Warm-season Grasses Research Articles

128 Effects of Cottonseed Meal Supplementation Strategy to Stocker Calves Grazing Late Season Summer Forage

Abstract Summer stocker calves grazing perennial warm-season grasses may benefit from protein supplementation due to the low protein content typically observed in these forages. Cottonseed meal (CSM) is an excellent protein supplement that is readily available in the south and is competitively priced per unit of protein in early summer. However, research regarding the effects of CSM supplementation level and frequency on calf gain and composition of gain is limited. It was hypothesized that supplementing CSM to grazing heifers would improve ADG and perhaps alter composition of gain when compared with non-supplemented heifers. Objectives for this experiment were to 1) compare gain and composition of gain between calves supplemented with CSM to non-supplemented calves, and 2) compare the effect of daily vs. alternating days of CSM supplementation. A total of 27 commercial Angus beef heifers weighing 234.1 ± 4.18 kg were blocked by BW (light, medium, and heavy) and allocated to 9 paddocks of W.W. B-Dahl Bluestem (Bothriochloa bladhii) for 67 d. The experimental was designed as a RCBD with 3×3 factorial arrangement of 3 treatments and 3 weight blocks. Heifers were supplemented daily with a mineral mix and either no cottonseed meal (CON), 454 g/animal of CSM daily (CSM1), or 909 g/animal of CSM every other day (CSM2). Initial and final shrunk BW was measured, and total gain, ADG, and percent of BW gained were calculated. Ultrasound of initial and final longissimus muscle area (LMA), backfat (BF), and intramuscular fat (IMF) were measured. There were no treatment by block interactions for any measured variable. Treatment significantly affected total gain and ADG (P = 0.0156), as well as percent of BW gain (P = 0.029). Heifers receiving CSM1 treatment gained 28.3% more total BW than heifers receiving CON (47.27 vs. 36.82 kg, respectively) and CSM2 was intermediate (42.73 kg). Likewise, percent of BW gained was greatest for CSM1 and least for CON (16.9 vs.3.8% of initial BW), with CSM2 not differing (15.5% of initial BW). Treatment did not affect the composition of gain (P ≥ 0.190); however, block tended (P = 0.0812) to affect LMA % gain, with light heifers being greater than medium and heavy heifers (12.00% vs. 7.35% and 5.09% increase, respectively). As expected, heifers grazing late summer W.W. B-Dahl Bluestem forage who received 454 g of CSM daily had significantly greater ADG than heifers not receiving CSM. Heifers receiving 909 g of CSM every other day tended to gain more than heifers not receiving CSM, but replication of this experiment is needed for validation of this specific supplementation strategy. In conclusion, supplementation of CSM to calves grazing low protein summer forage within a limited period may have positive measurable effects on gain.

Compensatory Structural Growth Responses of Early-Succession Native Warm-Season Grass Stands to Defoliation Management

There is a growing recognition of the significance of unique morphological and physiological adaptation of native warm-season grasses (NWSG) of North America as summer forage resources and major grassland ecosystem components. Defoliation management plays a major role in ensuring eco-friendly utilization of grassland natural resources. To assess sward structural responses of big bluestem (BB, Andropogon gerardii Vitman), eastern gamagrass (GG, Tripsacum dactyloides L.), indiangrass (IG, Sorghastrum nutans L. Nash), and switchgrass (SG, Panicum virgatum L.) stands to seasonal changes in harvest regimes, a five-year forage harvesting trial was conducted, in a randomized complete block design, at Virginia State University’s research farm. Vegetation structural response attributes (sward-height, canopy closure, stand density and basal cover) of newly established the NWSG stands to second year changes in harvest regimes were monitored. In 2013, 64 plots of year-old stands of transplanted BB, GG, IG, and SG separated by ≥120-cm alleys were cut once in early-August and mid-November to suppress weeds and promote tillering. Starting June 2014, each plot had three 1.5-m wide side-by-side harvest-strips cut once-, twice-, or thrice year−1 (frequencies) ending mid-Oct for four consecutive years followed by a single mid-summer harvest in 26 June 2018, using a forage plot-harvester. In 2015, harvest frequencies for the three- and single-cut strips, in plots 32–64, were switched/flipped once and never reverted. Data was recorded on four early-summer and late-fall sward heights, from each strip at 60-cm intervals before the first and the last harvest, each year. early-spring basal- and canopy-diameter, for mid-April 2015 and 2016, concurrent early-spring canopy light interception, using the LI-191 Line Quantum Sensor, and season-end visual obstruction heights, for stand density in 2016 and 2017. All regrowth sward-heights showed effects of harvest frequency and exhibited compensatory structural responses to the change in harvest regimes. Basal and canopy diameters tended to be greater for the single-cut strips that were previously cut thrice.

Patch Burning Improves Nutritional Quality of Two Gulf Coast Grasses—And Winter Burning Is Better than Summer Burning

Gulf cordgrass (Spartina spartinae [Trin.] Merr. ex Hitchc.) and seacoast bluestem (Schizachyrium scoparium [Michx.] Nash var. littorale [Nash] Gould) are dominant native warm season grasses in the Texas Coastal Prairies and Marshes ecoregion. Mature Gulf cordgrass nutritive value is considered poor for grazing animals, while seacoast bluestem nutritive value is considered fair to good in spring and early summer. We compared season of burn effects on crude protein (CP) and neutral detergent fiber (NDF) of these grasses. Our study employed four patches (200–305 ha) burned in a patch-burn grazing system (two winter, two summer 2016). Forage samples were collected before burning and every 3 d for 40 d after burning, then weekly for 50 d. Regardless of season of burning, CP was adequate for maintaining a lactating beef cow 90 d post-burning. Although peak CP in Gulf cordgrass following burning did not differ between seasons, CP increased more quickly following winter burning, when it rose abruptly for ~6.4 d and then increased more slowly to its peak at ~30 d post burn, after which it declined. After summer burning, CP of Gulf cordgrass did not increase significantly, and then declined after reaching its peak at ~29 d post burn. Gulf cordgrass NDF declined more rapidly following summer burning than winter burning but remained low for a longer period after winter burning. In seacoast bluestem, CP increased following winter burning, peaking at ~11 d after burning, but there was little change following summer burning, which did not peak until 31 d post burn. NDF of seacoast bluestem declined similarly in both seasons. This study indicates that prescribed fire during winter is more beneficial for improving the nutritive value of Gulf cordgrass and seacoast bluestem than summer burning.

Fecal Microbiota, Forage Nutrients, and Metabolic Responses of Horses Grazing Warm- and Cool-Season Grass Pastures

Integrating warm-season grasses into cool-season equine grazing systems can increase pasture availability during summer months. The objective of this study was to evaluate effects of this management strategy on the fecal microbiome and relationships between fecal microbiota, forage nutrients, and metabolic responses of grazing horses. Fecal samples were collected from 8 mares after grazing cool-season pasture in spring, warm-season pasture in summer, and cool-season pasture in fall as well as after adaptation to standardized hay diets prior to spring grazing and at the end of the grazing season. Random forest classification was able to predict forage type based on microbial composition (accuracy: 0.90 ± 0.09); regression predicted forage crude protein (CP) and non-structural carbohydrate (NSC) concentrations (p < 0.0001). Akkermansia and Clostridium butyricum were enriched in horses grazing warm-season pasture and were positively correlated with CP and negatively with NSC; Clostridum butyricum was negatively correlated with peak plasma glucose concentrations following oral sugar tests (p ≤ 0.05). These results indicate that distinct shifts in the equine fecal microbiota occur in response different forages. Based on relationships identified between the microbiota, forage nutrients, and metabolic responses, further research should focus on the roles of Akkermansia spp. and Clostridium butyricum within the equine hindgut.

Salt-responsive bermudagrass microRNAs and insights into light reaction photosynthetic performance.

Bermudagrass (Cynodon dactylon L.) is a warm-season grass with high drought and salt tolerance. However, its cultivation as a silage crop is limited by its lower forage value when compared to other C4 crops. Because of its high genetic variability in abiotic stress tolerance, bermudagrass-mediated genetic breeding offers significant promise for introducing alternative fodder crops in saline and drought-affected regions, and improved photosynthetic capacity is one way for increasing forage yield. Here, we used RNA sequencing to profile miRNAs in two bermudagrass genotypes with contrasting salt tolerance growing under saline conditions. Putatively, 536 miRNA variants were salt-inducible, with the majority being downregulated in salt-tolerant vs sensitive varieties. Also, seven miRNAs putatively targeted 6 genes which were significantly annotated to light reaction photosynthesis. Among the microRNAs, highly abundant miRNA171f in the salt tolerant regime targeted Pentatricopeptide repeat-containing protein and dehydrogenase family 3 member F1 both annotated to electron transport and Light harvesting protein complex 1 genes annotated to light photosynthetic reaction in salt tolerant regime vs salt sensitive counterparts. To facilitate genetic breeding for photosynthetic capacity, we overexpressed miR171f in Medicago tracantula which resulted in a substantial increase in the chlorophyll transient curve, electron transport rate, quantum yield of photosystem II non photochemical quenching, NADPH and biomass accumulation under saline conditions while its targets were downregulated. At ambient light level the electron transport was negatively correlated with all parameters while the NADPH was positively associated higher dry matter in mutants. These results demonstrate that miR171f improves photosynthetic performance and dry matter accumulation via transcriptional repression of genes in the electron transport pathway under saline conditions and thus a target for breeding.

Molecular Mechanism of Cold Tolerance of Centipedegrass Based on the Transcriptome.

Low temperature is an important limiting factor in the environment that affects the distribution, growth and development of warm-season grasses. Transcriptome sequencing has been widely used to mine candidate genes under low-temperature stress and other abiotic stresses. However, the molecular mechanism of centipedegrass in response to low-temperature stress was rarely reported. To understand the molecular mechanism of centipedegrass in response to low-temperature stress, we measured physiological indicators and sequenced the transcriptome of centipedegrass under different stress durations. Under cold stress, the SS content and APX activity of centipedegrass increased while the SOD activity decreased; the CAT activity, POD activity and flavonoid content first increased and then decreased; and the GSH-Px activity first decreased and then increased. Using full-length transcriptome and second-generation sequencing, we obtained 38.76 G subreads. These reads were integrated into 177,178 isoforms, and 885 differentially expressed transcripts were obtained. The expression of AUX_IAA and WRKY transcription factors and HSF transcription-influencing factors increased during cold stress. Through KEGG enrichment analysis, we determined that arginine and proline metabolism, plant circadian rhythm, plant hormone signal transduction and the flavonoid biosynthesis pathways played important roles in the cold stress resistance of centipedegrass. In addition, by using weighted gene coexpression network analysis (WGCNA), we determined that the turquoise module was significantly correlated with SS content and APX activity, while the blue module was significantly negatively correlated with POD and CAT activity. This paper is the first to report the response of centipedegrass to cold stress at the transcriptome level. Our results help to clarify the molecular mechanisms underlying the cold tolerance of warm-season grasses.

Response of Warm Season Turf Grasses to Combined Cold and Salinity Stress under Foliar Applying Organic and Inorganic Amendments

Turfgrasses are considered an important part of the landscape and ecological system of golf courses, sports fields, parks, and home lawns. Turfgrass species are affected by many abiotic stresses (e.g., drought, salinity, cold, heat, waterlogging, and heavy metals) and biotic stresses (mainly diseases and pests). In the current study, seashore paspalum (Paspalum vaginatum Sw.) and Tifway bermudagrass (Cynodon transvaalensis Burtt Davy × C. Dactylon) were selected because they are popular turfgrasses frequently used for outdoor lawns and sport fields. The effect of the combined stress from both soil salinity and cold on these warm season grasses was investigated. Some selected organic and inorganic amendments (i.e., humic acid, ferrous sulphate, and silicon) were applied as foliar sprays five times during the winter season from late October to March. This was repeated over two years in field trials involving salt-affected soils. The physiological and chemical parameters of the plants, including plant height; fresh and dry weight per plot; total chlorophyll content; and nitrogen, phosphorus, iron, and potassium content, were measured. The results showed that all the studied amendments improved the growth of seashore paspalum and Tifway bermudagrass during this period compared to the control, with a greater improvement observed when using ferrous sulphate and humic acid compared to silicon. For seashore paspalum, the highest chlorophyll content in April was recorded after the application of ferrous sulphate at a level of 1000 ppm. The current research indicates that when grown on salt-affected soils, these amendments can be used in warm-season grasses to maintain turf quality during cold periods of the year. Further research is needed to examine any negative long-term effects of these amendments and to explain their mechanisms.

Evaluation of Grazing Options During Summer for Growing Heifers – Year 3

Developing methods to provide high quality forage through most of the year is important for cattle operations. The purpose of this study was to determine forage management options to offset the summer “slump” with fescue. Four grass pasture treatments (10 pastures total; 4 acres each) were used in a completely randomized design and stocked with growing heifers (n = 49; initial wt 461 ± 65 lb). Pasture treatments consisted of novel fescue (FES), crabgrass (CRAB), bermudagrass (BERM), and sorghum-sudan interseeded into novel fescue (SS-FES). Heifers were weighed and they grazed pastures from May to September. Heifers on FES were continuously grazed. All other pastures were rotationally grazed. Sorghum-sudan was interseeded into fescue pastures in May. Average daily gain (ADG) for the entire grazing period was not different between pasture systems. Heifers on BERM and SS-FES had greater gain per acre than those FES pastures, with CRAB being intermediate. This result was primarily based on the increased stocking rates for those pastures. The extreme drought during the summer of 2022 resulted in little to no production of the sorghum-sudan and these pastures had the lowest biomass through the grazing period. Moisture is essential for success of interseeding sorghum-sudan into fescue pastures. Weather patterns impact animal performance as it impacts forage production. The best management practice may involve operations that have a variety of cool and warm-season grasses that producers can use to optimize forage production through varying weather events.

Ring‐necked pheasant nest site selection in a landscape with high adoption of fall‐seeded cover crops

AbstractGrasslands provide important nesting cover for ring‐necked pheasants (Phasianus colchicus), but they have been largely reduced with intensification of row‐cropping systems, resulting in population declines for pheasants and other grassland birds across the U.S. Row‐crop intensification and landscape homogenization has had negative impacts on environmental health, and agronomic practices such as fall‐seeded cover crops seek to ameliorate some of the environmental issues. Whether fall‐seeded cover crops provide additional benefits to wildlife, such as creating nesting cover for pheasants, remains unknown. We used radio telemetry and nest searches in 365, 0.4‐ha² plots during summer of 2019 and 2020 in 3 cover types including fall‐seeded cover crops, native warm season grasses, and cool season grasses to examine nest site selection by pheasants in the agricultural dominated landscape of Washington County, Iowa. We examined nest site selection at 3 spatial scales based on cover type and specific vegetation attributes to understand factors influencing nest site selection. Highest nest densities were found in native warm season grass (0.59 nests/ha, 95% CI = 0.41–0.86), while pheasants nested at low densities in cool season grass fields (0.03 nests/ha, 95% CI = 0.00–0.21) and cover crop fields (0.03 nests/ha, 95% CI = 0.01–0.12). Most nest‐site selection occurred at the landscape level (second order) and patch level (third order) and was influenced by percent litter cover (second order) and visual obstruction or vegetation density (third order). Our findings suggest that cover crops may make minor improvements in nesting cover availability but are unlikely to replicate the needs for nesting cover provided by perennial grasslands in working landscapes and thus have little potential to reverse long‐term population declines.

Compensatory Yield Responses of Young Native Warm-Season Grass Stands to Seasonal Changes in Harvest Frequencies

Defoliation management can significantly affect subsequent grassland’s forage productivity and sustainability. To assess the type and persistence of native warm-season grass (NWSG) yield responses to changes in defoliation intensity, a five-year harvest trial was conducted, in a randomized complete block design, at Virginia State University’s research farm. Yield responses of newly established indiangrass (Sorghastrum nutans L.). Nash, big bluestem (Andropogon gerardii Vitman), switchgrass (Panicum virgatum L.) and eastern gamagrass (Tripsacum dactyloides L.) stands to second-year changes in harvest regimes were monitored. In 2012, seedlings of these native grasses were transplanted in clean-tilled plots, with 16 plants in each pot. The field was not irrigated, but broadleaf weeds were manually controlled, and all plots were mowed in August and mid-November of 2013. Starting June 2014, each plot had three harvest-strips assigned to single, two, or three cuts per year from early June to mid-October using a plot-harvester; forage weights were recorded. Based on the recorded fresh and oven-dry sample weights, plot forage DM yields were estimated. Cumulative forage biomass of all three-cut strips flipped to single-cut increased by ≥30% and &gt;50% for big bluestem. The second-year single-cut yields also outperformed those cut thrice since the first year by 22–51%. The second-year biomass increases from single-cut strips that were cut thrice in the first year demonstrated that flipping-triggered compensatory yield responses overshadowed the first- year losses in plant vigor. The compensatory yield increases continued to, but not beyond, the third year and varied between species. The yield responses also showed that magnitudes of defoliation management–triggered NWSG growth responses depend more on growing conditions during the recovery period than its actual duration.

Leaf Mycobiome and Mycotoxin Profile of Warm-Season Grasses Structured by Plant Species, Geography, and Apparent Black-Stroma Fungal Structure.

Grasses harbor diverse fungi, including some that produce mycotoxins or other secondary metabolites. Recently, Florida cattle farmers reported cattle illness, while the cattle were grazing on warm-season grass pastures, that was not attributable to common causes, such as nutritional imbalances or nitrate toxicity. To understand correlations between grass mycobiome and mycotoxin production, we investigated the mycobiomes associated with five prominent, perennial forage and weed grasses [Paspalum notatum Flügge, Cynodon dactylon (L.) Pers., Paspalum nicorae Parodi, Sporobolus indicus (L.) R. Br., and Andropogon virginicus (L.)] collected from six Florida pastures actively grazed by livestock. Black fungal stromata of Myriogenospora and Balansia were observed on P. notatum and S. indicus leaves and were investigated. High-throughput amplicon sequencing was applied to delineate leaf mycobiomes. Mycotoxins from P. notatum leaves were inspected using liquid chromatography-mass spectrometry (LC-MS/MS). Grass species, cultivars, and geographic localities interactively affected fungal community assemblies of asymptomatic leaves. Among the grass species, the greatest fungal richness was detected in the weed S. indicus. The black fungal structures of P. notatum leaves were dominated by the genus Myriogenospora, while those of S. indicus were codominated by the genus Balansia and a hypermycoparasitic fungus of the genus Clonostachys. When comparing mycotoxins detected in P. notatum leaves with and without M. atramentosa, emodin, an anthraquinone, was the only compound which was significantly different (P < 0.05). Understanding the leaf mycobiome and the mycotoxins it may produce in warm-season grasses has important implications for how these associations lead to secondary metabolite production and their subsequent impact on animal health. IMPORTANCE The leaf mycobiome of forage grasses can have a major impact on their mycotoxin contents of forage and subsequently affect livestock health. Despite the importance of the cattle industry in warm-climate regions, such as Florida, studies have been primarily limited to temperate forage systems. Our study provides a holistic view of leaf fungi considering epibiotic, endophytic, and hypermycoparasitic associations with five perennial, warm-season forage and weed grasses. We highlight that plant identity and geographic location interactively affect leaf fungal community composition. Yeasts appeared to be an overlooked fungal group in healthy forage mycobiomes. Furthermore, we detected high emodin quantities in the leaves of a widely planted forage species (P. notatum) whenever epibiotic fungi occurred. Our study demonstrated the importance of identifying fungal communities, ecological roles, and secondary metabolites in perennial, warm-season grasses and their potential for interfering with livestock health.

Genome-wide analysis of tandem duplicated genes and their expression under salt stress in seashore paspalum

Seashore paspalum (Paspalum vaginatum) is a halophytic, warm-season grass which is closely related to various grain crops. Gene duplication plays an important role in plant evolution, conferring significant plant adaptation at the genomic level. Here, we identified 2,542 tandem duplicated genes (TDGs) in the P. vaginatum genome and estimated the divergence time of pairs of TDGs based on synonymous substitution rates (Ks). Expression of P. vaginatum TDGs resulted in enrichment in many GO terms and KEGG pathways when compared to four other closely-related species. The GO terms included: “ion transmembrane transporter activity,” “anion transmembrane transporter activity” and “cation transmembrane transport,” and KEGG pathways included “ABC transport.” RNA-seq analysis of TDGs showed tissue-specific expression under salt stress, and we speculated that P. vaginatum leaves became adapted to salt stress in the earlier whole-genome duplication (WGD; ~83.3 million years ago; Ma), whereas the entire P. vaginatum plant acquired a large number of TDGs related to salt stress in the second WGD (~23.3 Ma). These results can be used as a reference resource to accelerate salt-resistance research in other grasses and crops.

Evaluation of the tolerance and forage quality of different ecotypes of seashore paspalum.

Seashore paspalum is a halophytic, warm-season grass with wide applications. It is noted for its superior salt tolerance in saline environments; however, the nutritive value of seashore paspalum and the effect of salinity remains to be determined. Therefore, this study aimed to evaluate the relationship between agronomic traits and forage quality and identified the effects of short-term high-salt stress (1 week, 700 mM NaCl) on the growth and forage nutritive value of 16 ecotypes of seashore paspalum. The salt and cold tolerances of the seashore paspalum ecotypes were assessed based on the survival rate following long-term high-salt stress (7 weeks, 700 mM NaCl) and exposure to natural low temperature stress. There were significant genetic (ecotype-specific) effects on plant height, leaf–stem ratio, and survival rate of seashore paspalum following salt or low temperature stress. Plant height was significantly negatively correlated with the leaf–stem ratio (r = −0.63, P<0.01), but the heights and leaf–stem ratios were not significantly correlated with the fresh weight (FW) and dry weight (DW) of the shoots. High salinity decreased the FW and DW of the shoots by 50.6% and 23.6%, respectively, on average. Seashore paspalum exhibited outstanding salt tolerance and forage quality at high salinity. The survival rate of the different ecotypes of seashore paspalum varied from 6.5% to 49.0% following treatment with 700 mM NaCl for 7 weeks. The crude protein (CP) content of the control and treatment groups (700 mM NaCl) was 17.4% and 19.3%, respectively, of the DW on average, and the CP content of most ecotypes was not significantly influenced by high salinity. The average ether extract (EE) content ranged from 4.6% to 4.4% of the DW under control and saline conditions, respectively, indicating that the influence was not significant. The neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents of the control group were 57.4% and 29.8%, respectively, of the DW on average. Salt stress reduced the content of NDF and ADF to 50.2% and 25.9%, respectively, of the DW on average. Altogether, the results demonstrated that stress did not have any significant effects on the CP and EE content of most ecotypes, but reduced the NDF and ADF content and improved relative feed value (RFV). The results obtained herein support the notion that seashore paspalum is a good candidate for improving the forage potential of saline soils and can provide useful guidelines for livestock producers.

Effects of grazing strategy on facultative grassland bird nesting on native grassland pastures of the Mid-South USA.

Understanding how livestock grazing strategies of native warm season grasses (NWSG) can impact facultative grassland bird nesting can provide insight for conservation efforts. We compared pre and post treatment effects of rotational grazing (ROT) and patch-burn grazing (PBG) for facultative grassland bird species nest success and nest-site selection on NWSG pastures at three Mid-South research sites. We established 14, 9.7 ha NWSG pastures and randomly assigned each to either ROT or PBG and monitored avian nest-site selection and nest success, 2014–2016. We collected nesting and vegetation data in 2014, before treatment implementation, as an experimental pre-treatment. We implemented treatments across all research sites in spring 2015. We used a step-wise model selection framework to estimate treatment effect for ROT or PBG on avian nest daily survival rate (DSR) and resource selection function (RSF) at the temporal scale and within-field variables. Daily survival rates were 0.93% (SE = 0.006) for field sparrow (Spizella pusilla), 0.96% (SE = 0.008) for red-winged blackbird (Agelaius phoeniceus), and 0.92% (SE = 0.01) for indigo bunting (Passerina cyanea). Model support for PBG treatment and vegetation height were indicated as negative and positive influences for field sparrow DSR, respectively. Red-winged blackbirds’ DSR were negatively influenced by ROT while vegetation height positively affected DSR, and DSR for indigo bunting did not differ among treatments. Combined RSF models indicated nest-site selection for all species was positively related to vegetation height and only weakly associated with other within-field variables. We provide evidence that ROT and/or PBG effects vary by species for DSR for these three facultative grassland birds, and vegetation characteristics affected their nest-site selection in the Mid-South USA. A lack of disturbance in Mid-South grasslands can lead to higher successional stages (i.e., mix shrub-grassland), but some combination of ROT, PBG, and unburned/ungrazed areas can provide adequate nesting habitat on small pasture lands (∼1.8 –7.8 ha) for various facultative grassland birds and potentially offer the opportunity to simultaneously maintain livestock production and grassland bird nesting habitat.

A Novel Beta-Glucosidase Gene for Plant Type Was Identified by Genome-Wide Association Study and Gene Co-Expression Analysis in Widespread Bermudagrass.

Bermudagrass (Cynodon spp.) is one of the most widely distributed warm-season grasses globally. The growth habits and plant type of bermudagrass are strongly associated with the applied purpose of the landscape, livestock, and eco-remediation. Therefore, persistent efforts are made to investigate the genetic basis of plant type and growth habits of bermudagrass. Here, we dissect the genetic diversity of 91 wild bermudagrass resources by genome-wide association studies (GWAS) combined with weighted gene co-expression analysis (WGCNA). This work is based on the RNA-seq data and the genome of African bermudagrass (Cynodon transvaalensis Burtt Davy). Sixteen reliable single-nucleotide polymorphisms (SNPs) in transcribed regions were identified to be associated with the plant height and IAA content in diverse bermudagrass by GWAS. The integration of the results from WGCNA indicates that beta-glucosidase 31 (CdBGLU31) is a candidate gene underlying a G/A SNP signal. Furthermore, both qRT-PCR and correlation coefficient analyses indicate that CdBGLU31 might play a comprehensive role in plant height and IAA biosynthesis and signal. In addition, we observe lower plant height in Arabidopsis bglu11 mutants (homologs of CdBGLU31). It uncovers the breeding selection history of different plant types from diverse bermudagrass and provides new insights into the molecular function of CdBGLU31 both in plant types and in IAA biosynthetic pathways.

Perennial Warm-Season Grass Forages Impact on Cow-Calf Profitability in the Fescue Belt

Incorporating a perennial warm- season grass (WSG) into tall fescue (Lolium arundina-ceum [Schreb.] Darbysh.) forage systems in the fescue belt can help avoid the effects of fescue toxicosis on beef cattle (Bos taurus) reproduction and animal performance and provide forage during summer when fescue production is low. However, little information is available on the economics of incorporating WSG into fescue-based forage systems. We developed a simulation model to compare profitability of three forage systems—100% tall fescue, 70% tall fescue/30% bermudagrass (Cynodon dactylon), and 70% tall fescue/ 30% switchgrass (Panicum virgatum)—while also comparing spring- and fall-calving sea-sons on model beef cattle cow-calf operations in the fescue belt. Incorporating switch-grass increased profitability of tall fescue forage systems in both spring- and fall- calving herds, while adding bermudagrass increased profitability in spring-calving herds but not fall-calving herds. Spring-calving herds benefited the most from incorporating WSG, with profitability increases of $877 and $372 per hectare for switchgrass and bermudagrass, respectively, over the 100% tall fescue system. The order of profitability of forage systems did not change with randomly simulated decreases in rainfall and associated increased hay- feeding days, but with annual rainfall >88% of the long- term average, fall- calving 100% tall fescue was more profitable than fall- calving 70% tall fescue/30% bermuda grass. Of the scenarios modeled, the results of the simulation suggest that a profit-maximizing producer would utilize a 70% tall fescue/30% switchgrass forage system.

Bermudagrass Establishment, Aesthetics, and Function in Response to the Microbial Inoculant Klebsiella variicola and Fertilizer Timing

The incorporation of biostimulants, including microbial inoculants, into turfgrass management programs has increased during the past decade as a result of the potential benefits of their use, including increased nutrient uptake, enhanced growth, and improved stress tolerance. However, minimal research has been conducted on warm-season grasses, and questions still exist regarding microbial inoculant application timing, frequency of inoculation, and need for supplemental nitrogen. Therefore, the objective of our research was to investigate the influence of nitrogen fertilizer and microbial inoculant application timings on the establishment of common bermudagrass [Cynodon dactylon (L.) Pers.] in the field and in a controlled environment. Treatments containing fertilizer had a consistently greater normalized difference vegetation index, turfgrass color, and turfgrass quality than treatments that contained only the Klebsiella variicola microbial inoculant (KV). Establishment of bermudagrass plots in response to treatments containing fertilizer had more than 90% cover at the conclusion of the study (8 weeks after seeding), whereas KV treatments and the untreated check never exceeded 70% cover. However, the greatest change in carbon efflux was often observed in the field in response to treatments that supplied KV 3 weeks after seeding. In the greenhouse, the greatest root and shoot weights were typically observed in response to treatments containing fertilizer, whereas KV-alone treatments resulted in root and shoot weights either similar to or less than the untreated check.

Evaluating phytochemical and microbial contributions to atrazine degradation

The inclusion of warm-season grasses, such as switchgrass (Panicum virgatum) and eastern gamagrass (EG) (Tripsacum dactyloides), in vegetated buffer strips has been shown to mitigate herbicide contamination in runoff and increase herbicide degradation in soil. The mode of action by which buffer strip rhizospheres enhance herbicide degradation remains unclear, but microorganisms and phytochemicals are believed to facilitate degradation processes. The objectives of this study were to: 1) screen root extracts from seven switchgrass cultivars for the ability to degrade the herbicide atrazine (ATZ) in solution; 2) determine sorption coefficients (Kd) of the ATZ-degrading phytochemical 2-β-D-glucopyranosyloxy-4-hydroxy-1,4-benzoxazin-3-one (DBG) to soil and Ca-montmorillonite, and investigate if DBG or ATZ sorption alters degradation processes; and 3) quantify ATZ degradation rates and soil microbial response to ATZ application in mesocosms containing soil and select warm-season grasses. Phytochemicals extracted from the roots of switchgrass cultivars degraded 44–85% of ATZ in 16-h laboratory assays, demonstrating that some switchgrass cultivars could rapidly degrade ATZ under laboratory conditions. However, attempts to isolate ATZ-degrading phytochemicals from plant roots were unsuccessful. Sorption studies revealed that DBG was strongly sorbed to soil (Kd = 87.2 L kg−1) and Ca-montmorillonite (Kd = 31.7 L kg−1), and DBG driven hydrolysis of ATZ was entirely inhibited when either ATZ or DBG were sorbed to Ca-montmorillonite. Atrazine degradation rates in mesocosm soils were rapid (t0.5 = 8.2–11.2 d), but not significantly different between soils collected from the two switchgrass cultivar mesocosms, the eastern gamagrass cultivar mesocosm, and the unvegetated mesocosm (control). Significant changes in three phospholipid fatty acid biomarkers were observed among the treatments. These changes indicated that different ATZ-degrading microbial consortia resulted in equivalent ATZ degradation rates between treatments. Results demonstrated that soil microbial response was the dominant mechanism controlling ATZ degradation in the soil studied, rather than root phytochemicals.

KR bluestem (Bothriochloa ischaemum var. songarica) has some direct allelopathic effects on germination but not on seedling growth in a native/non-native mixed community of warm season grasses in Texas

KR bluestem (Bothriochloa ischaemum var. songarica) has some direct allelopathic effects on germination but not on seedling growth in a native/non-native mixed community of warm season grasses in Texas

Growth performance evaluation of Bermuda grass (Cynodon dactylon L. Pers. x Cynodon transvaalensis) under different nitrogen application methods and sprigging intensities

Cynodon dactylon (L.) Pers, commonly called Bermuda grass is one among the most commonly used warm season grasses which can withstand drought stress and produce quality turf. Establishing high quality turf is a key management concern. The selection of suitable method of its establishment and precise nutrient management are the first and most important factors for a well-established lawn. N has the greatest impact on grass growth of all the nutrients, and an appropriate N fertiliser can quicken up the development of high-quality mats. Hence a field trial was conducted at Tamil Nadu Agricultural University, Coimbatore to study the growth response of Bermuda grass to 4 different sprigging intensities: S1- 10×10 cm, S2- 15×15 cm, S3- 20×20 cm, S4- 25×25 cm and 3 different methods of N application at fortnight intervals: N1- Granular application at 4g/m2, N2- 2% Foliar spray and N3- IFFCO Nano Urea at 5ml/l of water. Morphological parameters including leaf length, internodal length, shoot length, root length, percent cover and physiological parameters including total chlorophyll content, relative greenness and proline content for drought estimation have been evaluated at 90 days after planting. Plots treated with nano urea showed improved growth response rather plots treated with granular urea. Closer and medium spacing showed quick grass spread compared to wider spacing. Among 12 treatments, Treatment S1N3 (10 X 10 cm spacing with 5 ml/ l of water Nano Urea Foliar Spray) recorded the highest values for almost all the morphological (Leaf length 3.43 cm, Internodal length 3.63 cm, Shoot length 52.46 cm, Root length 11.51 cm and Percent cover 101.25%) and physiological parameters (TCC 3.42 mg/ g fresh wt., Relative greenness 13.86 and Proline content 2.52 mg/ g of fresh wt.). Future thrust can be relied on such encapsulated slow-release N fertilizer to ease out nitrogen loss concern and improved turf quality.