (i.e. plant height, stems/plant, and crown diameter in both species), would be more effective. In both species, selection indices of MP, GMP, and STI had a positive and significant correlation with forage yield (0.92, 0.75, and 0.75, respectively, under normal condition, and 0.61, 0.81, and 0.77, respectively, under drought-stressed condition, in orchardgrass; and 0.95, 0.92, and 0.88, respectively, under normal condition, and 0.91, 0.95, and 0.95, respectivel, under drought-stressed condition, in smooth bromegrass). Therefore, these indices were identified as desirable ones in the selection of drought tolerant cultivars in orchardgrass and smooth bromegrass. Based on the results of principal component analysis and drought tolerance and susceptibility indices, the genotypes of 13 and 14 in orchardgrass, and 13 and 32 in smooth bromegrass were identified as superior genotypes in terms of forage yield and drought tolerance. These genotypes can be used as superior parents for the development of genetic populations to improve forage yield and stress tolerance and create synthetic cultivars. [ABSTRACT FROM AUTHOR]

Invasive annual grasses can promote ecosystem state changes and habitat loss in the American Southwest. Non-native annual grasses such as Bromus spp. and Schismus spp. have invaded the Mojave Desert and degraded habitat through increased fire occurrence, severity, and shifting plant community composition. Thus, it is important to identify and characterize the areas where persistent invasion has occurred, identifying where subsequent habitat degradation has increased. Previous plot and landscape-scale analyses have revealed anthropogenic and biophysical correlates with the establishment and dominance of invasive annual grasses in the Mojave Desert. However, these studies have been limited in spatial and temporal scales. Here we use Landsat imagery validated using an extensive network of plot data to map persistent and productive populations of invasive annual grass, called hot spots, across the entire Mojave Desert ecoregion over 12 years (2009–2020). We also identify important variables for predicting hot spot distribution using the Random Forest algorithm and identifying the most invaded subregions. We identified hot spots in over 5% of the Mojave Desert mostly on the western and eastern edges of the ecoregion, and invasive grasses were detected in over 90% of the Mojave Desert at least once in that time. Across the entire Mojave Desert, our results indicate that soil texture, aspect, winter precipitation, and elevation are the highest-ranking predictive variables of invasive grass hot spots, while anthropogenic variables contributed the least to the accuracy of the predictive model. The total area covered by hot spots varied significantly among subregions of the Mojave Desert. We found that anthropogenic variables became more important in explaining invasive annual establishment and persistence as spatial scale was reduced to the subregional level. Our findings have important implications for informing where land management actions can prioritize reducing invasive annual persistence and promoting restoration efforts. [ABSTRACT FROM AUTHOR]

Bromus (Poaceae Bromeae) is a forage grass with high adaptability and ecological and economic value. Here, we sequenced Bromus ciliatus, Bromus benekenii, Bromus riparius, and Bromus rubens chloroplast genomes and compared them with four previously described species. The genome sizes of Bromus species ranged from 136,934 bp (Bromus vulgaris) to 137,189 bp (Bromus ciliates, Bromus biebersteinii), with a typical quadripartite structure. The studied species had 129 genes, consisting of 83 protein-coding, 38 tRNA-coding, and 8 rRNA-coding genes. The highest GC content was found in the inverted repeat (IR) region (43.85–44.15%), followed by the large single-copy (LSC) region (36.25–36.65%) and the small single-copy (SSC) region (32.21–32.46%). There were 33 high-frequency codons, with those ending in A/U accounting for 90.91%. A total of 350 simple sequence repeats (SSRs) were identified, with single-nucleotide repeats being the most common (61.43%). A total of 228 forward and 141 palindromic repeats were identified. No reverse or complementary repeats were detected. The sequence identities of all sequences were very similar, especially with respect to the protein-coding and inverted repeat regions. Seven highly variable regions were detected, which could be used for molecular marker development. The constructed phylogenetic tree indicates that Bromus is a monophyletic taxon closely related to Triticum. This comparative analysis of the chloroplast genome of Bromus provides a scientific basis for species identification and phylogenetic studies.

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Native bunchgrass communities dominated by Stipa pulchra are widely distributed in California but share dominance with non‐native annual grasses. Restoration of these grasslands focuses on altering the balance of native to non‐native grasses to favor the former. This study investigated the impact of burning on vegetation recovery. In the first postfire year burning showed a 70% reduction in cover of non‐native annual grasses (Bromus diandrus exhibited the greatest reduction) and minimal impact on S. pulchra recovery. In the following 3 years, S. pulchra recovered to levels comparable to controls, whereas the annual grasses remained below control levels until the fifth year. Also, in response to reduced annual grass cover on burned sites several species of non‐native Erodium increased from 10 to 30% relative cover, however, the low growth form of these forbs presented a less competitive threat to bunchgrasses than the non‐native annual grasses, and by the third postfire year returned to near control levels. The rare native geophyte Brodiaea kinkiensis was present throughout these grasslands and was not inhibited by burning treatments. To document the reliability of these patterns a second prescription burn was conducted on these sites 5 years after the first burn and vegetation recovery followed for the subsequent 4 years. Patterns observed after the first burn were duplicated following the second burn. The cover of S. pulchra varied in response to precipitation, with the 95% credible intervals of precipitation parameters overlapping zero, however, the cover of non‐native grasses varied greatly with precipitation and had similar trajectories in unburned and burned plots. [ABSTRACT FROM AUTHOR]

Bromus picoeuropeanus is a recently described species belonging to a complex genus of grasses. It inhabits stony soils at heights ranging from 1600 to 2200 m in Picos de Europa (Cantabrian Mountains, northern Spain). This species is morphologically very similar to B. erectus, partially sharing its presumed distribution range. We aim to determine the relationship between these species and their altitudinal ranges in Picos de Europa and the Cantabrian Mountains by conducting phylogenetic analyses based on nuclear (ETS and ITS) and chloroplastic (trnL) markers. Phylogenetic trees were inferred by Maximum Likelihood and Bayesian Inference. Haplotype networks were estimated based on the plastid marker. Although the ITS topologies could not generate exclusive clades for these species, the ETS analyses generated highly supported B. picoeuropeanus exclusive clades, which included locations outside its altitudinal putative range. The ETS-ITS and ETS-ITS-trnL topologies generated B. picoeuropeanus exclusive clades, whereas the trnL-based trees and haplotype networks were unable to discriminate B. erectus and B. picoeuropeanus. This evidence suggests that B. picoeuropeanus is a separate species with a larger distribution than previously thought, opening new questions regarding the evolution of B. erectus and other similar species in European mountainous systems. However, more information is needed regarding B. picoeuropeanus susceptibility to temperature rises. [ABSTRACT FROM AUTHOR]

Herbicide-resistant weeds currently challenge sustainable food production in almost all cropping systems in Europe. Herbicide resistance is increasing, and some European countries are among the most affected globally, such as Spain and France. This situation is worsening not only due to herbicide use restrictions but also due to climate change, rendering Mediterranean countries such as Spain particularly susceptible. Therefore, focus should be aimed at preventive measures, which include those not only based on integrated weed management strategies but also based on a very good knowledge of the biology and ecology of each weed species. The main objective of this review is to provide an overview of potential future herbicide-resistant cases that can evolve in the near future in Europe. We use Spain as the case study, as it is the most affected country in Europe and because it is at risk due to global warming. For different resistant cases detailed on a crop basis, adequate prevention and management measures will be provided in order to avoid resistance evolution relative to the sites of action that are most likely to generate resistant biotypes due to expected high selection pressures. [ABSTRACT FROM AUTHOR]

A former lectotype for Bromus cincinnatus Ten. (Poaceae) has been superseded, as it is in serious conflict with the protologue. Another element of the protologue has been designated as the effective lectotype. The new lectotype is identified as coespecific with Bromus intermedius Guss., a Mediterranean species of Bromus L. subg. Bromus. The new combination Helictochloa panormitana (Lojac.) Romero Zarco is proposed for the species originally described as Avena australis Parl., nom. illeg., which is currently known as Helictochloa cincinnata auct. The lectotypes of Avena panormitana Lojac., Avena opulenta Lojac., and Bromus intermedius Guss. are also designated.

Invasive annual grasses pose a severe threat to drylands of the United States by increasing habitat degradation and the occurrence and severity of wildfires, while simultaneously outcompeting native species. Advances in technology and accessibility of small uncrewed aerial vehicles (sUAV) provide the opportunity for small preserve managers to map and monitor plant invasions in critical habitats for rare and endemic plant species. Many remote sensing techniques rely on the invasive plants' different phenological signals to distinguish them from native plants and habitats. However, invasive annual grasses in the western United States have high variability of interannual productivity and may not green up each year. Therefore, our objective was to use an sUAV (quadcopter drone) to map invasive annual grass regardless of phenological stage in critical Mojave Desert habitat. The study locations were White Dome, a small habitat preserve, and Beehive Dome in Washington County UT, USA. These areas are critical habitats for several endangered and threatened plant species and are covered with sensitive biological soil crusts, making on-the-ground measurements destructive. Using imagery collected with an sUAV we created red, green, blue (RGB) orthomosaics and calculated the Visible Atmospherically Resistant Index (VARI) across these areas. We successfully mapped the litter of invasive annual grasses at one of the two sites. At White Dome, we attained 95.2 % and 84.3 % Producer's and User's Accuracy in mapping invasive annual grasses based on the RGB spectral signature of invasive grass litter. At Beehive Dome, the heterogeneous nature of the edaphic and topographical features made it difficult to accurately map (

The aim of the study was to evaluate the effect of grazing Lolium perenne (Lp) and Bromus valdivianus (Bv) on the average daily weight gain (ADG) and nitrogen use efficiency (NUE) of Holstein Friesian heifers. Thirty heifers strip-grazed two pasture treatments (Lp and Bv) under a randomized complete block design (n = 3). Nutrient concentration and pasture intake were determined. Urine samples were taken, and the total volume of urine and microbial growth were estimated. Retained nitrogen (N), N intake, N excreted in feces and urine and the nitrogen use efficiency (NUE) were calculated. Lolium perenne showed greater WSC and ME but lower NDF than Bv, whereas crude and soluble protein were unaffected. There were no effects of species on ADG or feed conversion, and DMI was not affected by grass species, or the synthesis of microbial protein and purine derivatives. Ammonia in the rumen, urinary N and total N excreted were greater for heifers grazing Bv. In conclusion, the consumption of forage species did not alter the ADG or NUE of grazing heifers, but N partitioning was modified for heifers grazing Bv, due to the lower WSC/CP ratio compared with Lp. [ABSTRACT FROM AUTHOR]

Invasive weeds threaten the biodiversity and forage productivity of grasslands worldwide. However, management of these weeds is constrained by the practical difficulty of detecting small-scale infestations across large landscapes and by limits in understanding of landscape-scale invasion dynamics, including mechanisms that enable patches to expand, contract, or remain stable. While high-end hyperspectral remote sensing systems can effectively map vegetation cover, these systems are currently too costly and limited in availability for most land managers. We demonstrate application of a more accessible and cost-effective remote sensing approach, based on simple aerial imagery, for quantifying weed cover dynamics over time. In California annual grasslands, the target communities of interest include invasive weedy grasses (Aegilops triuncialis and Elymus caput-medusae) and desirable forage grass species (primarily Avena spp. and Bromus spp.). Detecting invasion of annual grasses into an annual-dominated community is particularly challenging, but we were able to consistently characterize these two communities based on their phenological differences in peak growth and senescence using maximum likelihood supervised classification of imagery acquired twice per year (in mid- and end-of season). This approach permitted us to map weed-dominated cover at a 1-m scale (correctly detecting 93% of weed patches across the landscape) and to evaluate weed cover change over time. We found that weed cover was more pervasive and persistent in management units that had no significant grazing for several years than in those that were grazed, whereas forage cover was more abundant and stable in the grazed units. This application demonstrates the power of this method for assessing fine-scale vegetation transitions across heterogeneous landscapes. It thus provides means for small-scale early detection of invasive species and for testing fundamental questions about landscape dynamics.

Bromus picoeuropeanus is a recently described species belonging to a complex genus of grasses. It inhabits stony soils at heights ranging from 1600 to 2200 m in Picos de Europa (Cantabrian Mountains, northern Spain). This species is morphologically very similar to B. erectus, partially sharing its presumed distribution range. We aim to determine the relationship between these species and their altitudinal ranges in Picos de Europa and the Cantabrian Mountains by conducting phylogenetic analyses based on nuclear (ETS and ITS) and chloroplastic (trnL) markers. Phylogenetic trees were inferred by Maximum Likelihood and Bayesian Inference. Haplotype networks were estimated based on the plastid marker. Although the ITS topologies could not generate exclusive clades for these species, the ETS analyses generated highly supported B. picoeuropeanus exclusive clades, which included locations outside its altitudinal putative range. The ETS-ITS and ETS-ITS-trnL topologies generated B. picoeuropeanus exclusive clades, whereas the trnL-based trees and haplotype networks were unable to discriminate B. erectus and B. picoeuropeanus. This evidence suggests that B. picoeuropeanus is a separate species with a larger distribution than previously thought, opening new questions regarding the evolution of B. erectus and other similar species in European mountainous systems. However, more information is needed regarding B. picoeuropeanus susceptibility to temperature rises.

Woody, evergreen shrublands are the archetypal community in mediterranean‐type ecosystems, and these communities are profoundly changed when they undergo vegetation‐type conversion (VTC) to become annual, herb‐dominated communities. Recently, VTC has occurred throughout southern California chaparral shrublands, likely with changes in important ecosystem functions. The mechanisms that lead to VTC and subsequent changes to ecosystem processes are important to understand as they have regional and global implications for ecosystem services, climate change, land management, and policy. The main drivers of VTC are altered fire regimes, aridity, and anthropogenic disturbance. Some changes to ecosystem function are certain to occur with VTC, but their magnitudes are unclear, whereas other changes are unpredictable. I present two hypotheses: (1) VTC leads to warming that creates a positive feedback promoting additional VTC, and (2) altered nitrogen dynamics create negative feedbacks and promote an alternative stable state in which communities are dominated by herbs. The patterns described for California are mostly relevant to the other mediterranean‐type shrublands of the globe, which are biodiversity hotspots and threatened by VTC. This review examines the extent and causes of VTC, ecosystem effects, and future research priorities. [ABSTRACT FROM AUTHOR]

Herbicide-resistant weeds currently challenge sustainable food production in almost all cropping systems in Europe. Herbicide resistance is increasing, and some European countries are among the most affected globally, such as Spain and France. This situation is worsening not only due to herbicide use restrictions but also due to climate change, rendering Mediterranean countries such as Spain particularly susceptible. Therefore, focus should be aimed at preventive measures, which include those not only based on integrated weed management strategies but also based on a very good knowledge of the biology and ecology of each weed species. The main objective of this review is to provide an overview of potential future herbicide-resistant cases that can evolve in the near future in Europe. We use Spain as the case study, as it is the most affected country in Europe and because it is at risk due to global warming. For different resistant cases detailed on a crop basis, adequate prevention and management measures will be provided in order to avoid resistance evolution relative to the sites of action that are most likely to generate resistant biotypes due to expected high selection pressures.

Japanese brome (Bromus japonicus Thunb.) has been introduced to four continents from its Eurasian origins and has increased during recent decades, particularly in North America. Invasion of this C3 annual grass into rangelands diminishes native plant communities and hinders livestock performance. Control methods have been developed, but have proven short-lived. Japanese brome is positively correlated with plant litter and standing dead material, suggesting management of those components could be important. Objectives for this study were to isolate and quantify the effects of litter and standing dead on Japanese brome utilizing fall defoliation with four different mowing heights (10, 6, 4, or 1 cm) compared to a non-mowed control. Research was conducted on two ecological sites (silty and claypan) with each site consisting of 25 plots (5.5 × 1.6-m). This study was conducted over 4 yr (2013–2017) and fall mowing reduced old dead mass every year except 2016, which followed a severe drought. Spring soil water was not reduced by fall defoliation. Mowing to 1 cm reduced brome biomass by 40% compared to non-mowed plots and brome production was highly dependent on Sep-Oct precipitation. Brome biomass was least in 2015 during a drought and greatest in 2017 following double the median Sep-Oct precipitation. Non-brome biomass was similar across treatments. An 11% reduction in current-year biomass was observed for mowing heights of 10, 6, and 4 cm whereas a 22% reduction was measured for the 1 cm mowing height compared to non-mowed plots. Perennial grass basal cover was similar for 10, 6, and 4 cm mowing heights and greater than that for mowing at 1 cm whereas, no differences were detected between non-mowed plots and any mowing height. Increasing fall defoliation intensity reduced annual bromes while allowing perennial grasses to persist, indicating fall mowing and possibly grazing are viable options for annual brome management.

The aim of the study was to evaluate the effect of grazing Lolium perenne (Lp) and Bromus valdivianus (Bv) on the average daily weight gain (ADG) and nitrogen use efficiency (NUE) of Holstein Friesian heifers. Thirty heifers strip-grazed two pasture treatments (Lp and Bv) under a randomized complete block design (n = 3). Nutrient concentration and pasture intake were determined. Urine samples were taken, and the total volume of urine and microbial growth were estimated. Retained nitrogen (N), N intake, N excreted in feces and urine and the nitrogen use efficiency (NUE) were calculated. Lolium perenne showed greater WSC and ME but lower NDF than Bv, whereas crude and soluble protein were unaffected. There were no effects of species on ADG or feed conversion, and DMI was not affected by grass species, or the synthesis of microbial protein and purine derivatives. Ammonia in the rumen, urinary N and total N excreted were greater for heifers grazing Bv. In conclusion, the consumption of forage species did not alter the ADG or NUE of grazing heifers, but N partitioning was modified for heifers grazing Bv, due to the lower WSC/CP ratio compared with Lp.

Invasion by exotic grasses is degrading dryland ecosystems worldwide and efforts to restore native vegetation in invaded areas have been largely unsuccessful. Control of invasive grasses with herbicide also limits restoration efforts using native seed. In this study, we evaluated two approaches that could allow for the restoration of a native species Pseudoroegneria spicata while reducing an invasive annual grass Bromus tectorum with a herbicide mixture in the sagebrush steppe ecosystem (the United States). We used two methods to protect native seeds from herbicide: activated carbon was applied as a seed coating with the intent of absorbing the herbicide around the seed, and furrows were used to side‐sweep soil sprayed with herbicide away from the planted seed. Our results indicate that imazapic + glyphosate herbicide application had a strong negative effect on the invasive annual grass, reducing B. tectorum cover 91% after 1 year, and 39% after 2 years. Herbicide also had strong negative effects on P. spicata without a carbon‐coating or furrow treatment, reducing seedling emergence 38%, 2‐year plant density 65%, and 2‐year total growth 90%. Both activated carbon seed coatings and furrow treatments limited herbicide effects on P. spicata 2‐year growth, but neither treatment alone mitigated herbicide effects on all life stages. Combining carbon coatings and furrow treatments mitigated harmful herbicide effects on several plant stages (seedling emergence, plant densities, and growth). Our results suggest that combining activated carbon coatings and furrow results in similar establishment of a native perennial as a non‐herbicide seeding and lowers B. tectorum abundance. [ABSTRACT FROM AUTHOR]

Abstract Native saltbush, Atriplex polycarpa, shrub populations are widely diminished and fragmented in the southern San Joaquin Desert of California due to habitat conversion and invasion by exotic annual grasses of mostly Mediterranean origin. The role these grasses play in saltbush population demography is not well understood. We hypothesized that saltbush seedling recruitment and growth is limited by the competitive interactions with exotic grasses, preventing saltbush stands from maintaining their populations and expanding. We predicted that saltbush seedling recruitment would be reduced by (1) light and moisture competition with the grasses; and (2) the physical barrier of grass residual dry matter (RDM) formed during senescence. To test our predictions, we investigated saltbush seedling recruitment under field conditions across six saltbush populations. We examined how variations in edaphic structure and water availability by site may have affected saltbush seedling recruitment and longer‐term population dynamics. In experimental plots where saltbush seeds were sowed, exotic grass RDM reduced saltbush seedling emergence compared to seeds sown in the absence of RDM; competition post‐emergence was not significant. Saltbush seedlings transplanted into the field had lower mortality and less herbivory in invaded grassy habitats compared to seedlings planted in bare zones in between established, mature saltbush shrubs. Edaphic variation and water availability by site were likely key factors affecting the success of both grass invasion and saltbush recruitment. Our results suggest that there is a seed–seedling conflict: Sites favorable for saltbush seedling emergence (minimal grass cover among mature shrubs) are unfavorable for seedling survival due to high herbivory. Conversely, sites favorable for saltbush seedling survival (high grass coverage away from mature shrubs) are unfavorable for seedling emergence. The RDM produced by grasses represents an important stabilizing feedback favoring continued grass dominance.

Native saltbush, Atriplex polycarpa, shrub populations are widely diminished and fragmented in the southern San Joaquin Desert of California due to habitat conversion and invasion by exotic annual grasses of mostly Mediterranean origin. The role these grasses play in saltbush population demography is not well understood. We hypothesized that saltbush seedling recruitment and growth is limited by the competitive interactions with exotic grasses, preventing saltbush stands from maintaining their populations and expanding. We predicted that saltbush seedling recruitment would be reduced by (1) light and moisture competition with the grasses; and (2) the physical barrier of grass residual dry matter (RDM) formed during senescence. To test our predictions, we investigated saltbush seedling recruitment under field conditions across six saltbush populations. We examined how variations in edaphic structure and water availability by site may have affected saltbush seedling recruitment and longer‐term population dynamics. In experimental plots where saltbush seeds were sowed, exotic grass RDM reduced saltbush seedling emergence compared to seeds sown in the absence of RDM; competition post‐emergence was not significant. Saltbush seedlings transplanted into the field had lower mortality and less herbivory in invaded grassy habitats compared to seedlings planted in bare zones in between established, mature saltbush shrubs. Edaphic variation and water availability by site were likely key factors affecting the success of both grass invasion and saltbush recruitment. Our results suggest that there is a seed–seedling conflict: Sites favorable for saltbush seedling emergence (minimal grass cover among mature shrubs) are unfavorable for seedling survival due to high herbivory. Conversely, sites favorable for saltbush seedling survival (high grass coverage away from mature shrubs) are unfavorable for seedling emergence. The RDM produced by grasses represents an important stabilizing feedback favoring continued grass dominance. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal (AM) fungi are the most abundant plant symbiont and a major pathway of carbon sequestration in soils. However, their basic biology, including their activity throughout a 24-h day : night cycle, remains unknown. We employed the in situ Soil Ecosystem Observatory to quantify the rates of diurnal growth, dieback and net productivity of extra-radical AM fungi. AM fungal hyphae showed significantly different rates of growth and dieback over a period of 24 h and paralleled the circadian-driven photosynthetic oscillations observed in plants. The greatest rates (and incidences) of growth and dieback occurred between noon and 18:00 h. Growth and dieback events often occurred simultaneously and were tightly coupled with soil temperature and moisture, suggesting a rapid acclimation of the external phase of AM fungi to the immediate environment. Changes in the environmental conditions and variability of the mycorrhizosphere may alter the diurnal patterns of productivity of AM fungi, thereby modifying soil carbon sequestration, nutrient cycling and host plant success.

Dominant vegetation in many ecosystems is an integral component of structure and habitat. In many drylands, native shrubs function as foundation species that benefit other plants and animals. However, invasive exotic plant species can comprise a significant proportion of the vegetation. In Central California drylands, the facilitative shrub Ephedra californica and the invasive Bromus rubens are widely dispersed and common. Using comprehensive survey data structured by shrub and open gaps for the region, we compared network structure with and without this native shrub canopy and with and without the invasive brome. The presence of the invasive brome profoundly shifted the network measure of centrality in the microsites structured by a shrub canopy (centrality scores increased from 4.3 under shrubs without brome to 6.3, i.e. a relative increase of 42%). This strongly suggests that plant species such as brome can undermine the positive and stabilizing effects of native foundation plant species provided by shrubs in drylands by changing the frequency that the remaining species connect to one another. The net proportion of positive and negative associations was consistent across all microsites (approximately 50% with a total of 14% non-random co-occurrences on average) suggesting that these plant-plant networks are rewired but not more negative. Maintaining resilience in biodiversity thus needs to capitalize on protecting native shrubs whilst also controlling invasive grass species particularly when associated with shrubs., (© 2024. The Author(s).)

Background: Brome grass (Bromus diandrus Roth) is prevalent in the southern and western cropping regions of Australia, where it causes significant economic damage. A targeted herbicide resistance survey was conducted in 2020 by collecting brome grass populations from 40 farms in Western Australia and subjecting these samples to comprehensive herbicide screening. One sample (population 172-20), from a field that had received 12 applications of clethodim over 20 years of continuous cropping, was found to be highly resistant to the acetyl-CoA carboxylase (ACCase)-inhibiting herbicides clethodim and quizalofop, and so the molecular basis of resistance was investigated., Results: All 31 individuals examined from population 172-20 carried the same resistance-endowing point mutation causing an aspartate-to-glycine substitution at position 2078 in the translated ACCase protein sequence. A wild-type susceptible population and the resistant population had similar expression levels of plastidic ACCase genes. The level of resistance to quizalofop, either standalone or in mixture with clethodim, in population 172-20 was lower under cooler growing conditions., Conclusion: Target-site resistance to ACCase-inhibiting herbicides, conferred by one ACCase mutation, was selected in all tested brome plants infesting a field with a history of repeated clethodim use. This mutation appears to have been fixed in the infesting population. Notably, clethodim resistance in this population was not detected by the farmer, and a high future incidence of quizalofop resistance is anticipated. Herbicide resistance testing is essential for the detection of evolving weed resistance issues and to inform effective management strategies. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., (© 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)

Los objetivos de este trabajo fueron evaluar producción forrajera, contenido de proteína, y producción de semilla de líneas experimentales de cebadillas pampeana, criolla e intermedia. Se utilizó como referencia al cultivar Don Lorenzo INTA de cebadilla Intermedia. Se realizaron dos ensayos según un diseño en bloques completos aleatorizados con cuatro repeticiones. En uno se evaluó producción de materia seca y contenido de proteína, y en la otra producción de semilla y peso de mil semillas. Se realizó ANOVA y OMS (p

Karyotypes of five taxa (fourteen populations) of the genus Bromus from different geographic origins is presented: B. scoparius, B. japonicus, B. madritensis, B. rubens and B. tomentellus. The ploidy levels were different. B. scoparius and B. japonicus were found 2n=2x=14, B. madritensis and B. rubens were found 2n=4x=28 and B. tomentellus were found 2n=6x=42. Detailed karyotype analysis allows us to group the different populations and to postulate relationships among them.

Primary production in deserts is limited by soil moisture and N availability, and thus is likely to be influenced by both anthropogenic N deposition and precipitation regimes altered as a consequence of climate change. Invasive annual grasses are particularly responsive to increases in N and water availabilities, which may result in competition with native forb communities. Additionally, conditions favoring increased invasive grass production in arid and semi-arid regions can increase fire risk, negatively impacting woody vegetation that is not adapted to fire. We conducted a seeded garden experiment and a 5-year field fertilization experiment to investigate how winter annual production is altered by increasing N supply under a range of water availabilities. The greatest production of invasive grasses and native forbs in the garden experiment occurred under the highest soil N (inorganic N after fertilization = 2.99 g m−2) and highest watering regime, indicating these species are limited by both water and N. A classification and regression tree (CART) analysis on the multi-year field fertilization study showed that winter annual biomass was primarily limited by November–December precipitation. Biomass exceeded the threshold capable of carrying fire when inorganic soil N availability was at least 3.2 g m−2 in piñon-juniper woodland. Due to water limitation in creosote bush scrub, biomass exceeded the fire threshold only under very wet conditions regardless of soil N status. The CART analyses also revealed that percent cover of invasive grasses and native forbs is primarily dependent on the timing and amount of precipitation and secondarily dependent on soil N and site-specific characteristics. In total, our results indicate that areas of high N deposition will be susceptible to grass invasion, particularly in wet years, potentially reducing native species cover and increasing the risk of fire.

BACKGROUND Anisantha and Bromus spp. are widespread and difficult to control, potentially due to the evolution of herbicide resistance. In this study, UK populations of four brome species have been tested for the early development of resistance to acetolactate synthase (ALS)‐inhibiting herbicides commonly used in their control. RESULTS: Glasshouse assays confirmed reduced sensitivity to ALS‐inhibiting herbicides in single populations of A. diandra, B. commutatus and B. secalinus, and in three populations of A. sterilis. By contrast, all 60 brome populations tested were sensitive to the ACCase‐inhibiting herbicide propaquizafop and glyphosate. Dose–response with two ALS herbicides showed broad‐ranging resistance in the A. diandra, A. sterilis and B. commutatus populations. In the B. commutatus population, this was associated with a point mutation in the ALS enzyme conferring target site resistance (TSR). Additionally, resistant populations of A. sterilis and B. commutatus populations contained enhanced amounts of an orthologue of the glutathione transferase phi (F) class 1 (GSTF1) protein, a functional biomarker of nontarget site resistance (NTSR) in Alopecurus myosuroides. There was further evidence of NTSR as these plants also demonstrated an enhanced capacity to detoxify herbicides. CONCLUSION: This study confirms the evolution of resistance to ALS inhibiting herbicides in brome species in the UK by mechanisms consistent with the evolution of both TSR and NTSR. These findings point to the need for increased vigilance in detecting and mitigating against the evolution of herbicide resistance in brome species in Northern Europe. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Hordeum spp. (barley grass) and Bromus spp. (brome grass) are annual weed species that achieve long‐distance seed dispersal via attachment to sheep, but also lead to sheep carcass damage due to the penetration of seeds into animal tissues. Range expansion of invasive weed populations predicted as a consequence of climate change may be associated with an increase in seed contamination incidence globally. An examination of Australian abattoir data (2006–2012), along with recent weed distribution patterns, indicates carcass contamination was associated with rainfall and abundance of key annual grass weeds, primarily Bromus spp. and Hordeum spp., although other factors may play a contributing role. Significant differences in seed contamination in slaughtered sheep were noted between states and regions, with widespread contamination occurring throughout all agro‐ecological zones. Abattoir, sheep age and sex significantly influenced incidence, with contamination highest in adult males. Incidence increased with mean monthly rainfall, but declined with mean elevation, and significant interactions were noted between mean monthly temperature and state, and between mean elevation and year. Results show the need for vigilant recording of seed injuries in sheep to enhance weed surveillance efforts and effective integrated weed management of contributing annual grass weeds. [ABSTRACT FROM AUTHOR]

This study is concerned with the morphological cladistic analysis of monotypic tribe Bromeae including the genus Bromus. To characterize taxonomic circumscription of the genus, its species and sectional relationships of 39 taxa belonging to 6 sections and 2 outgroups were evaluated. Based on the heuristic search for 26 morphologhical informative characters, Maximum Parsimony approach was used for phylogenetic analyses The data matrix was analyzed by reweighting characters method, rescaled consistency index and retention index. The results obviously indicate the monophyly of the genus Bromus and taxonomic circumscription of its sections but phylognetic relationships of many of the species within each section remain unresolved. The monotypic sect. Nevskiella (lemmas short, 3.5-5 mm long and awns 3-5 times the length of lemmas) is clearly separated from other sections of the genus Bromus. Old world taxa of the perennial sect. Pnigma are more closely related to sect. Ceratochloa. The annual sects. Genea (spikelets cuneiform, broader at top) and Bromus (spikelets ovate, elliptic or lanceolate tapering towards top, lemmas with 1-5(6) awns) are monophyletic. The present cladistic analysis confirms the incorporation of the genus Boissiera (lemmas with 7-9 awns) into the genus Bromus.

Importance: Cheatgrass is one of North America's most problematic invasive species. Invasion by this annual grass alters ecosystem structure and function and has proven very challenging to remove with traditional approaches. Commercially available bioherbicides, like P . fluorescens D7, are applied with the goal of providing lasting control from a single application. However, experimental results suggest that this bioherbicide has limited efficacy under field conditions. Potential explanations for variable efficacy include a failure of this bioherbicide to establish in the soil microbiome. However, to our knowledge, no data exist to support or refute this hypothesis. Here, we use a deep-sequencing approach to better understand the effects of this bioherbicide on the soil microbiome and screen for P. fluorescens at 18 months post-application., Competing Interests: The authors declare no conflict of interest.

Climate change is increasing the frequency and intensity of extreme events like drought and flooding, which threaten to amplify other global change drivers such as species invasion. We investigate the effect of wet and dry extreme precipitation regimes on invasive species' abundances in northern tallgrass prairies. Because soil moisture is a key determinant of prairie composition, theory and evidence suggest drought conditions will hinder invasion, whereas wetter conditions will enhance invasion. To test this hypothesis, we explored the effect of precipitation on invasive plant species abundance from 2010 to 2019 in 25 managed prairies using observations from 267 transects comprising 6675 plots throughout western Minnesota, USA. We estimated how increases in the number of extremely wet or dry months in a year altered overall invasive species abundance and the abundance of the highly invasive grasses Poa pratensis and Bromus inermis. We found that a greater occurrence of abnormally wet months increased invasive species abundance but found mixed evidence that abnormally dry conditions hindered invasion. Further, more moderately wet and dry months reduced native grass abundance. Together, these results suggest that more frequent extremely wet months may intensify invasive dominance and that dry months may not counterbalance these trends. Given the considerable uncertainty still surrounding the interactive effects of climate change and invasion on native plant communities, this research represents an important step toward quantifying the complex influence of precipitation extremes on invasion dynamics in managed ecosystems of critical conservation concern., (© 2023 The Authors. Ecology published by Wiley Periodicals LLC on behalf of The Ecological Society of America.)

The genus of Bromus is one of the most important collection of rangeland plants, which are distributed in a wide range of natural areas of Iran. Interspecific relationships were evaluated in 90 accessions of 18 Bromus species based on 15 ISSR and 15 SCoT primers. SCoT markers separated the accessions better than ISSR marker. In addition, there was a high interspecific diversity between surveying germplasm. The sections of Bromus genus completely separated based on DNA molecular markers. SCoT markers could separate the accessions in each species. The primers of SC5 and SC35 from SCoT marker and UBC861, UBC857 and UBC844 primers from ISSR marker were identified as the best primers in revealing of genetic diversity between accessions. The sections of Ceratochloa, Genea, Pnigma and Bromus were monophyletic and were placed in one cluster. The section Bromus had a direct relationship with section Genea. In other words, section Ceratochloa has a direct relationship with Pnigma. B. tectorum and B. sericeus. B. sterilis had the most distance with other species in section Genea. B. squarrosus and B. japonicus had the most similarity and B. briziformis with B. danthoniae and B. scoparius with B. rechingeri had a moderate relationship in section Bromus. B. tomentosus and B. persicus had the highest similarity and B. riparius with B. biebersteinii and B. tomentellus with B. inermis had a moderate similarity in section Pnigma. [ABSTRACT FROM AUTHOR]

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During our nomenclatural revision of the genus Bromus L. (Poaceae) for Flora Iberica, we found that several names were still untypified: nine names in current use or their basionyms and five synonyms. Typifications are still needed since stabilising the names will facilitate their use. We propose lectotypes for Bromus alopecuros Poir., B. contortus Desf. (and the superfluous B. alopecuroides Poir.), B. benekenii (Lange) Trimen, B. intermedius Guss. subsp. divaricatus Bonnier & Layens, B. molliformis J.Lloyd ex Billot, B. lepidus Holmb., B. lepidus f. lasiolepis Holmb., Bromus subg. Stenobromus (Griseb.) Hack. and Bromus sect. Stenobromus Griseb. Neotypes for B. erectus Huds. and B. ramosus Huds. and an epitype for B. intermedius subsp. divaricatus Bonnier & Layens are proposed. In addition, we identify an isoneotype for B. erectus and isolectotypes for B. lepidus and B. lepidus f. lasiolepis. The area inhabited by the typified taxa includes both Africa and Europe. All the selected types are in agreement with the current use of the names and, thus, our selections contribute to stabilising the nomenclature of the genus Bromus. A discussion is provided to justify the selections. In addition, we typified two supraspecific names B. subg. Stenobromus and B. sect. Stenobromus. Finally, a new section, B. sect. Penicillius Llamas & Acedo, is described. [ABSTRACT FROM AUTHOR]

Background: The prevalent and repeated use of acetyl-coenzyme A carboxylase (ACCase)-inhibiting herbicides for Bromus tectorum L. control in fine fescue (Festuca L. spp) grown for seed has selected ACCase-resistant B. tectorum populations. The objectives of this study were to (1) evaluate the response of nine B. tectorum populations to the ACCase inhibitors clethodim, sethoxydim, fluazifop-P-butyl, and quizalofop-P-ethyl and the acetolactate synthase (ALS) inhibitor sulfosulfuron and (2) characterize the resistance mechanisms., Results: Bromus tectorum populations were confirmed to be resistant to the ACCase-inhibiting herbicides tested. The levels of resistance varied among the populations for clethodim (resistance ratio, RR = 5.1-14.5), sethoxydim (RR = 18.7-44.7), fluazifop-P-butyl (RR = 3.1-40.3), and quizalofop-P-ethyl (RR = 14.5-36). Molecular investigations revealed that the mutations Ile2041Thr and Gly2096Ala were the molecular basis of resistance to the ACCase-inhibiting herbicides. The Gly2096Ala mutation resulted in cross-resistance to the aryloxyphenoxypropionate (APP) herbicides fluazifop-P-butyl and quizalofop-P-ethyl, and the cyclohexanedione (CHD) herbicides clethodim, and sethoxydim, whereas Ile2041Thr mutation resulted in resistance only to the two APP herbicides. All B. tectorum populations were susceptible to sulfosulfuron (RR = 0.3-1.7)., Conclusions: This is the first report of target-site mutations conferring resistance to ACCase-inhibiting herbicides in B. tectorum. The results of this study suggest multiple evolutionary origins of resistance and contribute to understanding the patterns of cross-resistance to ACCase inhibitors associated with different mutations in B. tectorum. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., (© 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)

In part, the enemy release hypothesis of plant invasion posits that generalist herbivores in the non-native ranges of invasive plants will prefer native plants to exotic invaders. However, the extent to which this occurs in natural communities is unclear. Here, I examined the foraging preferences of an important guild of generalist herbivores—granivorous rodents—with respect to seeds from a suite of native and invasive Bromus (“brome”) species at five study sites distributed across ≈ 80,000 km2 of the Great Basin Desert, USA. By examining only congeners, I accounted for a potentially large source of interspecific variation (phylogenetic relatedness). In general, granivorous rodents removed seeds from native bromes at a 23% higher rate than seeds from invasive bromes, suggesting a preference for native species. This preference was not entirely explained by seed size, and patterns of seed removal were consistent across study sites. These findings suggest that invasive bromes in the Great Basin might experience less rodent granivory than native congeners, which is consistent with a key prediction derived from the enemy release hypothesis. [ABSTRACT FROM AUTHOR]

The sustainability of Mediterranean agroecosystems is threatened by several factors, soil erosion being the most important one due to poor management practices. Seeding native grasses for ground cover is an effective practice to protect soil and enhance ecosystem services, but the species to be used should be adapted to the climatic conditions and the particular requirements of each system. Here, we studied seed germination timing of six winter annual grasses: Aegilops triuncialis , Anisantha madritensis , Anisantha rubens , Bromus hordeaceus , Hordeum murinum and Trachynia distachya ; with potential for ground cover in olive groves of the Iberian Peninsula. We conducted germination experiments under eight treatments of constant and alternate temperatures and seven treatments of water potential, and fitted hydro- and thermal-time models to assess possible responses of seed-based populations to regional climate. In all species, recently-harvested seeds showed high germination rates across a wide range of temperatures, while winter-stored seeds were highly tolerant to moisture stress. Our results suggest that environmental conditions rather than dormancy prevent germination of the studied species after dispersal. This germination pattern contrasts with the deep physiological dormancy described for winter annuals in temperate climates and desert regions, indicating a special adaptation of the studied populations for the long dry season in Mediterranean climates. We conclude that the regeneration ecology of these widely-distributed grasses makes them an excellent source of seeds for ground cover in Mediterranean woody crops. [ABSTRACT FROM AUTHOR]