Smooth Bromegrass Research Articles

Agroecological importance of smooth brome in managing wheat stem sawfly (Hymenoptera: Cephidae) via associated braconid parasitoids.

Wheat stem sawfly (WSS), Cephus cinctus Norton (Hymenoptera: Cephidae), is a major pest of cereal crops throughout the Northern Great Plains of North America. Native parasitoids, Bracon cephi (Gahan) and B. lissogaster Muesebeck (Hymenoptera: Braconidae), play a key role in suppressing WSS populations and limiting associated damage. Smooth brome grass (Bromus inermis Leyss.) serves as a potential trap reservoir for WSS when grown in areas surrounding wheat (Triticum aestivum L.) fields in Montana. Its unique biology allows it to support high WSS infestation while promoting significant larval mortality throughout the growing season. Late-season WSS survivors can then serve as hosts for WSS parasitoids. Our study investigated smooth brome as a host refuge for WSS parasitoids. We measured WSS larval infestation and survival rate inside smooth brome grown within WSS-inclusion cages, finding a maximum infestation of 66.5% and an end-of-year WSS survival of 5.7%. In addition, we collected stems from sites in central and north-central Montana to measure the WSS infestation and parasitoid prevalence in wheat and adjacent smooth brome. WSS infestation was high in both Big Sandy (64.5% smooth brome, 65.7% adjacent wheat) and Moccasin, MT (50.6%, 38.6%). Year-end WSS larval mortality was 43.6% greater in smooth brome compared to adjacent wheat at both field sites, but both hosted similar numbers of WSS parasitoids. This research underscores the importance of smooth brome in providing a sustainable host refuge for WSS parasitoids and highlights its significant role in supporting the economics of wheat cultivation.

The LTAR Grazing Land Common Experiment at Platte River High Plains Aquifer.

The Long-Term Agroecosystem Research (LTAR) network of the United States Department of Agriculture (USDA) consists presently of 18 sites within the contiguous United States that are managed by the Agricultural Research Service (ARS) and its partners. The LTAR network focuses on developing national strategies for more efficient, resilient, and profitable agricultural production systems, improved environmental quality, and enhanced rural prosperity. The Platte River High Plains Aquifer (PRHPA) LTAR site is managed jointly by the University of Nebraska-Lincoln (UNL) and USDA-ARS and is one of the LTAR sites that conduct research on both integrated cropping and grazing systems. The PRHPA region encompasses multiple land resource areas and diverse agricultural production systems. The PRHPA sites, predominantly located in eastern Nebraska, are designated as an integrated system focused specifically on the region's dominant production practices of row crop (corn and soybean), managed pastures, and beef cattle production. Here, we focus on C3 cool-season smooth bromegrass (Bromus inermis Leyss.) pasture grazing systems under prevailing and alternative management practices for the region. The sites evaluate continuous and rotational grazing with and without pasture fertilization (prevailing practices). In an additional treatment, cattle are supplemented with dry distillers grains plus solubles, while manure supplies fertilization (alternative practice). Main measurements at the site evaluate plant and animal productivity, forage quality, greenhouse gas fluxes, and soil physical, chemical, and biological properties. This paper describes the regional characteristics of the PRHPA site, ongoing LTAR research related to pasture and livestock production, stakeholder engagement, and future research plans.

Selection environment impacts genetic gains for persistence in three temperate perennial forage grasses

Grasses and legumes are regularly grown in association, despite often being unbalanced or incompatible. This study was intended to conduct selection for persistence in three perennial grass species that have compatibility issues with alfalfa (Medicago sativa L.) or red clover (Trifolium pratense L.) and are poorly adapted to management-intensive rotational grazing. Five cycles of selection for persistence were conducted over a 24-year period for three grass species (reed canarygrass, smooth bromegrass, and timothy) in each of five selection environments: alfalfa mixture, red clover mixture, monocultures with a three-harvest hay management, tall fescue mixture with frequent defoliation, and monocultures with frequent defoliation. Selection in the two legume mixtures led to significant increases in persistence only when evaluated in legume mixtures. Selection responses were strongest when evaluated under the same legume as in the selection environment, indicating some species specificity. Selection for persistence under frequent defoliation was successful under both conditions (monoculture and tall fescue mixture), but led to no changes when evaluated with legumes. For these three grass species, cultivar development for use in mixture with legumes or for use in management-intensive rotational grazing should be based on a selection environment that mimics, as close as possible, the target production environment.

First Report of Alternaria alternata Causing Leaf Spot on Smooth Bromegrass (Bromus inermis Leyss.) in China.

Smooth bromegrass (Bromus inermis Leyss.) is an important forage crop in northern China. In July 2021, leaf spot symptoms were observed on smooth bromegrass in Ewenki Banner, Hulunbuir, Inner Mongolia. In an area of approximately 0.12 hectares, 95% disease incidence was observed. Ten diseased plants were collected for pathogen isolation. Leaf tissues near the lesions were cut into 5 × 5 mm pieces, surface-disinfested in 75% ethanol for 3 min, and rinsed with sterile distilled water. The pieces were placed on water agar in petri plates and incubated at 25℃ for three days. The resulting colonies were flushed with sterile water and a spore suspension was serially diluted and plated on potato dextrose agar (PDA). A single-spore colony was obtained. Ten isolates were obtained and designated HE1 to HE10. The colony morphology was identical for all isolates, grayish white in color on the upper surface and light black on the underside. The mycelia were light gray and velvety. Conidia were light brown to brown in color and oblate, oblong or oval. The conidial dimensions were typically between 15 to 43 μm by 8 to 9 μm in size. The conidia possessed one to six transverse septa, with slight to distinct constrictions at each division, and zero to two longitudinal septa. These morphological characteristics resembled Alternaria alternata (Fr.) Keissl.. DNA was extracted from three isolates, HE3, HE4 and HE5, using the CTAB method. Polymerase chain reaction (PCR) was performed on the extracted DNA with a set of primers ITS1/ITS4, H31a/H31b, gpd1/gpd2, TEF1-728F/TEF1-986R, and RPB2-5F2/fRPB2-7cR. The amplicon sequences from the three isolates were analyzed using the BLAST in GenBank (https://www.ncbi.nlm.nih.gov/). The results showed a high sequence identity, ranging from 99 to 100%, with the A. alternata strain YTMZ-20-2 across all the genetic markers tested. The strong match reinforced the identification of the strains as A. alternata. The sequences were deposited in GenBank (Table S1). The three fungal isolates were identified as A. alternata based on their morphological and genetic data. To conduct Koch's postulates, the representative isolate HE4 was used. Smooth bromegrass seed was soaked in water for four days and sown in potting soil contained in plastic pots (10 cm diameter × 15 cm height, five seeds/pot) in a greenhouse under a 16-h photoperiod at temperatures between 20 to 25°C and 60% relative humidity. When the plants reached a height of approximately 20 cm, the plants in three pots (replicates) were sprayed with a spore suspension (106 conidial/ml) at 10 ml/pot, and three pots were sprayed with sterile water for control. Five days after inoculation, the plants exhibited leaf spot symptoms similar to those previously described, while the control plants remained unaffected. The causative fungus was successfully re-isolated from the diseased plants and confirmed morphologically and molecularly on its identity as described above. This experiment was independently conducted three times. This is the first report of A. alternata causing leaf spot on smooth bromegrass in China. Since there is risk that the disease could seriously reduce the yield of the forage crop smooth bromegrass, further research is needed.

Evaluating Fecal DNA Metabarcoding to Estimate the Dietary Botanical Composition of Goats

Improved techniques are needed to estimate the dietary species composition of grazing animals. The fecal DNA metabarcoding technique has been proposed as a noninvasive method to determine dietary species composition. However, studies suggest that it is more effective to qualitatively estimate species composition of wild and domestic animals than for accurately quantifying diet composition. The technique, using the trnL barcode, was evaluated with 10 individually penned goats, which were fed hand-harvested plant materials that were collected fresh each morning before known amounts of each type of plant materials were fed and completely consumed by the goats. Goats were fed at 3% of their body weight on a DM basis. Broadleaf plant materials fed were Russian olive (Elaeagnus angustifolia), silver buffaloberry (Shepherdia argentea), western snowberry (Symphoricarpos occidentalis), and wormwood sage (Artemisia absinthium) plus a mixture of predominantly smooth bromegrass (Bromus inermis), which also included small amounts of other grasses such as Kentucky bluegrass (Poa pratensis) and forbs such as leafy spurge (Euphorbia esula). Estimates of the dietary composition of the goats were different (P ≤ 0.04) from those of their known dietary composition, except for wormwood sage when expressed on a crude protein basis (P = 0.98), regardless of whether known composition was expressed on a dry matter or crude protein basis. Therefore, we conclude that the fecal DNA metabarcoding technique for estimating the dietary composition of goat diets is useful qualitatively but needs further development to be a better quantitative technique.

Modeling net ecosystem exchange of CO2 with gated recurrent unit neural networks

The complex forcing mechanisms of biophysical drivers on ecosystem productivity, as well as some unknown relationships, stipulates the application of artificial intelligence techniques in modeling the ecosystem carbon cycle. In particular, various deep learning algorithms have been successfully applied to comprehend temporal relationships, though some issues regarding capturing temporal features for modeling CO2 fluxes across time scales remain unsolved. In this study, a gated recurrent unit (GRU) model was trained for simulating half-hourly net ecosystem exchange of CO2 (NEE) using 12-year continuous flux data (2009–2020) from seven experimental bioenergy crops in southwest Michigan, USA. The fields were historically managed either as corn-soybean rotation agricultural (AGR) or Conservation Reserve Program (CRP) lands and planted to no-till corn (AGR-C and CRP-C), restored-prairie (AGR-Pr and CPR-Pr), switchgrass (AGR-Sw and CRP-Sw) and smooth brome grass (CRP-Ref). We compared NEE simulations for the entire year, growing season, and non-growing season datasets, and analyzed relative importance of biophysical variables on variations of NEE. GRU performed well in simulating NEE at single site, with R2 of 0.89–0.93, 0.85–0.90, and 0.61–0.85 for the annual, growing season, and non-growing season datasets, respectively, which provided comparable accuracy and 6 % of run-time shorter than those of long short-term memory. R2 reached 0.70 and 0.80 across all sites and unique land-cover types. Radiation parameters contributed most to the variability of NEE. Contributions of individual variables appear more complex during the non-growing season and include incoming shortwave radiation, day of year, temperature, Monin-Obukhov stability, wind direction, and soil water content. The six most important forcing variables are consistent with our current understanding, although their ranked importance varied by ecosystem type and modeling scale. These results bring renewed insights in modeling observations at seasonal scales and provide guidance for variable selection to scale up measurements from one site to multiple land-cover types across the landscape.

Using Machine Learning Methods Combined with Vegetation Indices and Growth Indicators to Predict Seed Yield of Bromus inermis.

Smooth bromegrass (Bromus inermis) is a perennial, high-quality forage grass. However, its seed yield is influenced by agronomic practices, climatic conditions, and the growing year. The rapid and effective prediction of seed yield can assist growers in making informed production decisions and reducing agricultural risks. Our field trial design followed a completely randomized block design with four blocks and three nitrogen levels (0, 100, and 200 kg·N·ha-1) during 2022 and 2023. Data on the remote vegetation index (RVI), the normalized difference vegetation index (NDVI), the leaf nitrogen content (LNC), and the leaf area index (LAI) were collected at heading, anthesis, and milk stages. Multiple linear regression (MLR), support vector machine (SVM), and random forest (RF) regression models were utilized to predict seed yield. In 2022, the results indicated that nitrogen application provided a sufficiently large range of variation of seed yield (ranging from 45.79 to 379.45 kg ha⁻¹). Correlation analysis showed that the indices of the RVI, the NDVI, the LNC, and the LAI in 2022 presented significant positive correlation with seed yield, and the highest correlation coefficient was observed at the heading stage. The data from 2022 were utilized to formulate a predictive model for seed yield. The results suggested that utilizing data from the heading stage produced the best prediction performance. SVM and RF outperformed MLR in prediction, with RF demonstrating the highest performance (R2 = 0.75, RMSE = 51.93 kg ha-1, MAE = 29.43 kg ha-1, and MAPE = 0.17). Notably, the accuracy of predicting seed yield for the year 2023 using this model had decreased. Feature importance analysis of the RF model revealed that LNC was a crucial indicator for predicting smooth bromegrass seed yield. Further studies with an expanded dataset and integration of weather data are needed to improve the accuracy and generalizability of the model and adaptability for the growing year.

Exogenous melatonin promotes salt tolerance in smooth bromegrass seedlings: physiological, transcriptomic, and metabolomic evidence.

Soil salinization, which severely limits crop yield and quality, has become a global environmental and resource issue. Melatonin plays an important role in plant responses to salt stress. Smooth bromegrass is an important forage with excellent feed value and is widely grown in northern and north-west China for pasture and sand binding. However, the physiological and molecular mechanisms underlying exogenous melatonin regulation of salt stress in smooth bromegrass are not clear. This study compared the phenotype, physiological, transcriptome, and metabolome profiles of two varieties with contrasting salt tolerance attributes under salt and melatonin treatment. After melatonin treatment, the catalase (CAT) and ascorbate peroxidase (APX) activity, proline content, actual photochemical efficiency (Y(II)), relative water content, and fresh weight above ground were significantly higher than under salt treatment, while relative conductivity, H2O2 content, and Na+/K+ ratio were significantly lower than salt treatment. The transcriptome and metabolite profiling analysis of smooth bromegrass seedlings treated without melatonin under salt stress identified the presence of 22522 differentially expressed genes (DEGs) and 862 differentially expressed metabolites (DEMs) in SS, 17809 DEGs and 812 DEMs in ST, while treated with melatonin under salt stress identified the presence of 7033 DEGs and 177 DEMs in SS, 2951 DEGs and 545 DEMs in ST. Furthermore, in response to salt stress, melatonin may be involved in regulating the correlation between DEGs and DEMs in flavonoid biosynthesis, proline biosynthesis, and melatonin biosynthesis. Moreover, melatonin participated in mediating melatonin biosynthesis pathways and affected the expression of ASMT in response to salt stress.

Preliminary Study on Ecological Restoration Technology of Highway Slopes in High Altitude Mountain Areas—Taking Gansu Zhuohe Expressway Phase I Project as an Example

This study focuses on the technical difficulties of ecological restoration of highway slopes in high-altitude mountainous areas. Based on the theory of ecological restoration, starting from the characteristics of the ecological environment of highway slopes and the current status of ecological restoration technology of highway slopes, combined with the first phase of the Zhuoni Hezuo Expressway project in Gansu Province, we conducted research on ecological restoration technology of highway slopes in high-altitude mountainous areas. Based on the characteristics of the project and the natural environment, On the basis of investigation and evaluation of slope restoration design, it was proposed to add local leguminous plant combinations, including Astragalus adsurgens, yellow clover, and small crown flower. Grass family plants were selected, including smooth bromegrass, drooping elymus, flat ice grass, Chinese fescue, and cold early maturing bluegrass. The plant combination design was carried out; At the same time, according to the characteristics of the slope, ecological protection technologies such as vegetation blanket, spraying thin soil, planting bags+hydraulic spraying+planting shrub seedlings have been proposed for the slope; And proposed requirements for surface soil utilization and plant maintenance. This study aims to explore a technical solution suitable for ecological restoration of highway slopes in the Gannan region, in order to improve the stability and erosion resistance of slopes, improve the ecological environment, and ensure the safe operation of highways. It has guiding significance for ecological restoration of highway slopes in high-altitude mountainous areas and can be used as a reference for research on rock slope restoration in other regions.

Transcriptome analysis and physiological changes in the leaves of two Bromus inermis L. genotypes in response to salt stress.

Soil salinity is a major factor threatening the production of crops around the world. Smooth bromegrass (Bromus inermis L.) is a high-quality grass in northern and northwestern China. Currently, selecting and utilizing salt-tolerant genotypes is an important way to mitigate the detrimental effects of salinity on crop productivity. In our research, salt-tolerant and salt-sensitive varieties were selected from 57 accessions based on a comprehensive evaluation of 22 relevant indexes, and their salt-tolerance physiological and molecular mechanisms were further analyzed. Results showed significant differences in salt tolerance between 57 genotypes, with Q25 and Q46 considered to be the most salt-tolerant and salt-sensitive accessions, respectively, compared to other varieties. Under saline conditions, the salt-tolerant genotype Q25 not only maintained significantly higher photosynthetic performance, leaf relative water content (RWC), and proline content but also exhibited obviously lower relative conductivity and malondialdehyde (MDA) content than the salt-sensitive Q46 (p < 0.05). The transcriptome sequencing indicated 15,128 differentially expressed genes (DEGs) in Q46, of which 7,885 were upregulated and 7,243 downregulated, and 12,658 DEGs in Q25, of which 6,059 were upregulated and 6,599 downregulated. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the salt response differences between Q25 and Q46 were attributed to the variable expression of genes associated with plant hormone signal transduction and MAPK signaling pathways. Furthermore, a large number of candidate genes, related to salt tolerance, were detected, which involved transcription factors (zinc finger proteins) and accumulation of compatible osmolytes (glutathione S-transferases and pyrroline-5-carboxylate reductases), etc. This study offers an important view of the physiological and molecular regulatory mechanisms of salt tolerance in two smooth bromegrass genotypes and lays the foundation for further identification of key genes linked to salt tolerance.

Improving Drought Tolerance in Smooth Bromegrass by Mild Drought Stress Induction in Vegetative Growth Stage

Improving Drought Tolerance in Smooth Bromegrass by Mild Drought Stress Induction in Vegetative Growth Stage

167 Timing of Implants use in a Backgrounding System

Abstract A 2-year study conducted at the Eastern Nebraska Research and Extension Center near Mead, Nebraska determined the effects of backgrounding rate of gain and implanting during the winter or summer phases on animal performance and carcass traits. The study design was a 2 x 3 factorial arrangement with the factors of winter gain (0.45 or 0.90 kg/d; LG and HG, respectively) and three implant strategies. The implant strategies included a 36 mg zeranol (Ralgro; Merck Animal Health, De Soto, KS) implant during the winter phase and 40 mg trenbolone acetate and 8 mg estradiol (Revalor-G; Merck Animal Health) implant during the summer phase (STRNG), no implant during the winter phase and Rev-G during the summer phase (MED), and no implant during the winter or summer phases (NONE). The study used 240 (initial BW = 247 kg, SD = 5.9 kg YR 1; BW = 255 kg, SD = 10.9 kg YR 2) weaned steers each year that were fed one of two backgrounding diets consisting of bromegrass hay and 10% MDGS (LG) or 30% MDGS (HG). Steers were backgrounded in the feedlot for a 148-day winter phase followed by a 56-day summer phase where they grazed smooth bromegrass paddocks. Upon arrival in the feedlot for the finishing phase, steers received 200 mg TBA and 40 mg estradiol (Revalor-XS; Merck Animal Health) and were fed a common diet for the entire finishing phase. In the winter phase, steers fed the HG diet had a greater ADG, ending BW, DMI, and improved G:F over steers fed LG (P &amp;lt; 0.01). Steers that received a Ralgro implant during the winter phase (STRNG) were observed to have an 13% improved ADG (P &amp;lt; 0.01), a 10% increase in G:F (P &amp;lt; 0.01), and an additional 14 kg of BW for the winter phase. There were no interactions between the rate of gain and implant strategy (P ≥ 0.15) during the winter period. In the summer, HG steers had maintained greater ending BW than LG, although LG steers had greater ADG than HG (0.70 and 0.53 kg, respectively; P &amp;lt; 0.01) due to compensatory gain. Steers assigned to HG during the winter phase had a greater IBW for the finishing phase. Steers fed HG during the winter and administered an implant at both backgrounding phases (STRNG) had the greatest HCW with no differences in ADG or G:F during the finishing phase. Combining a strong implant program and an increased rate of gain during winter backgrounding resulted in 34 kg of additional HCW at marketing. Implant strategy and rate of gain during the winter growing period had additive effects to increase animal performance through all phases.

157 Daily Versus Three Times a Week Ddgs Supplementation on Grazing Calves

Abstract Supplemental feed may be provided to cattle in grazing systems to increase ADG, but can be labor intensive. This study evaluated the performance of steers grazing smooth bromegrass pastures supplemented dried distillers grains plus solubles (DDGS) either daily or three times per week. Crossbred steers (n = 144, initial BW 317 ± 1.25 kg) were used in a randomized complete block design with 3 treatments allocated randomly to 24 paddocks in one of 6 blocks. Treatments consisted of: 1) steers supplemented daily with 0.8% of BW (DM-basis) of DDGS, 2) steers supplemented three times a week with 1.86% of BW (DM-basis) of DDGS, and 3) steers that received no supplementation (control). All steers were implanted with 40 mg trenbolone acetate and 8 mg estradiol (Rev-G; Merck Animal Health, De Soto, KS) implants. Paddocks were divided equally into three strips and rotationally grazed. Put-and-take steers were utilized to match stocking rate with forage growth. Each treatment group rotated through three 0.81-hectare strips per pasture. Pre-graze and post-graze biomass was measured at ground level from each paddock at each rotation. Pre-graze biomass samples were used to determine forage availability. Grazing was initiated in early May with cattle removed from pastures in August, for a total of 97 grazing days. Data were analyzed with MIXED procedure of SAS with paddock as experimental unit and treatment and block as fixed effects. Treatment means of ADG and ending BW differed (P &amp;lt; 0.01) among treatments. The control calves gained 0.85 kg/d. The supplemented treatments significantly increased (P &amp;lt; 0.01) ADG compared with the control, with daily supplementation gaining 1.25 kg/d and 3x gaining 1.11 kg/d. The ADG was decreased (P &amp;lt; 0.01) with 3x a week compared with daily supplementation. The differences in ADG resulted in similar differences in final live BW. The control had a finial live BW of 398 kg and final live BW of both supplemented treatments was significantly increased (P &amp;lt; 0.01) when compared with the control treatment. Final live BW of 3x supplemented steers (423 kg) was decreased (P &amp;lt; 0.01) when compared with daily supplemented steers (436 kg). For steers grazing smooth bromegrass pastures, daily supplementation of DDGS resulted in greater gains and therefore greater final BW when compared with three times a week supplementation and the non-supplemented control.

94 Characterizing Yearling Beef Steers Grazing on Smooth Bromegrass Pasture Using Global Positioning Technology

Abstract Extensive grazing systems often vary in pasture size and terrain, making it challenging for ranchers to accurately locate livestock through visual appraisal. Using satellite-based global positioning systems (GPS), accurate position data can be provided to track animal movements that could inform grazing management decisions. This study aimed to: 1) assess two modern GPS devices for functionality by calculating fix success rate, and 2) evaluate the relationship between average daily distance traveled and average daily weight gain (ADG) performance on yearling steers grazing smooth bromegrass pasture using the GPS devices. Yearling steers (n = 25) grazed a 10.8-ha smooth bromegrass pasture for 156 days from May to September 2021. The temperature ranged from 4.1 to 38.8ºC with an average 22.7ºC and received 490 mm of rainfall. Cattle ADG was 0.65 ± 0.13 kg/d. Each steer was assigned two GPS collars for 28 days to compare two types of sensors. The sensors evaluated were i-gotU GT-600 travel loggers (GU) and Yabby LoRaWAN GPS sensors (YB) utilizing the IoT (Internet of Things) technology. The YB sensor possessed real-time monitoring and remote data access, while data from the GU sensor needed to be removed from the animals and manually downloaded. The YB sensors had a manufacturer declared finest positioning accuracy of 4.6 m, while that of the GU sensor being 9.1 m. With a 10-min sampling rate, battery life of the YB sensors lasted 4 weeks, while the GU sensors demonstrated unreliable battery performance that ranged between 1 to 4 weeks. Fixed success rate (FSR) was calculated for each sensor. Using PROC MIXED of SAS (v 9.4), on average the GU sensors had a 67.1% FSR and the YB sensors observed an 89.9% FSR (P &amp;lt; 0.0001). The YB sensor outweighed the GU sensor on battery life and FSR, thus was utilized throughout the duration of the grazing season. Individual animal traveled distance was calculated after converting the GPS coordinates in decimal degrees to Universal Transverse Mercator coordinates (WGS 1984 UTM zone 14N) in meters. The Euclidean distance between consecutive coordinates was calculated and summed daily to represent the daily traveled distance of an animal. Using all coordinates recorded from YB, steers traveled 2,718 ± 809 m/d. Statistical analysis was conducted using PROC CORR of SAS to determine the correlation between the daily averages of distance traveled and ADG. All values were considered significant α ≤ 0.05. There was no correlation observed between distance traveled and ADG (P ≥ 0.76). Results demonstrate that modern GPS sensors utilizing IoT technology have benefits over traditional GPS sensors and can be used as a tool for extensive grazing livestock tracking.

First Report of Leaf Spot Disease Caused by Epicoccum nigrum on Smooth Bromegrass (Bromus inermis) in China.

Smooth bromegrass (Bromus inermis Leyss.) is an excellent forage species widely distributed in Gansu, Qinghai, Inner Mongolia, and other provinces of China (Gong et al. 2019). In July 2021, typical leaf spot symptoms were observed on the leaves of smooth bromegrass plants in Ewenki Banner of Hulun Buir, China (49°5'8″N, 119°44'28″E, alt. 622.5 m). Approximately 90% of plants were affected, with symptoms apparent throughout the plant but mainly concentrated on the lower middle leaves. We collected 11 plants to identify the causal pathogen of leaf spot on smooth bromegrass. Samples (5×5 mm) of symptomatic leaves were excised and surface-sanitized with 75% ethanol for 3 min, rinsed three times with sterile distilled water, and incubated on water agar (WA) at 25℃ for three days. The lumps were cut along the edges and transplanted to potato dextrose agar (PDA) for subculture. After two purification cultures, ten strains, termed HE2 to HE11, were collected. The front side of the colony morphology was cottony or woolly, the center was greyish-green, circled with greyish-white color, with reddish pigmentation on the reverse. The conidia were globose or subglobose, yellow-brown or dark brown, with surface verrucae, and 23.89±3.76×20.28±3.23 μm (n = 50) in size. The morphological characteristics of the mycelia and conidia of the strains mtched those of Epicoccum nigrum (El-Sayed et al. 2020). The primers ITS1/ITS4 (White et al. 1991), LROR/LR7 (Rehner and Samuels 1994), 5F2/7cR (Sung et al. 2007), and TUB2Fd/TUB4Rd (Woudenberg et al. 2009) were used to amplify and sequence four phylogenic loci (ITS, LSU, RPB2 and β-tubulin), respectively. The sequences of ten strains have been deposited in GenBank, and the detailed accession numbers were shown in Table S1. BLAST analysis of these sequences showed 99-100%, 96-98%, 97-99% and 99-100% homology with the E. nigrum strain in the ITS, LSU, RPB2 and TUB sequenced regions, respectively. The sequences of ten test strains and other Epicoccum spp. strains obtained from GenBank were aligned by ClustalW by MEGA (version 11.0) software. After a series of alignment, cutting and splicing, the phylogenetic tree was constructed by the neighbor-joining method with 1000 bootstrap replicates based on the ITS, LSU, RPB2, and TUB sequences. The test strains were clustered together with E. nigrum, with branch support rate of 100%. Combined with morphological and molecular biological characteristics, ten strains were identified as E. nigrum. For the pathogenicity test, the seeds of smooth bromegrass were soaked for four days and then sown into six pots (10 cm diameter × 15 cm height) and kept in a greenhouse under a 16-h photoperiod with temperatures of 20-25°C and 60% relative humidity. Microconidia of the strain produced on wheat bran medium after 10 days were washed with sterile deionized water, filtered through three layers of sterile cheese cloth, quantified, and the concentration adjusted to 1 × 106 microconidia/ml with a hemocytometer. When the plants had grown to a height of about 20 cm, the leaves of plants in three pots were sprayed with the spore suspension, 10 mL per pot, while the remaining three pots were inoculated with sterile water and served as controls (LeBoldus and Jared 2010). The inoculated plants were cultured in an artificial climate box under a 16-h photoperiod with temperatures of 24°C and 60% relative humidity. Brown spots were apparent on the leaves of the treated plants after five days, whereas the leaves of the controls remained healthy. The same E. nigum strain were re-isolated from the inoculated plants and identified by the morphological and molecular techniques described above. To our knowledge, this is the first report of leaf spot disease caused by E. nigrum on smooth bromegrass in China, as well as in the world. Infection with this pathogen could reduce the yield and quality of smooth bromegrass production. For this reason, strategies for the management and control of this disease should be developed and implemented.

Soil total carbon and nitrogen under long‐term perennial bioenergy crops receiving various nitrogen fertilization rates

AbstractPerennial crops may sequester greater soil carbon (C) and nitrogen (N) than annual crops due to higher root biomass production, but the potential of long‐term cultivation of perennial bioenergy crops receiving various N fertilization rates in sequestering C and N needs further exploration. Soil samples (0–120 cm) collected from 2009 to 2019 under perennial bioenergy crops receiving various N fertilization rates and an annual crop were analyzed for soil total C (STC) and N (STN) in the US northern Great Plains. Perennial bioenergy crops were intermediate wheatgrass (IW, Thinopyrum intermedium [Host] Barkworth and Dewey), smooth bromegrass (SB, Bromus inermis L.), and switchgrass (SG, Panicum virgatum L.); N fertilization rates were 0, 28, 56, and 84 kg N ha−1, and annual crop was spring wheat (WH, Triticum aestivum, L.). The STC increased, but STN decreased by soil depth, regardless of treatments and years. At 0–120 cm, IW sequestered C at 10.6 Mg C ha−1 year−1 compared with 5.4–6.8 Mg C ha−1 year−1 for SB and SG from 2009 to 2019. Nitrogen fertilization rate had limited effect on STC and STN. At 0–30 cm, STC was 2.0–5.4 Mg C ha−1 greater and STN 0.10–0.24 Mg N ha−1 greater with perennial bioenergy crops than WH. Long‐term cultivation of IW can sequester more C in the soil to a greater depth than SB and SG and perennial bioenergy crops can sequester more C and N at the surface layer than an annual crop in the semiarid region of the US northern Great Plains.

Effects of Long-Term Drought Stress and Variation in Traits Related to Post-Drought Recovery, Persistence, and Summer Dormancy in Two Species of Orchardgrass (Dactylis glomerata L.) and Smooth Bromegrass (Bromus inermis Leyss.)

Effects of Long-Term Drought Stress and Variation in Traits Related to Post-Drought Recovery, Persistence, and Summer Dormancy in Two Species of Orchardgrass (Dactylis glomerata L.) and Smooth Bromegrass (Bromus inermis Leyss.)

The eroded slopes alkalization peculiarities in southern part of western Forest Steppe

A significant part of arable lands on slopes is subject to removal from active processing, and to alkalization with perennial herbs. We know that the most productive are those agro-phytocenoses, forming based on a single-species sowing of alfalfa (Lucerne), and its mixture with perennial cereal grasses. However, the restrictive factor of forming alfalfa-cereal grasslands high productivity is the soil solution acid reaction. The research carried out in 2017–2020 showed that lime application has significantly affected the soil solution reaction. Almost in all variants with liming, the values approached neutral. Besides, the soil liming was an effective factor of the researched grasslands productivity increase. So, a herbal mixture: red clover + alfalfa + timothy grass, on the background without liming and introducing phosphorus-potassium fertilizers, averagely for 2017–2020 has provided the output of 5,93 t/ ha of dry matter. On deacidified plots, the given herbal mixture productivity has increased to 7,52 t/ha of dry matter. The combination of soil liming and phosphorus-potassium fertilizers application has supplied the maximum dry matter output from the herbal mixture: red clover + alfalfa + smooth bromegrass – 8,66 t/ha, which exceeded by 27,5 % the unfertilized variant. The soil chemical melioration and phosphorus-potassium fertilizers application have proved to be the important factors of increasing the leguminous components part in the botanical component of a green mass yield. Particularly, in the most productive herbal mixture: red clover + alfalfa + smooth bromegrass, on the limed and fertilized background, a leguminous component part in the first and second mowings has increased by 20,9 and 17,4 %, respectively. Thus, the legume-cereal grasslands averagely for the first four years of usage provide the 5,93–8,66 t/ ha dry matter output, containing 32–63,8 % of a leguminous component. The soil chemical melioration, as well as phosphorus-potassium fertilizers application have increased the legume-cereal grasslands productivity by 27,5–27,9 %, and enlarged the leguminous components part by 17,4–20,9 %. Key words: sloping lands, soil liming, herbal mixture, alfalfa (Lucerne), timothy grass, smooth bromegrass, productivity, botanical composition.

Fermentation Properties and Bacterial Community Composition of Mixed Silage of Mulberry Leaves and Smooth Bromegrass with and without Lactobacillus plantarum Inoculation

To evaluate the fermentation properties and bacterial community composition of mulberry leaves when ensiled with smooth bromegrass, and the effects of Lactobacillus plantarum inoculation on the mixed silage of mulberry leaves and smooth bromegrass, mulberry leaves were mixed with smooth bromegrass at ratios of 100:0, 90:10, 80:20, 70:30 and 60:40, and ensiled for 60 d with and without L. plantarum inoculant. The results showed that the sole fermentation of mulberry leaves failed to achieve optimum fermentation quality. Silage with a mulberry leaf ratio of 80% performed better fermentation quality compared with other non-inoculated groups, indicated by lower pH value, adequate lactic acid accumulation, and enriched proportion of Lactobacillus in the bacterial community. L. plantarum inoculation dramatically improved fermentation quality of mulberry leaf silage compared with the non-inoculated control. However, the fermentation quality of the inoculated silage decreased along with the reduction in the ratio of mulberry leaves. In conclusion, L. plantarum inoculation has the capability to improve the silage quality of mulberry leaves. Combined ensiling with smooth bromegrass could also aid in improving silage quality of mulberry leaves, with the optimum ratio of mulberry leaves being 80%.

Synergistic use of optical and biophysical traits to assess Bromus inermis pasture performance and quality under different management strategies in Eastern Nebraska, U.S.

We investigated the synergic use of optical and biophysical traits to characterize Bromus inermis (smooth bromegrass) pasture lands and assess the combined effects of long-term (15-years) rotational grazing and management strategies of (i) no fertilization (C), (ii) mineral nitrogen (N) fertilization (HF), and (iii) supplemented fertilization through dry distiller grains plus soluble (DDGS; SF)- on forage growth, performance, and quality. We found that fertilization improved pasture’s biomass, specific leaf area, leaf area index (LAI), as well as forage quality. The use of N fertilization did not offer an advantage (e.g., forage quality, yield) over DDGS under both grazed and ungrazed conditions. Optical, proximal sensing techniques allowed the characterization of pasture lands in a non-invasive and time-efficient manner. We tested established vegetation indices (VIs) for their accuracy in identifying and quantifying important physiological and morphological traits. Results showed that the Normalized Difference Vegetation Index (NDVI) and Vogelmann (VOG) were among the best performing indices. Results contribute to our understanding of the impact of long-term fertilization management on Bromus inermis pastures and validate the use of proximal sensing methods. Proximal sensing methods provide direct, non-invasive, and time efficient tool for assessment of the performance and health of vegetation, keys to successful integrative management strategies.