Warm-season Grasses Research Articles

Molecular Characterization and Phylogenetic Analysis of Centipedegrass [Eremochloa ophiuroides (Munro) Hack.] Based on the Complete Chloroplast Genome Sequence.

Centipedegrass (Eremochloa ophiuroides) is an important warm-season grass plant used as a turfgrass as well as pasture grass in tropical and subtropical regions, with wide application in land surface greening and soil conservation in South China and southern United States. In this study, the complete cp genome of E. ophiuroides was assembled using high-throughput Illumina sequencing technology. The circle pseudomolecule for E. ophiuroides cp genome is 139,107 bp in length, with a quadripartite structure consisting of a large single copyregion of 82,081 bp and a small single copy region of 12,566 bp separated by a pair of inverted repeat regions of 22,230 bp each. The overall A + T content of the whole genome is 61.60%, showing an asymmetric nucleotide composition. The genome encodes a total of 131 gene species, composed of 20 duplicated genes within the IR regions and 111 unique genes comprising 77 protein-coding genes, 30 transfer RNA genes, and 4 ribosome RNA genes. The complete cp genome sequence contains 51 long repeats and 197 simple sequence repeats, and a high degree of collinearity among E. ophiuroide and other Gramineae plants was disclosed. Phylogenetic analysis showed E. ophiuroides, together with the other two Eremochloa species, is closely related to Mnesithea helferi within the subtribe Rottboelliinae. These findings will be beneficial for the classification and identification of the Eremochloa taxa, phylogenetic resolution, novel gene discovery, and functional genomic studies for the genus Eremochloa.

Genome-Wide Identification and Characterization of the TIFY Gene Family and Their Expression Patterns in Response to MeJA and Aluminum Stress in Centipedegrass (Eremochloa ophiuroides)

The TIFY family is a group of novel plant-specific transcription factors involved in plant development, signal transduction, and responses to stress and hormones. TIFY genes have been found and functionally characterized in a number of plant species. However, there is no information about this family in warm-season grass plants. The current study identified 24 TIFY genes in Eremochloa ophiuroides, a well-known perennial warm-season grass species with a high tolerance to aluminum toxicity and good adaptability to the barren acidic soils. All of the 24 EoTIFYs were unevenly located on six out of nine chromosomes and could be classified into two subfamilies (ZIM/ZML and JAZ), consisting of 3 and 21 genes, respectively, with the JAZ subfamily being further divided into five subgroups (JAZ I to JAZ V). The amino acids of 24 EoTIFYs showed apparent differences between the two subfamilies based on the analysis of gene structures and conserved motifs. MCScanX analysis revealed the tandem duplication and segmental duplication of several EoTIFY genes occurred during E. ophiuroides genome evolution. Syntenic analyses of TIFY genes between E. ophiuroides and other five plant species (including A. thaliana, O. sativa, B. distachyon, S. biocolor, and S. italica) provided valuable clues for understanding the potential evolution of the EoTIFY family. qRT-PCR analysis revealed that EoTIFY genes exhibited different spatial expression patterns in different tissues. In addition, the expressions of EoTIFY genes were highly induced by MeJA and all of the EoTIFY family members except for EoJAZ2 displayed upregulated expression by MeJA. Ten EoTIFY genes (EoZML1, EoZML1, EoJAZ1, EoJAZ3, EoJAZ5, EoJAZ6, EoJAZ8, EoJAZ9, EoJAZ10, and EoJAZ21) were observed to be highly expressed under both exogenous MeJA treatment and aluminum stress, respectively. These results suggest that EoTIFY genes play a role in the JA-regulated pathway of plant growth and aluminum resistance as well. The results of this study laid a foundation for further understanding the function of TIFY genes in E. ophiuroides, and provided useful information for future aluminum tolerance related breeding and gene function research in warm-season grass plants.

Native Warm-Season Grass Response to Nitrogen Fertilization

The identification of appropriate nitrogen (N) rates for native warm-season grasses (NWSG) is needed to inform forage management in the southeastern United States. Experiments were conducted in Knoxville and Springfield, TN, from 2015 to 2019, to evaluate dry matter (DM) yield, forage nutritive value (FNV), the influence of temperature and precipitation on yield, and partial factor productivity (PFP) responses. Three NWSG species (big bluestem [BB; Andropogon gerardii Vitman], switchgrass [SG; Panicum virgatum L.], and eastern gamagrass [EG; Tripsacum dactyloides L.]) were grown at each location and harvested twice annually. Five N rates in the form of urea were applied annually in split applications. The yields for all species responded positively to nitrogen (p < 0.001) and the time of harvest (p < 0.001) at both sites, except for BB yield at Springfield; no consistent N effects were observed over years. Nitrogen affected the FNV (p < 0.001) of all species, increasing CP by three to five percentage points (p < 0.001). Yields across all species and locations responded positively to precipitation (p < 0.001) and temperature (p < 0.001). A moderate N amendment (<135 kg N ha−1 yr−1, based on PFP) can enhance the productivity of NWSG, but responses were site-dependent and influenced by temperature and precipitation.

Effect of wheat middling incorporation into wet corn distillers grains with solubles on apparent diet digestibility and ruminal fermentation characteristics in growing and finishing diets.

Two separate cross-over experiments were conducted to evaluate the effects of incorporating wheat middlings into wet corn distillers grains with solubles (WDGS) on apparent diet digestibility and ruminal fermentation characteristics in growing and finishing diets. In experiment 1, four ruminally cannulated heifers (313 ± 42.9kg) were limit fed a high-energy growing diet that included WDGS (CON) or WDGS + wheat middlings (CON + WM) at 40% of diet dry matter (DM). The diet also contained (DM basis) 39.5% dry-rolled corn, 7.5% supplement, and 13% warm-season grass hay. In experiment 2, four ruminally cannulated Holstein steers (321 ± 17.4kg) were fed a finishing diet that included WDGS (CON) or WDGS + wheat middlings (CON + WM) at 30% of diet DM. The diet also contained (DM basis) 60.3% dry-rolled corn, 2.7% supplement, and 7.0% warm-season grass hay. Experiments consisted of two 15-d periods that were conducted concurrently. Each period included 10 d of diet adaptation, 4 d of fecal collection, and 1 d of ruminal fluid collection. Fecal samples were collected on days 11 to 14 of each period and composite samples were analyzed for chromium to estimate apparent diet digestibility. On day 15, ruminal fluid samples were collected prior to feeding and again at 2, 4, 6, 8, 12, 18, and 24-h post-feeding. In experiment 1, DM, organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) intake did not differ (P ≥ 0.11) between diets; however, starch intake was greater (P = 0.03) for heifers fed CON + WM compared with CON. Apparent DM, OM, NDF, and starch digestibilities were similar between diets (P ≥ 0.13), but feeding CON + WM tended to lead to lesser (P = 0.06) apparent ADF digestibility. Ruminal pH and total volatile fatty acid concentrations did not differ between diets (P ≥ 0.16); however, ruminal ammonia concentrations tended to be less (P = 0.09) for CON + WM compared with CON. In experiment 2, DM intake did not differ (P = 0.65) between diets. Apparent DM digestibility was greater (P = 0.01) for CON + WM compared with CON but the difference was small. Intake and apparent digestibility of OM, NDF, ADF, and starch did not differ (P ≥ 0.25) between diets. Ruminal ammonia concentrations were lesser (P = 0.03) while ruminal pH was greater (P = 0.02) for CON + WM compared with CON. Overall, incorporation of wheat middlings into WDGS had minimal impacts on feed intake, apparent diet digestibility, and ruminal fermentation characteristics when fed to growing and finishing cattle.

Paleobiology of Pleistocene large land mammals from the Brazilian Pampa

The southern Brazilian Pleistocene fauna exhibited a rich diversity of large mammalian herbivores, which are now extinct or locally extinct. In this study, we employed stable isotope analysis to investigate the past ecology of these animals. Specifically, we examined the carbonate fraction of bones and teeth and utilized compiled carbon and oxygen isotopic ratios from previous research publications. The δ13C values indicated that most specimens inhabited grassland environments, which aligns with environmental reconstructions based on pollen records of the “Campos” region. The dominant food resource for these herbivores consisted of C3 photosynthesizers, mainly cool-season grasses. This preference can be attributed to the higher abundance and nutritional quality of cool-season grasses compared with warm-season grasses employing C4 photosynthesis. The variability in δ18O values within and between taxa may suggest a seasonal climate. Based on these findings, we conclude that the environmental changes during the Pleistocene-Holocene transition were detrimental to the survival of these large herbivores.

423 Effects of Prescribed Fire Timing on Stocker Cattle Performance and Native Plant Species Composition in the Kansas Flint Hills

Abstract Ranchers in the Kansas Flint Hills apply spring-season prescribed fire to improve growth performance of yearling stocker calves, increase native warm-season grass production, and reduce encroachment of woody and invasive plant species. Shifting prescribed fire application from spring (i.e., April) to late summer (i.e., August) or early fall (i.e., September) can reduce Sericea lespedeza infestation, increase native forb diversity, and improve air quality by distributing smoke produced from burning the Flint Hills throughout the year. Effects of late-summer or early-fall prescribed fire on yearling grazing cattle performance is unknown; therefore, our objective was to determine the impact of prescribed-fire timing on growth performance of yearling grazing cattle and plant community characteristics in the Kansas Flint Hills. Over a four-year period, 18 pastures were grouped by watershed and each watershed was assigned to one of three prescribed-fire treatments (24 pastures/treatment): spring (9 April ± 5.1 d), summer (23 August ± 4.9 d), or fall (29 September ± 8.7 d). Burn treatments were applied in years 1, 2, and 3 but were not applied in year 4 due to unfavorable burn conditions. Over 4 consecutive grazing seasons, 1,416 yearling calves (initial BW = 304 ± 49.6 kg) were grazed from May to August following prescribed fire application. Calves were grazed for 90 d at a targeted stocking density of 280 kg live-weight· ha-1. A permanent 100 m transect was established in each pasture and was used to determine plant species composition and soil cover using a modified step-point method. Plant species composition was determined annually in June. Data were analyzed as a completely random design using a mixed model. The final model contained treatment as a fixed effect and year and pasture within treatment as random effects. Average daily gain (ADG) tended to be greater (P = 0.06) for spring-burned pastures compared with fall-burned pastures, whereas ADG for summer-burned pastures were intermediate. Proportions of bare soil were greater (P < 0.01) in spring-burned pastures compared with summer- and fall-burned pastures. Conversely, proportions of litter on the soil surface were greatest (P < 0.05) in summer, intermediate (P < 0.05) in fall, and least (P < 0.01) in spring-burned pastures. Total grass, native grass, total forb, and native forb basal cover did not differ (P ≥ 0.13) among treatments. Conversely, basal cover of nectar-producing forbs was greater (P < 0.01) in fall-burned pastures compared with spring- and summer-burned pastures. Overall, fall prescribed-fire tended to reduce ADG; however, stocker cattle growth performance and native rangeland plant composition was similar between spring- and summer-burned pastures.

PSX-12 Effects of Cottonseed Meal Supplementation on Calf Performance and Forage Utilization Grazing Late Season Summer Forage

Abstract Nutritive quality of perennial warm-season grasses during summer may limit the DMI of growing calves due to low protein and increased NDF content. Cottonseed meal (CSM) supplementation may improve forage utilization by increasing rumen degradable protein, but research in calves is limited. It was hypothesized that supplementation of CSM to heifers grazing mature forage would have improved performance due to greater forage DMI and fiber digestibility. Objectives were to compare the effects of CSM supplementation on calf gain performance, estimated forage intake, and in vitro true digestibility (IVTD) and neutral detergent digestibility (IVNDFD) of low-quality, warm-season forage. Angus heifers (n = 18) weighing 232.7 ± 12.6 kg were blocked by BW (light, medium, and heavy) and allocated to 6 paddocks (1.64 ha) of W.W. B-Dahl Bluestem (Bothriochloa bladhii) for 67 d. Heifers were supplemented daily with a mineral mix and either no cottonseed meal (CON) or 454 g/animal of CSM (CSM1) in a RCBD with a 2×3 factorial arrangement of treatments and BW blocks, respectively. Initial and final shrunk BW was measured to calculate total gain, ADG, and percent of BW gained. Forage samples were collected weekly and composited into 3 periods for chemical analysis and in vitro incubations. Forage DMI was estimated using a double sampling technique for each paddock within period. Forage IVTD and IVNDFD were analyzed using batch fermentation with and without CSM in a CRD (2 treatments by 3 periods). Mean forage CP during periods 1 and 2 were 5.75% and increased to 10.3% in period 3 (P < 0.01). Forage NDF content increased over time (64.1 vs. 69.3%; P < 0.01) and estimated forage DMI of heifers tended (P = 0.07) to decrease from 2.9 to 2.1% of BW. Treatment did not affect estimated forage DMI (P = 0.40). Heifers receiving CSM1 gained 28.3% more BW than heifers receiving CON (47.27 vs. 36.82 kg, respectively; P = 0.02). Percent of BW gained was greater for heifers receiving CSM1 than CON (16.9 vs. 13.8% of initial BW, respectively, P = 0.029). There were no treatment by period interactions on IVTD or IVNDFD. The IVTD of forage from period 1 was greater than periods 2 and 3 (49.9 vs. 47.1 and 46.6%, respectively; P = 0.005). The IVTD of forage incubated with CSM tended (P = 0.06) to be greater than forage without CSM (52.1% vs. 47.8%, respectively). The IVNDFD was not affected by period but tended to be greater with CSM inclusion (P = 0.09) relative to CON (24.83% vs. 18.95%, respectively). In conclusion, 454 g/d of CSM supplemented to heifers grazing late-summer W.W. B-Dahl Bluestem forage likely provided sufficient protein to alter ruminal fiber digestibility, without affecting forage intake, and had measurable effects on gain.

234 Can We Use Moderate Quality Round Bale Bermudagrass Silage to Stretch Wheat pasture?

Abstract Grazing wheat pasture with growing calves is an economically important enterprise in the Southern Great Plains and Southeastern U.S. Wheat forage is available when there are few other high quality forage options, and a offers a favorable seasonality of net returns for the stocker cattle enterprise. Our objective was to determine if a moderate quality wrapped round bale silage can be used to profitably increase stocking rates during the fall and winter. This research was conducted at the University of Arkansas System Division of Agriculture Livestock & Forestry Research Station near Batesville, AR (35°50′N, 91°48′W; elevation 150 m) over 3-yr from fall 2018 to spring 2021. Treatments were: HCON, where steers were stocked at 2.47 steers/ha in the fall without bermudagrass baleage or were stocked at 1× (H1.0), 1.5× (H1.5), or 2× (H2.0) the HCON stocking rate with ad libitum access to bermudagrass round bale wrapped silage during the fall. In the spring all pastures were stocked at 5.56 steers/ha without baleage (HCON) or with access to baleage (H1.0, H1.5, H2.0). Steer performance, forage mass and nutritive quality were analyzed as a randomized complete block design with SAS 9.4 (SAS Inst. Inc. Cary, NC). The bermudagrass baleage was analyzed to be 48.8% DM in yr 1, 40.2% DM in yr 2, and 46.8% DM in yr 3; and ranged from 13 to 14% CP and 55 to 56% TDN across the 3-yr (Table 1). Baleage intake based on estimated disappearance from feeders increased (P < 0.01) with increasing stocking rate in the fall and tended (P = 0.07) to increase during the spring with increased fall stocking rate. Steer ADG showed a positive associative effect of baleage feeding in the fall with greater (P = 0.01) ADG for H1.0 than HCON, while HCON and H1.5 did not differ (P = 0.71), but were greater (P ≤ 0.03) than H2.0. Gain per hectare in the fall tended (P = 0.06) to be greater for H1.0 than HCON, H1.5 and H2.0 were greater (P < 0.01) than H1.0 but did not differ from each other. Performance and BW did not differ (P ≥ 0.73) during the spring, but steer grazing days/ha and BW gain/ha were greater when baleage was offered in the spring compared with HCON. Supplemental efficiency of feeding silage did not differ (P ≥ 0.47) among treatments, on the average gains were increased by 0.22 kg/kg baleage DM fed in the fall and 0.11 kg/kg baleage DM in the spring. Offering moderate quality warm-season grass baleage to steers on wheat pasture enabled increased stocking rates in the fall while maintaining acceptable levels of performance and extending the length of the grazing season in the spring.

Draft Genome Sequences of 11 Isolates of Ophiosphaerella spp., the Causal Agents of Several Turfgrass Diseases Including Spring Dead Spot of Bermudagrass and Necrotic Ring Spot of Kentucky Bluegrass

Ophiosphaerella herpotricha, O. korrae, and O. narmari are the causal agents of spring dead spot of warm-season grasses worldwide, and O. korrae is the causal agent of necrotic ring spot of cool-season grasses that primarily occurs in North and South America. All three species are considered important pathogens of turfgrasses, and there is limited genomic information about these ectotrophic, root-infecting fungi. Herein are reported the draft genome sequences of three isolates of O. herpotricha, five O. korrae, and three O. narmari isolates, furthering the knowledge about these three important turfgrass disease-causing species. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Diurnal greenhouse gas emissions and substrate temperatures from blue-green roofs in north-eastern Italy during a dry-hot summer season

Covering building rooftops with vegetation [Green roofs (GRs)] holds promise for lowering building temperatures, reducing stormwater runoff, and providing other ecosystem services, but it is unclear how this will impact greenhouse gas (GHG) emissions. The latter may also be influenced by vegetation type, substrate depth, and irrigation regime and we sought to test this by comparing daytime GHG emissions (i.e., CH4, CO2, and N2O) and daily substrate temperatures in 48 GR microcosms in North-eastern Italy during a dry-hot summer season (June to September). Four vegetation types (Sedum mixture, cold season grasses, warm season grasses, or wildflowers), two substrate depths (8 cm or 14 cm), and two irrigation levels (1 or 2 mm d−1) were evaluated, for a total of 16 treatments with 3 replicates. We found that vegetation type had a significant effect on temperature [average temp. of 24.8 °C (Sedum) vs 25.5 °C (warm season grasses)] and CH4, CO2, and N2O emissions. While all vegetation types had net CO2 emissions (median values from 147 to 671 mg m−2 h−1) and net N2O uptake (median values from -0.06 to -0.28 mg m−2 h−1), CH4 flux had net negative values (capture) only in microcosms with wildflowers (-0.07 mg m−2 h−1), whereas other treatments had a median CH4 emissions of 0.09 mg m−2 h−1. Substrate depth significantly affected CO2 and N2O fluxes with deeper substrate leading to higher CO2 emission (+ 60.7%) and greater N2O uptake (+ 30.8%). Irrigation level only significantly influenced N2O fluxes with 2 mm irrigation resulting in higher fluxes (-0.20 mg m−2 h−1) than 1 mm irrigation (-0.09 mg m−2 h−1). Our study suggests that under heat induced plant-stress conditions, GRs can improve N2O and CH4 capture but might increase the emissions of CO2 fixed by plants in the previous years in the substrate and that vegetation type and substrate depth can significantly alter emissions and are thus important design parameters.

Differential Regulations of Antioxidant Metabolism and Cold-Responsive Genes in Three Bermudagrass Genotypes under Chilling and Freezing Stress.

As a typical warm-season grass, bermudagrass growth and turf quality begin to decrease when the environmental temperature drops below 20 °C. The current study investigated the differential responses of three bermudagrass genotypes to chilling stress (8/4 °C) for 15 days and then freezing stress (2/-2 °C) for 2 days. The three genotypes exhibited significant variation in chilling and freezing tolerance, and Chuannong-3, common bermudagrass 001, and Tifdwarf were ranked as cold-tolerant, -intermediate, and -sensitive genotypes based on evaluations of chlorophyll content, the photochemical efficiency of photosystem II, oxidative damage, and cell membrane stability, respectively. Chuannong-3 achieved better tolerance through enhancing the antioxidant defense system to stabilize cell membrane and reactive oxygen species homeostasis after being subjected to chilling and freezing stresses. Chuannong-3 also downregulated the ethylene signaling pathway by improving CdCTR1 expression and suppressing the transcript levels of CdEIN3-1 and CdEIN3-2; however, it upregulated the hydrogen sulfide signaling pathway via an increase in CdISCS expression under cold stress. In addition, the molecular basis of cold tolerance could be associated with the mediation of key genes in the heat shock pathway (CdHSFA-2b, CdHSBP-1, CdHSP22, and CdHSP40) and the CdOSMOTIN in Chuannong-3 because the accumulation of stress-defensive proteins, including heat shock proteins and osmotin, plays a positive role in osmoprotection, osmotic adjustment, or the repair of denatured proteins as molecular chaperones under cold stress. The current findings give an insight into the physiological and molecular mechanisms of cold tolerance in the new cultivar Chuannong-3, which provides valuable information for turfgrass breeders and practitioners.

Fracking pond restoration in the western Rio Grande Plains, Texas: Stockpiled topsoils may not be necessary, but seeding helps

Soil disturbances that accompany energy development can damage local habitats. Prior to oil and gas extraction, it is commonly recommended that topsoil stockpiles be created to aid future restoration. Our study area, a retired fracking pond in the western Rio Grande Plains, Texas, was restored in 2017 with stockpiled topsoil that was collected in 2013. We segregated the existing stockpile into three layers that were ∼1.5 m in thickness and distributed these layers, along with a non-amended control surface (consisting of former subsoil that made up the perimeter of the fracking pond), in strips over the restoration area. Each of the four surfaces was seeded with a mixture of (1) 13 native grasses, (2) 13 native grasses plus an annual warm-season grass cover crop, or (3) non-seeded. We monitored plant density and species composition two through five years post-restoration. The non-amended control surface had higher seeded grass density during the final 2 sampling periods; stockpiled surfaces seldom differed from each other. Previous year's competing plant density had little effect on restoration success. Providing supplemental seed initially increased seeded plant density but benefits diminished over time; adding a cover crop was not advantageous. Changes in community composition over time were similar on stockpile surfaces but more variable than observed on the control surface. Results suggest that stockpiling topsoil may not be necessary, but that supplemental seeding was beneficial, to restoration success.

Development of genomic resources for Rhodes grass (Chloris gayana), draft genome and annotated variant discovery.

Genomic resources for grasses, especially warm-season grasses are limited despite their commercial and environmental importance. Here, we report the first annotated draft whole genome sequence for diploid Rhodes grass (Chloris gayana), a tropical C4 species. Generated using long read nanopore sequencing and assembled using the Flye software package, the assembled genome is 603 Mbp in size and comprises 5,233 fragments that were annotated using the GenSas pipeline. The annotated genome has 46,087 predicted genes corresponding to 92.0% of the expected genomic content present via BUSCO analysis. Gene ontology terms and repetitive elements are identified and discussed. An additional 94 individual plant genotypes originating from three diploid and two tetraploid Rhodes grass cultivars were short-read whole genome resequenced (WGR) to generate a single nucleotide polymorphism (SNP) resource for the species that can be used to elucidate inter- and intra-cultivar relationships across both ploidy levels. A total of 75,777 high quality SNPs were used to generate a phylogenetic tree, highlighting the diversity present within the cultivars which agreed with the known breeding history. Differentiation was observed between diploid and tetraploid cultivars. The WGR data were also used to provide insights into the nature and evolution of the tetraploid status of the species, with results largely agreeing with the published literature that the tetraploids are autotetraploid.

Adapting the CROPGRO Perennial Forage model to predict growth and development of Pensacola bahiagrass

Bahiagrass (Paspalum notatum Flüggé) – a warm-season perennial grass – is one of the most important forage species for livestock production in the southeastern United States. Bahiagrass pastures are often managed extensively, without the data and tools necessary for complex management. Crop simulation models have been previously developed for warm-season grasses, enabling forecast of physiological variables and evaluation of various management scenarios. The objective of this study is to calibrate the CROPGRO Perennial Forage model (CROPGRO-PFM) for bahiagrass and to evaluate the performance of the new model across six experimental datasets. Previously developed parameters for the palisadegrass (Brachiaria brizantha cv. Xaraes) model were used initially, followed by modification of parameters more predictive of bahiagrass and its differences from palisadegrass. Major changes included calibration of plant composition, cool season temperature sensitivity, and photoperiod-induced dormancy parameters, corresponding to previous observations of bahiagrass physiology. The final adapted model resulted in effective predictive accuracy for important state variables – harvested herbage mass (RMSE = 729 kg ha−1, d-index = 0.85), above-ground biomass (RMSE = 729 kg ha−1, d-index = 0.82) and crude protein concentration (RMSE = 3.1%, d-index = 0.71). Given the wide range of experimental conditions used for model development, these results suggest that the calibrated CROPGRO-PFM model will be effective for simulating physiological variables across bahiagrass pastoral systems.

Preliminary Survey of Mycotoxins Identified from Florida Bahiagrass Pastures

The beef cattle ranchers in Florida reported some health issues related to cattle grazing on warm-season grass pastures, such as bahiagrass and bermudagrass. The illness was not attributable to nutritional imbalances, or other possible causes. The focus then turned to what the animals were consuming, and forages were implicated. In general, the forages in Florida are just fine; however, sometimes under certain circumstances the fungi live in our forages may produce “secondary metabolites”. All forages harbor fungi. Some fungi are good in that they aid our forages to grow better, helping to mine nutrients from the soil or atmosphere. Sometimes they are not so good, like when high levels of ergotized seed occur in the seed heads of bahiagrass.

Identification of Cultured and Diazotrophic Bacterial Endophytes in Warm-Season Grasses

Endophytes can have positive effects on plant health and growth, but endophytes of warm-season grasses are largely understudied, and inocula are rarely applied to cultivated grasses. To identify endophytes in warm-season grasses, 35 endophytic bacterial isolates were cultured from the roots, rhizomes, and shoots of bermudagrass ( Cynodon dactylon), energy cane ( Saccharum spp.), Johnsongrass ( Sorghum halepense), napiergrass ( Cenchrus purpureus), perennial sorghum ( Sorghum bicolor × S. halepense), sorghum ( Sorghum bicolor), sorghum × sudangrass ( Sorghum × drummondii), and peanut (outgroup). Sequencing of the 16S rRNA fragment from the endophytes revealed that the bacterial sequences were similar to Bacillus spp. (19 isolates), Burkholderia spp. (4), Pantoea spp. (4), Pseudomonas spp. (3), Enterobacter spp. (2), Kosakonia spp . (2), and Sphingomonas sp. (1). To identify diazotrophic endophytes, DNA isolated from surface-disinfected tissue from warm-season grasses was used to amplify nifH. Bacteria containing nifH were similar to 13 genera, and sequences similar to Pseudolabrys sp. were present in the greatest number of warm-season grasses. Bacteria similar to Bradyrhizobium frederickii strain CNPSo 3447 were identified frequently from the leaves and roots of sorghum × sudangrass (and peanut roots). Using similarity to known nifH fragments, six genera were identified that had not been previously identified in grasses. Thus, a large number of endophytes were found in warm-season grasses and could enhance plant growth or grass nitrogen levels by using nitrogen fixation. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2023.

Effect of Poultry Litter Application Method and Rainfall and Delayed Wrapping on Warm-Season Grass Baleage

Poultry litter is a widely available fertilizer in the southeast USA and subsurface application of litter can increase both forage production and nutritive value. Frequent rainfall events and high humidity often limit time available for hay curing; baled silage techniques can increase harvest time flexibility. Unfortunately, rainfall events can still occur without forecast during harvest events, resulting in delayed baling or wrapping. The objective of this study was to evaluate poultry litter amendment methods, subsurface (SUB) and surface (SURF), and the effect of no rain (NR) on bales with wrapping after 2 h compared with rained-on bales with 17 h delayed wrapping (RDW) on warm-season grass baleage fermentation and nutritive value. Data were analyzed as a randomized complete block design with two amendment treatments and two post-baling treatments. Crude protein (CP) was greater (p < 0.01) and neutral detergent fiber (NDF) was lower (p < 0.01) in both pre- and post-ensiled bales with subsurface-applied poultry litter. Rain and delayed wrapping resulted in lower pH (p = 0.03), starch (p < 0.01), and water-soluble carbohydrates (p < 0.01) in pre-ensiled bales, compared to those that did not receive rain and were wrapped within 2 h, while post-ensiled bales only differed in lower (p < 0.01) starch and slightly greater (p < 0.01) NDF in RDW. Lactic acid (p < 0.01), acetic acid (p < 0.01), and total acids (p = 0.03) were greater in SUB, while butyric acid tended to be greater (p = 0.09), and alcohols (p = 0.05) were greater in SURF. Bales from RDW and NR only differed by greater (p < 0.01) propionic acid concentrations in NR. Under the conditions of this experiment, subsurface application of poultry litter increased final nutritive value, while rainfall and delayed wrapping of 17 h had few effects on the final nutritive value of warm-season grass baleage.

Mesquites Limit Targeted Grazing Effects on Texas Wintergrass Growth and Reproduction Responses

In mixed C3/C4 grasslands of the southern Great Plains of North America, honey mesquite (Prosopis glandulosa Torr.) invasion facilitates the dominance of the C3 midgrass Texas wintergrass (Nassella leucotricha [Trin. & Rupr.] Pohl) to the detriment of warm-season grasses. Little is known about the viability of targeted grazing as a treatment method for reducing Texas wintergrass biomass and reproduction, particularly under mesquite canopies. We quantified the effects of targeted grazing treatments (grazed once [G1], grazed twice [G2], and control) and mesquite canopy position (under canopy [UC] and outside of canopy [OC]) on Texas wintergrass basal area, total dry matter (DMY) per basal area, live DMY per basal area, dead DMY per basal area, leaf length, total number of reproductive culms per plant, number of fungus-infected reproductive culms per plant, and rate of reproductive culm development over 2 yr at two study sites. Targeted grazing reduced leaf length and biomass and slowed reproductive development of the wintergrass plants that cattle could more easily access. Environmental factors and differences in mesquite physiognomy at the two study sites likely interacted with grazing treatments, making it challenging to separate the impacts of targeted grazing treatments from other factors. Results suggest mesquite removal is likely necessary to increase cattle access to Texas wintergrass, particularly in stands with multistemmed trees.

Drought Stress Responses of Some Prairie Landscape C4 Grass Species for Xeric Urban Applications

Creating xeric landscapes in lawns and prairies is a significant challenge and practical need in arid urban environments. This study examined the drought resistance of some C4 grass species for constructing urban lawns and prairies. A factorial experiment based on randomized complete block designs with four replications was conducted. Experimental treatments were two irrigation levels (100% and 50% Field Capacity (FC)) and five warm-season grass species (Andropogon gerardii Vitman, Sorghastrum nutans (L.) Nash, Panicum virgatum L., Schizachyrium scoparium (Michx.) Nash, and Bouteloua curtipendula (Michx.) Torr.). The effects of drought on physiological, morphological, and qualitative characteristics of the grass species were analyzed. Drought conditions induced a decrease in all the measured traits. However, fewer physiological, morphological, and qualitative characteristics were affected by drought stress on Andropogon gerardii, Schizachyrium scoparium, and Bouteloua curtipendula, compared to the other two species. Overall, warm-season grasses of Andropogon gerardii, Schizachyrium scoparium, and Bouteloua curtipendula, had greater adaptability to drought stress, making them promising C4 grass species for prairie or lawn landscaping in arid urban environments. Landscape professionals and decision-makers should consider using Andropogon gerardii, Schizachyrium scoparium, and Bouteloua curtipendula, as these were the most resilient grass species for drought-tolerant prairie landscaping schemes. Sorghastrum nutans and Panicum virgatum may be used as a second priority if a more diverse variety of grasses is required for drought-resilient prairie or lawn landscaping in arid cities.

Near-Term Effects of Perennial Grasses on Soil Carbon and Nitrogen in Eastern Nebraska

Incorporating native perennial grasses adjacent to annual row crop systems managed on marginal lands can increase system resiliency by diversifying food and energy production. This study evaluated (1) soil organic C (SOC) and total N stocks (TN) under warm-season grass (WSG) monocultures and a low diversity mixture compared to an adjacent no-till continuous-corn system, and (2) WSG total above-ground biomass (AGB) in response to two levels of N fertilization from 2012 to 2017 in eastern Nebraska, USA. The WSG treatments consisted of (1) switchgrass (SWG), (2) big bluestem (BGB), and (3) low-diversity grass mixture (LDM; big bluestem, Indiangrass, and sideoat grama). Soils were sampled at fixed depth increments (0–120 cm) in the WSG plots and in the adjacent corn experiment in 2012 and 2017. Soil stocks (Mg ha−1) of SOC and TN were calculated on an equivalent soil mass (ESM) basis and compared within the three WSG treatments as well as between experiments (corn compared to the mean of all WSGs). Soil organic C and TN stocks within soil layers and cumulative stocks responded to the main effect of WSG (PWSG < 0.05) but were no different when comparing the WSGs to corn (Pexpt = NS). Both SOC/TN stocks and cumulative stocks were generally greater in the LDM compared to the BGB. Neither SOC nor TN changed over time under either the WSGs or corn. Warm-season grass AGB responded to a three-way interaction of year, N rate, and WSG (p = 0.0007). Decreases in AGB over time were significant across WSGs and N levels except for SWG at 56 kg N ha−1 and LDM at 112 kg N ha−1. Above-ground biomass was generally greater in the LDM after the first harvest year (2013). Results suggest that incorporating WSGs into marginal cropland can maintain SOC and TN stocks while providing a significant source of biomass to be used in energy production or in integrated livestock systems.