Season Grasses Research Articles

Evaluation of global warming effects to cool season grass productivity with models

Evaluation of global warming effects to cool season grass productivity with models

High Spatial Resolution Visual Band Imagery Outperforms Medium Resolution Spectral Imagery for Ecosystem Assessment in the Semi-Arid Brazilian Sertão

Semi-arid ecosystems play a key role in global agricultural production, seasonal carbon cycle dynamics, and longer-run climate change. Because semi-arid landscapes are heterogeneous and often sparsely vegetated, repeated and large-scale ecosystem assessments of these regions have to date been impossible. Here, we assess the potential of high-spatial resolution visible band imagery for semi-arid ecosystem mapping. We use WorldView satellite imagery at 0.3–0.5 m resolution to develop a reference data set of nearly 10,000 labeled examples of three classes—trees, shrubs/grasses, and bare land—across 1000 km 2 of the semi-arid Sertão region of northeast Brazil. Using Google Earth Engine, we show that classification with low-spectral but high-spatial resolution input (WorldView) outperforms classification with the full spectral information available from Landsat 30 m resolution imagery as input. Classification with high spatial resolution input improves detection of sparse vegetation and distinction between trees and seasonal shrubs and grasses, two features which are lost at coarser spatial (but higher spectral) resolution input. Our total tree cover estimates for the study area disagree with recent estimates using other methods that may underestimate treecover because they confuse trees with seasonal vegetation (shrubs and grasses). This distinction is important for monitoring seasonal and long-run carbon cycle and ecosystem health. Our results suggest that newer remote sensing products that promise high frequency global coverage at high spatial but lower spectral resolution may offer new possibilities for direct monitoring of the world’s semi-arid ecosystems, and we provide methods that could be scaled to do so.

Dietary exogenous and endogenous abrasives and tooth wear in African buffalo

The potential contribution of exogenous dust and grit and endogenous plant silica to tooth wear of the African buffalo in Kruger National Park was examined. Endogenous silica as percent dry matter on basalt soils (6.58%) was significantly higher than on granite soils (4.41%), and significantly higher in dry season grasses (6.64%) than in wet season grasses (4.41%). Exogenous grit on granite grasses (0.43%) had significantly higher loads than basalt grasses (0.16%) and wet season loads significantly higher (0.50%) than dry season (0.09%) loads. Grasses on granite soils were significantly tougher (0.266 J m-1) than those on basalt soils (0.215 J m-1). Adult buffalo were estimated to consume 10–28 kg per year of exogenous grit and 300–400 kg per year of endogenous silica. First lower buffalo molars are estimated to wear at an average rate of 1.94 mm per year with no significant difference between wear on the different soil types or between sexes. The high silica intake with no observable differences in tooth wear questions the role of silica in tooth wear. It is proposed that there is an interaction between exogenous and endogenous abrasives and that abrasion must be considered more holistically.

Functional traits in cover crop mixtures: Biological nitrogen fixation and multifunctionality

Abstract Cover crop mixtures with complementary plant functional traits including biological nitrogen fixation (BNF) may supply nitrogen (N) to farm fields while simultaneously providing other ecosystem functions such as N retention and weed suppression (i.e., multifunctionality). Understanding variation in these relationships across farms can help advance trait‐based research in agroecology and ecological approaches to nutrient management. This on‐farm experiment explored the contributions of two‐ and three‐species cover crop mixtures, which combined legumes, brassicas and cool season grasses, to ecosystem functions across a gradient of soil fertility levels driven by farm management history. I evaluated the predictions that functional trait diversity of the cover crops would explain variation in multifunctionality, and that legume biomass and BNF within mixtures would be inversely correlated with indicators of soil N availability from organic matter across the farm gradient. Ecosystem functions varied widely across farms. As expected, functional diversity was a significant predictor of multifunctionality, although the relationship was weak. Cover crop mixtures had significantly greater multifunctionality than a cereal rye monoculture, though not at the highest observed levels of each function, indicating trade‐offs among functions. Linear regression models showed that legume biomass and BNF were negatively correlated with soil properties indicative of N availability from soil organic matter, whereas non‐legume and weed biomass were positively correlated with other measures of soil fertility. Synthesis and applications. Cover crop mixtures can increase functional diversity within crop rotations. Designing mixtures with complementary plant traits may be particularly effective for increasing multifunctionality and agroecosystem sustainability. On‐farm research to understand variation in biological nitrogen fixation, which is both a plant trait and a key ecosystem function, across heterogeneous soil conditions, can inform management of soil fertility based on ecological principles.

Genetic diversity and association mapping of forage quality in diverse bermudagrass accessions

Bermudagrass is a warm season grass widely cultivated for turf and fodder. Nonetheless, the grass has poor forage quality because animals that consume it fail to assimilate its organic matter efficiently. Thus, identification of the marker-trait association between simple sequence repeat (SSR) markers and forage-quality-related traits in diverse bermudagrass accessions would enable efficient selection of high forage quality bermudagrass cultivars. Association mapping of 8 forage-related-quality traits with 1474 markers was conducted in 60 diverse bermudagrass accessions from five geographical regions in China. Significant variations in eight phenotypic and physiological traits were observed among the 60 accessions. A total of 1474 alleles were amplified by 104 SSR primers. The average gene diversity and polymorphic information content for the study sample were 0.2097 and 0.1748 respectively. The clustering analysis suggested that geographic origin influenced genetic distances between accessions. A total of 76 markers significantly associated with traits at P < 0.01; 73 with a single trait and 3 with two traits each. Nevertheless, only 41 significant marker-trait associations (MTAs) were observed after Bonferroni test was separately conducted for each trait. Forty-one microsatellites had significant associations with 8 forage-quality-related traits. These markers provide a feasible means of genetically improving forage quality in bermudagrass after further authentication.

Cost-benefit analysis of native warm season grasses for transmission line right-of way revegetation

The rapid reestablishment of vegetation in newly constructed electric transmission line rights-of-way (ROWs) is important for the control of soil erosion and compliance with associated regulations. Following establishment, routine maintenance must be performed to suppress the encroachment of woody vegetation in ROWs to provide for continuous and safe operation of electric transmission lines. Although non-native seed mixes conventionally are used for this purpose in North America, modeling ROW revegetation on locally adapted native communities could reduce longer-term management needs and provide ecological, environmental, and social benefits associated with native systems. We conducted a cost-benefit analysis to determine if ROW revegetation with a seed mix comprised primarily of native herbaceous species could be cost-effective relative to revegetation with a conventional seed mix comprised primarily of exotic herbaceous species. Our analysis synthesized data collected from a feasibility study of ROWs planted with a native seed mix and information obtained from the Tennessee Valley Authority regarding ROW revegetation and maintenance costs. Overall, the cost of revegetation with native species was ∼5% more expensive per unit area than the cost of revegetation exotic species. The degree of reduced long-term maintenance costs to make revegetation with native species a worthwhile longer-term investment would be 10–17% using a break-even analysis. Despite the initial greater expense of revegetation with native species, we suggest that associated potential maintenance cost savings and ecological, environmental, and social benefits could favor their use.

Combining models to estimate the impacts of future climate scenarios on feed supply, greenhouse gas emissions and economic performance on dairy farms in Norway

There is a scientific consensus that the future climate change will affect grass and crop dry matter (DM) yields. Such yield changes may entail alterations to farm management practices to fulfill the feed requirements and reduce the farm greenhouse gas (GHG) emissions from dairy farms. While a large number of studies have focused on the impacts of projected climate change on a single farm output (e.g. GHG emissions or economic performance), several attempts have been made to combine bio-economic systems models with GHG accounting frameworks. In this study, we aimed to determine the physical impacts of future climate scenarios on grass and wheat DM yields, and demonstrate the effects such changes in future feed supply may have on farm GHG emissions and decision-making processes. For this purpose, we combined four models: BASGRA and CSM-CERES-Wheat models for simulating forage grass DM and wheat DM grain yields respectively; HolosNor for estimating the farm GHG emissions; and JORDMOD for calculating the impacts of changes in the climate and management on land use and farm economics. Four locations, with varying climate and soil conditions were included in the study: south-east Norway, south-west Norway, central Norway and northern Norway. Simulations were carried out for baseline (1961–1990) and future (2046–2065) climate conditions (projections based on two global climate models and the Special Report on Emissions Scenarios (SRES) A1B GHG emission scenario), and for production conditions with and without a milk quota. The GHG emissions intensities (kilogram carbon dioxide equivalent: kgCO2e emissions per kg fat and protein corrected milk: FPCM) varied between 0.8kg and 1.23kgCO2e(kgFPCM)−1, with the lowest and highest emissions found in central Norway and south-east Norway, respectively. Emission intensities were generally lower under future compared to baseline conditions due mainly to higher future milk yields and to some extent to higher crop yields. The median seasonal above-ground timothy grass yield varied between 11,000kg and 16,000kgDMha−1 and was higher in all projected future climate conditions than in the baseline. The spring wheat grain DM yields simulated for the same weather conditions within each climate projection varied between 2200kg and 6800kgDMha−1. Similarly, the farm profitability as expressed by total national land rents varied between 1900 million Norwegian krone (NOK) for median yields under baseline climate conditions up to 3900 million NOK for median yield under future projected climate conditions.

Occurrence of a subgroup 16SrIII-J phytoplasma in non-symptomatic Brachiaria decumbens cultivated in a grazing area

Brachiaria spp. are the most important and widely used warm season grasses for pasture, but are also important weeds for most economic crops in the tropics. During phytoplasma surveys in pasture fields, asymptomatic plants of Brachiaria decumbens were collected for inspection. Nested PCR detected phytoplasmas in more than 90% of sampled plants. Based on computer-simulated RFLP and a similarity coefficient calculation, a subgroup 16SrIII-J phytoplasma was molecularly characterized. Phylogenetic analysis was consistent with virtual RFLP identification. Representatives of this subgroup have been identified in diverse Brazilian regions encompassing various commercial crops. Our study revealed B. decumbens as a new host and reservoir of 16SrIII-J phytoplasma.

Potencial de produção de sementes de gramíneas para a implantação em gramados

The Paspalum and Axonopus genera are among the main warm season grasses used for lawns. The seed propagation contributes to the decrease of the cost of establishment, besides maintaining the exact characteristics of the mother plant genotype, because they are apomictic species. The objective of this work was to evaluate the seed production potential of seventeen grass accesses of the species Paspalum notatum, P. lepton, P. lividum and Axonopus parodii. The experiment was conducted at Capão do Leão, Rio Grande do Sul State, Brazil, in a randomized block design, with four replications. The evaluated variables were: number of inflorescences per area, number of florets per inflorescence and seed production potential (SPP). In order to measure the seed production potential of the accesses, the equation proposed is: SPP = number of florets per inflorescence x number of inflorescences per m2 . There were year, access and interaction between years and accesses effect for the traits number of inflorescences per area and seed production potential. For the number of florets per inflorescence, there was no year effect. Potential production for the 2013/2014 harvest, ranged from 19,152.00 to 135,062.70 seeds m- ², with PN 09 of the P. notatum species standing out. In the 2014/2015 harvest, the seed production potential ranged from 9,973.75 to 81,536.75 seeds m- ², highlighting the access PN 11 of the species P. notatum. The accesses PN 11, PN 09, PN 10 and AP 01 were in the top third of the seed production potential ranking in the two harvests, and “grama-batatais” was in the lower third. There is genotype-environment interaction for all characteristics evaluated. However, there are accesses that show seed production potential consistently superior to the “grama-batatais” control, and have a greater potential for exploitation in the establishment of lawns by seeds.

Salt Tolerance and K/Na Ratio of Some Introduced Forage Grass Species Under Salinity Stress in Irrigated Areas

ABSTRACTSalinity is a limiting factor for forage productivity in irrigated areas. The aim of this study was to evaluate the salt tolerance index (STI), the K/Na ratio, and the forage quality of several introduced cool season grass species in irrigated agriculture. Four irrigated water salinity concentrations were used (control, 4000, 8000, and 12000 ppm sodium chloride (NaCl)), and four grass cultivars belonging to three species were established under greenhouse conditions at the Qassim University Agricultural Research and Experimental Station during the 2012 and 2013 growing seasons (perennial ryegrass (Lolium perenne L., cvs. Aries and Quartet), endophyte-free tall fescue (Festuca arundinacea Schreb., cv. Fawn), and orchardgrass (Dactylis glomerata L., cv. Tekapo)). A randomized complete block design (RCBD) using three replications was used. Cultivars were evaluated based on their dry weights (g m−2) and forage quality. Additionally, the STI and potassium (K+) and sodium (Na+) concentrations in the studied grass cultivars were evaluated. The dry weights of the grasses decreased significantly as the salinity level of the irrigation water increased. At a salinity of 4000 ppm, the Aries perennial ryegrass had the highest dry weight at both sample cuttings. The Aries, Fawn, and Quartet grasses had the highest STI values. The percent of K+ and the K/Na ratio increased as the salinity of the irrigation water increased for the Fawn tall fescue and Quartet perennial ryegrass. In the previously cultivars, the percentage of Na+ decreased as the salinity level of the irrigation water increased, which was in contrast with the results observed for the Tekapo orchardgrass.

Native vegetation in reclamation: Improving habitat and ecosystem function through using prairie species in mine land reclamation

In the Appalachian region, coal mining has impacted 600,000ha historically. While a return to forest would be a preferable postmining land use, due to the difficulty and higher costs of reforestation, many sites are reclaimed into non-native grasslands. The typical seed mix for these grasslands is low diversity and consists of exotic, cool season grasses and forbs. For this study, we combined several species in standard reclamation mixes with prairie species native to North America to create a higher diversity planting on three mine sites in southeastern Ohio. Vegetation and soil microbial properties were assessed within two years after site establishment. Results were encouraging. The mix that included native plants met reclamation standards of ground cover two years after planting, indicating these alternative mixes can be successful. The first year species richness and diversity were higher in native planted areas when compared with traditional, the second year they were equal between treatments. Soil beta-glucosidase activities tended to be lower or higher in the native planted areas, in contrast to soil organic matter, which was generally higher under native prairie mix. Microbial biomass, Actinobacteria, and gram negative bacteria estimated by ester-linked Fatty acid methyl esters occasionally appeared to be higher under native prairie mix indicating that the experimental mix may have a positive effect on soil microbial biomass after almost two years of establishment. Incorporating hardy native prairie plants into reclamation seed mixes can increase the value of the ecosystem for pollinators and wildlife, and potentially improve soil conditions more quickly than non-native plantings alone.

Isolating type-specific phenologies through spectral unmixing of satellite time series

ABSTRACTVegetation phenology is commonly studied using time series of multi-spectral vegetation indices derived from satellite imagery. Differences in reflectance among land-cover and/or plant functional types are obscured by sub-pixel mixing, and so phenological analyses have typically sought to maximize the compositional purity of input satellite data by increasing spatial resolution. We present an alternative method to mitigate this ‘mixed-pixel problem’ and extract the phenological behavior of individual land-cover types inferentially, by inverting the linear mixture model traditionally used for sub-pixel land-cover mapping. Parameterized using genetic algorithms, the method takes advantage of the discriminating capacity of calibrated surface reflectance measurements in red, near infrared, and short-wave infrared wavelengths, as well as the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Water Index. In simulation, the unmixing procedure reproduced the reflectances and phenological signals of grass, crop, and deciduous forests with high fidelity (RMSE < 0.007 NDVI); and in empirical tests, the algorithm extracted the phenological characteristics of evergreen trees and seasonal grasses in a semi-arid savannah. The approach shows potential for a wide range of ecological applications, including detection of differential responses to climate, soil, or other factors among vegetation types.

Allergen-specific immunotherapy modulates the balance of circulating Tfh and Tfr cells

Abstract Follicular helper T cells (Tfh cells) are a CD4 T cell subset essential for germinal center formation and B cell responses, although their role in allergy and allergen-specific immunotherapy (AIT) is unclear. Here, we show that AIT-treated patients have a higher ratio of regulatory Tfh cells (Tfr) to follicular T cells (Tfh) and hypothesize an IL-2 dependent mechanism.

Manure nitrogen characteristics from horses fed warm season grass hays

Manure nitrogen characteristics from horses fed warm season grass hays

Modeling net energy balance of ethanol production from native warm season grasses

There has been an increasing interest in the use of perennial grasses as potential feedstock for ethanol production. The characteristics which make perennial grasses attractive for bioenergy feedstock development initiative are their high yield potential and the high contents of lignin and cellulose. The objective of the study is to model energy input and output and simulate Net Energy Value (NEV) of producing ethanol from native warm season grasses. According to simulated results, the mean NEV of ethanol production from native warm season grasses considered in the analysis was positive. Mean NEV for switchgrass and eastern gammagrass was higher compared to Indiangrass and big bluestem. Although the probability of having positive NEV is high, there is a risk of having negative energy balance under low output scenarios.

Assessment of soil degradation through soil aggregation and particulate organic matter following conversion of riparian buffer to continuous cultivation

SummaryAgriculture in the temperate zone of the Midwestern USA has removed most riparian buffer zones from the landscape, which impairs the soil functioning of the soil in these ecosystems. The objective of this study was to assess soil degradation in a non‐buffered riparian zone with an annual row crop (ARC) and in a longer established (more than 85 years) riparian cool season grass (CSG) buffer in central Iowa, USA. To achieve our objective, we compared the functioning of the target system, ARC, with a system that has been undisturbed since 1990, CSG. We measured the aggregate size distribution and stability of macroaggregrates, aggregate‐associated soil organic carbon and particulate organic matter (POM). The categorization of aggregates by size and water stability (slaking resistance) showed a significantly larger (P &lt; 0.05) proportion of water‐stable macroaggregates (&gt; 250 µm) under CSG (53%) than under ARC (26.3%). On the other hand, soil under ARC had the larger proportion of large and small water‐unstable macroaggregates. The results indicate that the concentration of organic C associated with the total water‐stable aggregates is 1.9 times greater under CSG (23.9 mg C g−1) than for the ARC (12.4 mg C g−1). The concentration of carbon in light particulate organic matter (LPOM‐C) under CSG accounted for 12% of total soil organic carbon (TSOC), but only 6% under ARC management. The chemical composition of LPOM in the ARC soil had a large alkyl‐C/O‐alkyl C ratio, which suggests more organic matter decomposition than with the CSG. Electronic micrographs showed evidence that under CSG roots and fungal hyphae form an extensive network around the large macroaggregates (&gt; 2000 µm), and thus maintain the stability of the macroaggregates. Preserving the CSG buffer reduces soil erosion and the processes associated with nonpoint source pollutants, which improves water quality in an intensively managed agricultural system.Highlights How do soil aggregation and POM change after conversion of CSG buffer to continuous cultivation? Improved understanding of soil degradation through water‐stable and ‐unstable aggregates and SOC. Lack of disturbance of CSG buffer favours formation of macroaggregates and SOC stabilization. Preserving CSG buffer improves water quality in an intensively managed agricultural system.

O-304 Potentiality of four cool season grasses and Miscanthus sinensis for feedstock in the cool region

O-304 Potentiality of four cool season grasses and Miscanthus sinensis for feedstock in the cool region

Effects of crop type and harvest on nest survival and productivity of dickcissels in semi-natural grasslands

Recent focus on climate change and global energy production has increased interest in developing biofuels including perennial native grasses (e.g. switchgrass [Panicum virgatum]) as viable energy commodities while simultaneously maintaining ecosystem function and biodiversity. However, there is limited research examining the effects of biofuel-focused grasslands on grassland bird reproductive success and conservation. In 2011–2013 we studied the effects of vegetation composition and harvest regimens of switchgrass monocultures and native warm-season grass (NWSG) mixtures on nest success, nest density, and productivity for dickcissels (Spiza americana) in Clay Co. MS, USA. There was no effect of vegetation metrics, harvest frequency, or biofuel treatment on nest survival. However, both vegetation composition and harvest frequencies influenced nest density and productivity. Native warm season grasses contained 54–64 times more nests relative to switchgrass treatments, and nest density and productivity were 10% greater in single harvest plots. Our results suggest semi-natural grasslands can balance biofuel production, ecosystem functionality, and conservation so that biofuels offer an opportunity for wildlife conservation rather than a continued threat to grassland birds.

A Review of Perennial Ryegrass Endophytes and Their Potential Use in the Management of African Black Beetle in Perennial Grazing Systems in Australia.

The major insect pest of Australian cool temperate pastures is the root-feeding insect Heteronychus arator (African black beetle, ABB). Significant pasture damage can occur even at low ABB densities (11 individuals per square meter), and often re-sowing of the whole paddock is required. Mitigation of the effects of pasture pests, and in particular subterranean species such as the larval form of ABB, can be challenging. Early detection is limited by the ability to visualize above-ground symptoms, and chemical control of insects in soil is often ineffective. This review takes a look at the historical events that molded the pastoral landscape in Australia. The importation route, changes in land management and pasture composition by European settlers may have aided the establishment of ABB in Australia. Perennial ryegrass Lolium perenne is discussed as it is one of the most important perennial agricultural grasses and is widely-sown in moderate-to-high-rainfall temperate zones of the world. Endophytic fungi from the genus Epichloë form symbiotic relationships with cool season grasses such as Lolium perenne (perennial ryegrass). They have been studied extensively and are well documented for enhancing persistence in pasture via a suite of bioactive secondary metabolites produced by the fungal symbionts. Several well-characterized secondary metabolites are discussed. Some can have negative effects on cattle (e.g., ergovaline and lolitrems) while others have been shown to benefit the host plant through deterrence of insect pests from feeding and by insecticidal activity (e.g., peramine, lolines, ergopeptines). Various control methods for ABB are also discussed, with a focus on the potential role of asexual Epichloë endophytes.

Proso Millet (Panicum miliaceum L.) and Its Potential for Cultivation in the Pacific Northwest, U.S.: A Review.

Proso millet (Panicum miliaceum L.) is a warm season grass with a growing season of 60–100 days. It is a highly nutritious cereal grain used for human consumption, bird seed, and/or ethanol production. Unique characteristics, such as drought and heat tolerance, make proso millet a promising alternative cash crop for the Pacific Northwest (PNW) region of the United States. Development of proso millet varieties adapted to dryland farming regions of the PNW could give growers a much-needed option for diversifying their predominantly wheat-based cropping systems. In this review, the agronomic characteristics of proso millet are discussed, with emphasis on growth habits and environmental requirements, place in prevailing crop rotations in the PNW, and nutritional and health benefits. The genetics of proso millet and the genomic resources available for breeding adapted varieties are also discussed. Last, challenges and opportunities of proso millet cultivation in the PNW are explored, including the potential for entering novel and regional markets.