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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Nitrogen remobilization and conservation, and underlying senescence-associated gene expression in the perennial switchgrass Panicum virgatum

Improving nitrogen (N) remobilization from aboveground to underground organs during yearly shoot senescence is an important goal for sustainable production of switchgrass (Panicum virgatum) as a biofuel crop. Little is known about the genetic control of senescence and N use efficiency in perennial grasses such as switchgrass, which limits our ability to improve the process. Switchgrass aboveground organs (leaves, stems and inflorescences) and underground organs (crowns and roots) were harvested every month over a 3-yr period. Transcriptome analysis was performed to identify genes differentially expressed in various organs during development. Total N content in aboveground organs increased from spring until the end of summer, then decreased concomitant with senescence, while N content in underground organs exhibited an increase roughly matching the decrease in shoot N during fall. Hundreds of senescence-associated genes were identified in leaves and stems. Functional grouping indicated that regulation of transcription and protein degradation play important roles in shoot senescence. Co-expression networks predict important roles for five switchgrass NAC (NAM, ATAF1,2, CUC2) transcription factors (TFs) and other TF family members in orchestrating metabolism of carbohydrates, N and lipids, protein modification/degradation, and transport processes during senescence. This study establishes a molecular basis for understanding and enhancing N remobilization and conservation in switchgrass.

09 BIOMASS FUELS↗
DOE OSTI2021

Iron incorporation both intra- and extra-cellularly improves the yield and saccharification of switchgrass (Panicum virgatum L.) biomass

Abstract Background Pretreatments are commonly used to facilitate the deconstruction of lignocellulosic biomass to its component sugars and aromatics. Previously, we showed that iron ions can be used as co-catalysts to reduce the severity of dilute acid pretreatment of biomass. Transgenic iron-accumulating Arabidopsis and rice plants exhibited higher iron content in grains, increased biomass yield, and importantly, enhanced sugar release from the biomass. Results In this study, we used intracellular ferritin (FerIN) alone and in combination with an improved version of cell wall-bound carbohydrate-binding module fused iron-binding peptide (IBPex) specifically targeting switchgrass, a bioenergy crop species. The FerIN switchgrass improved by 15% in height and 65% in yield, whereas the FerIN/IBPex transgenics showed enhancement up to 30% in height and 115% in yield. The FerIN and FerIN/IBPex switchgrass had 27% and 51% higher in planta iron accumulation than the empty vector (EV) control, respectively, under normal growth conditions. Improved pretreatability was observed in FerIN switchgrass (~ 14% more glucose release than the EV), and the FerIN/IBPex plants showed further enhancement in glucose release up to 24%. Conclusions We conclude that this iron-accumulating strategy can be transferred from model plants and applied to bioenergy crops, such as switchgrass. The intra- and extra-cellular iron incorporation approach improves biomass pretreatability and digestibility, providing upgraded feedstocks for the production of biofuels and bioproducts.

09 BIOMASS FUELS↗
DOE OSTI2016

Deciphering Natural Allelic Variation in Switchgrass for Biomass Yield and Quality Using a Nested Association Mapping Population

Switchgrass (Panicum virgatum L.) is a C4 grass with high biomass yield potential and a model species for bioenergy feedstock development. Understanding the genetic basis of quantitative traits is essential to facilitate genome-enabled breeding programs. The nested association mapping (NAM) analysis combines the best features of both bi-parental and association analyses and can provide high power and high resolution in QTL detection and will ensure significant improvements in biomass yield and quality. To develop a NAM population of switchgrass, 15 highly diverse genotypes with specific characteristics were selected from a diversity panel and crossed to a recurrent parent, AP13, a genotype selected for whole genome sequencing and parent of a mapping population. Ten genotypes from each of the 15 F1 families were then chain crossed. Progenies form each family were randomly selected to develop the NAM population. The switchgrass NAM population consists of a total of 2000 genotypes from 15 families. All the progenies, founder parents, F1 parents (n=2350) were evaluated in replicated field trials at Ardmore, OK and Knoxville, TN. Phenotypic data on plant height, tillering ability, regrowth, flowering time, and biomass yield were collected. Dried biomass samples were also analyzed using prediction equations of NIRS at the Noble Foundation and for lignin content, S/G ratio, and sugar release characteristics at the NREL. Genomic shotgun sequencing of 15 switchgrass NAM founder parental genomes at JGI produced 28-66 Gb high-quality sequence data. Alignment of these sequences with the reference genome, AP13 (v3.0), revealed that up to 99% of the genomic sequences mapped to the reference genome. A total of 2,149 individuals from NAM populations were sequenced by exome capture and two sets of 15 SNP matrices (one for each family) were generated. QTL associated with important traits have been identified and verified in breeding populations. The QTL detected and their associated markers can be used in molecular breeding programs to facilitate development of improved switchgrass cultivars for biofuel production.

09 BIOMASS FUELS↗
DOE OSTI2013

Towards uncovering the roles of switchgrass peroxidases in plant processes

Herbaceous perennial plants selected as potential biofuel feedstocks had been understudied at the genomic and functional genomic levels. Recent investments, primarily by the U.S. Department of Energy, have led to the development of a number of molecular resources for bioenergy grasses, such as the partially annotated genome for switchgrass (Panicum virgatum L.), and some related diploid species. In its current version, the switchgrass genome contains 65,878 gene models arising from the A and B genomes of this tetraploid grass. The availability of these gene sequences provides a framework to exploit transcriptomic data obtained from next-generation sequencing platforms to address questions of biological importance. One such question pertains to discovery of genes and proteins important for biotic and abiotic stress responses, and how these components might affect biomass quality and stress response in plants engineered for a specific end purpose. It can be expected that production of switchgrass on marginal lands will expose plants to diverse stresses, including herbivory by insects. Class III plant peroxidases have been implicated in many developmental responses such as lignification and in the adaptive responses of plants to insect feeding. Here, we have analyzed the class III peroxidases encoded by the switchgrass genome, and have mined available transcriptomic datasets to develop a first understanding of the expression profiles of the class III peroxidases in different plant tissues. Lastly, we have identified switchgrass peroxidases that appear to be orthologs of enzymes shown to play key roles in lignification and plant defense responses to hemipterans.

09 BIOMASS FUELS↗
DOE OSTI2021

Sustainability Trait Modeling of Field-Grown Switchgrass ( Panicum virgatum ) Using UAV-Based Imagery

Unmanned aerial vehicles (UAVs) provide an intermediate scale of spatial and spectral data collection that yields increased accuracy and consistency in data collection for morphological and physiological traits than satellites and expanded flexibility and high-throughput compared to ground-based data collection. In this study, we used UAV-based remote sensing for automated phenotyping of field-grown switchgrass (Panicum virgatum), a leading bioenergy feedstock. Using vegetation indices calculated from a UAV-based multispectral camera, statistical models were developed for rust disease caused by Puccinia novopanici, leaf chlorophyll, nitrogen, and lignin contents. For the first time, UAV remote sensing technology was used to explore the potentials for multiple traits associated with sustainable production of switchgrass, and one statistical model was developed for each individual trait based on the statistical correlation between vegetation indices and the corresponding trait. Also, for the first time, lignin content was estimated in switchgrass shoots via UAV-based multispectral image analysis and statistical analysis. The UAV-based models were verified by ground-truthing via correlation analysis between the traits measured manually on the ground-based with UAV-based data. The normalized difference red edge (NDRE) vegetation index outperformed the normalized difference vegetation index (NDVI) for rust disease and nitrogen content, while NDVI performed better than NDRE for chlorophyll and lignin content. Overall, linear models were sufficient for rust disease and chlorophyll analysis, but for nitrogen and lignin contents, nonlinear models achieved better results. As the first comprehensive study to model switchgrass sustainability traits from UAV-based remote sensing, these results suggest that this methodology can be utilized for switchgrass high-throughput phenotyping in the field.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Physical insight into switchgrass dissolution in the ionic liquid 1-ethyl-3-methylimidazolium acetate

Small-angle neutron scattering was used to characterize solutions of switchgrass and the constituent biopolymers cellulose, hemicellulose, and lignin, as well as a physical mixture of them mimicking the composition of switchgrass, dissolved in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate. The results demonstrate that the IL dissolves the cellulose fibrils of switchgrass, although a supramolecular biopolymer network remains that is not present in solutions of the individual biopolymers and that does not self-assemble in a solution containing the physical mixture of the individual biopolymers. The persistence of a network-like structure indicates that dissolving switchgrass in the IL does not disrupt all of the physical entanglements and covalent linkages between the biopolymers created during plant growth. Reconstitution of the IL-dissolved switchgrass yields carbohydrate-rich material containing cellulose with a low degree of crystallinity, as determined by powder X-ray diffraction, which impacts potential down-stream uses of the biopolymers produced by the process. The data suggests that the use of chemical additives which would break bonds that exist between the lignin and hemicellulose might improve the purity of the resulting product, but may not be able to disrupt the highly physically-entangled biopolymer network sufficiently to facilitate their separation.

Wang, Hui↗
DOE OSTI2021

Serendipita Fungi Modulate the Switchgrass Root Transcriptome to Circumvent Host Defenses and Establish a Symbiotic Relationship

The fungal family Serendipitaceae encompasses root-associated lineages with endophytic, ericoid, orchid, and ectomycorrhizal lifestyles. Switchgrass is an important bioenergy crop for cellulosic ethanol production owing to high biomass production on marginal soils otherwise unfit for food crop cultivation. The aim of this study was to investigate the host plant responses to Serendipita spp. colonization by characterizing the switchgrass root transcriptome during different stages of symbiosis in vitro. For this, we included a native switchgrass strain, Serendipita bescii, and a related strain, S. vermifera, isolated from Australian orchids. Serendipita colonization progresses from thin hyphae that grow between root cells to, finally, the production of large, bulbous hyphae that fill root cells during the later stages of colonization. We report that switchgrass seems to perceive both fungi prior to physical contact, leading to the activation of chemical and structural defense responses and putative host disease resistance genes. Subsequently, the host defense system appears to be quenched and carbohydrate metabolism adjusted, potentially to accommodate the fungal symbiont. In addition, prior to contact, switchgrass exhibited significant increases in root hair density and root surface area. Furthermore, genes involved in phytohormone metabolism such as gibberellin, jasmonic acid, and salicylic acid were activated during different stages of colonization. Both fungal strains induced plant gene expression in a similar manner, indicating a conserved plant response to members of this fungal order. Understanding plant responsiveness to Serendipita spp. will inform our efforts to integrate them into forages and row crops for optimal plant–microbe functioning, thus facilitating low-input, sustainable agricultural practices.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Switchgrass nitrogen response and estimated production costs on diverse sites

Switchgrass ( Panicum virgatum L.) has been the principal perennial herbaceous crop investigated for bioenergy production in North America given its high production potential, relatively low input requirements, and potential suitability for use on marginal lands. Few large trials have determined switchgrass yields at field scale on marginal lands, including analysis of production costs. Thus, a field–scale study was conducted to develop realistic yield and cost estimates for diverse regions of the USA. Objectives included measuring switchgrass response to fertility treatments (0, 56, and 112 kg N ha –1 ) and generating corresponding estimates of production costs for sites with diverse soil and climatic conditions. Trials occurred in Iowa, New York, Oklahoma, South Dakota, and Virginia, USA. Cultivars and management practices were site specific, and field–scale equipment was used for all management practices. Input costs were estimated using final harvest–year (2015) prices, and equipment operation costs were estimated with the MachData model (2015). Switchgrass yields generally were below those reported elsewhere, averaging 6.3 Mg ha –1 across sites and treatments. Establishment stand percent ranged from 28% to 76% and was linked to initial year production. No response to N was observed at any site in the first production year. In subsequent seasons, N generally increased yields on well–drained soils; however, responses to N were nil or negative on less well–drained soils. Greatest percent increases in response to 112 kg N ha –1 were 57% and 76% on well–drained South Dakota and Virginia sites, where breakeven prices to justify N applications were over 70 and 63 Mg –1 , respectively. For some sites, typically promoted N application rates may be economically unjustified; it remains unknown whether a bioenergy industry can support the breakeven prices estimated for sites where N inputs had positive effects on switchgrass yield.

09 BIOMASS FUELS↗
DOE OSTI2023

A 30% reduction in switchgrass rhizome reserves did not decrease biomass yield

Abstract A long‐standing question in perennial grass breeding and physiology is whether yield improvement strategies could compromise winter survival. Since perennial grasses rely on stored carbohydrates for winter maintenance and spring regrowth, yield improvement strategies could reduce winter survival if they increase biomass and grain yields at the expense of carbon allocation to storage. Therefore, it is crucial to comprehend the dependence of regrowth on storage reserves. We experimentally depleted switchgrass ( Panicum virgatum L.) rhizome reserves by storing rhizomes for 2 weeks at 5°C (control treatment) and 25°C (reserve‐depleted treatment). During the storage period rhizome respiration was 5.3× higher at 25°C (0.010 μmol CO 2 g −1 min −1 at 5°C vs. 0.054 μmol CO 2 g −1 min −1 at 25°C; p < 0.0001) and the starch content was depleted by 30% by the end of storage. Surprisingly, reserve‐depleted switchgrass had 60% larger leaf area (LA; LA control = 149 cm 2 pot −1 vs. LA depleted = 239 cm 2 pot −1 ; p = 0.013) and produced ~40% more aboveground biomass than control plants (9.46 g pot −1 vs. 6.63 g pot −1 ; p = 0.112). In addition, reserve‐depleted switchgrass restored its rhizome starch reserves to pre‐storage levels. Switchgrass showed a large plasticity among its source‐sink components to buffer the imposed reserve depletion. It increased plant photosynthesis by increasing the photosynthetic leaf area while keeping photosynthesis constant on a leaf area basis and readjusted the timing and activity of sink organs. These results suggest that switchgrass, and potentially other perennial grasses, largely over‐invest in storage reserves. Therefore, current breeding strategies in perennial grasses aimed to extend the aboveground growing season should not compromise crop persistence. Our study also has implications on long‐term yield dynamics as it highlights sink limitations as potential driver of the yield decline commonly observed in perennial grasses 5+ years after cultivation.

Tejera‐Nieves, Mauricio↗
DOE OSTI2024

High temperatures and low soil moisture synergistically reduce switchgrass yields from marginal field sites and inhibit fermentation

‘Marginal lands’ are low productivity sites abandoned from agriculture for reasons such as low or high soil water content, challenging topography, or nutrient deficiency. To avoid competition with crop production, cellulosic bioenergy crops have been proposed for cultivation on marginal lands, however on these sites they may be more strongly affected by environmental stresses such as low soil water content. In this study we used rainout shelters to induce low soil moisture on marginal lands and determine the effect of soil water stress on switchgrass growth and the subsequent production of bioethanol. Five marginal land sites that span a latitudinal gradient in Michigan and Wisconsin were planted to switchgrass in 2013 and during the 2018–2021 growing seasons were exposed to reduced precipitation under rainout shelters in comparison to ambient precipitation. The effect of reduced precipitation was related to the environmental conditions at each site and biofuel production metrics (switchgrass biomass yields and composition and ethanol production). During the first year (2018), the rainout shelters were designed with 60% rain exclusion, which did not affect biomass yields compared to ambient conditions at any of the field sites, but decreased switchgrass fermentability at the Wisconsin Central–Hancock site. In subsequent years, the shelters were redesigned to fully exclude rainfall, which led to reduced biomass yields and inhibited fermentation for three sites. When switchgrass was grown in soils with large reductions in moisture and increases in temperature, the potential for biofuel production was significantly reduced, exposing some of the challenges associated with producing biofuels from lignocellulosic biomass grown under drought conditions.

09 BIOMASS FUELS↗
DOE OSTI2025

Switchgrass Steroidal Saponins Reduce Fungal Disease but Decrease Yeast Fermentation Yield

Increasing the production of bioproducts from lignocellulosic feedstocks requires improvement in both field production and biorefinery efficiency. When plant traits arise that improve field production but decrease biofuel yield, these trade-offs can represent challenges in the entire production process. To examine trade-offs between field and production traits, we examined factors underlying switchgrass resistance to fungal rust pathogens in field conditions and factors that impede yeast fermentation in the lab using repeated measurements on a switchgrass genetic diversity panel. We found that the same switchgrass genotypes that showed high fungal pathogen resistance also showed recalcitrance to yeast fermentation. These switchgrass genotypes were mostly from the Atlantic genetic group, which had high levels of specialized metabolites of the saponin class. Among 1589 metabolites identified through metabolomics, we found that saponins were among the most likely to explain variation in both rust infection and fermentation yield using random forest feature selection, and that only four of these were sufficient to explain 57.9% of the variation in rust susceptibility. Through follow-up testing in recalcitrant biomass, we found that the bacterium Zymomonas mobilis does not suffer the same inhibition as the yeast Saccharomyces cerevisiae, and that the addition of ergosterol (thought to be the fungal cellular target of saponin inhibition) rescues yeast fermentation. Several lines of evidence point to a central role for saponins as key metabolites protecting switchgrass from fungal pathogens and interfering with yeast fermentation, underscoring an ongoing need for collaboration between plant breeders and biofuel production scientists.

VanWallendael, Acer [North Carolina State Universi↗
DOE OSTI2019

Embryogenic cell suspensions for high-capacity genetic transformation and regeneration of switchgrass (Panicum virgatum L.)

Abstract Background Switchgrass ( Panicum virgatum L.), a North American prairie grassland species, is a potential lignocellulosic biofuel feedstock owing to its wide adaptability and biomass production. Production and genetic manipulation of switchgrass should be useful to improve its biomass composition and production for bioenergy applications. The goal of this project was to develop a high-throughput stable switchgrass transformation method using Agrobacterium tumefaciens with subsequent plant regeneration. Results Regenerable embryogenic cell suspension cultures were established from friable type II callus-derived inflorescences using two genotypes selected from the synthetic switchgrass variety ‘Performer’ tissue culture lines 32 and 605. The cell suspension cultures were composed of a heterogeneous fine mixture culture of single cells and aggregates. Agrobacterium tumefaciens strain GV3101 was optimum to transfer into cells the pANIC-10A vector with a hygromycin-selectable marker gene and a pporRFP orange fluorescent protein marker gene at an 85% transformation efficiency. Liquid cultures gave rise to embryogenic callus and then shoots, of which up to 94% formed roots. The resulting transgenic plants were phenotypically indistinguishable from the non-transgenic parent lines. Conclusion The new cell suspension-based protocol enables high-throughput Agrobacterium -mediated transformation and regeneration of switchgrass in which plants are recovered within 6–7 months from culture establishment.

Ondzighi-Assoume, Christine A.↗
DOE OSTI2015

Physiological Evaluation of Alkali-Salt Tolerance of Thirty Switchgrass ( Panicum virgatum ) Lines

Soil salt-alkalization is a major limiting factor for crop production in many regions. Switchgrass (Panicum virgatum L.) is a warm-season C 4 perennial rhizomatous bunchgrass and a target lignocellulosic biofuel species. The objective of this study was to evaluate relative alkali-salt tolerance among 30 switchgrass lines. Tillers of each switchgrass line were transplanted into pots filled with fine sand. Two months after transplanting, plants at E5 developmental stage were grown in either half strength Hoagland’s nutrient solution with 0 mM Na + (control) or half strength Hoagland’s nutrient solution with 150 mM Na + and pH of 9.5 (alkalisalt stress treatment) for 20 d. Alkali-salt stress damaged cell membranes [higher electrolyte leakage (EL) ], reduced leaf relative water content (RWC), net photosynthetic rate (Pn), stomatal conductance (g s ), and transpiration rate (Tr). An alkali-salt stress tolerance trait index (ASTTI) for each parameter was calculated based on the ratio of the value under alkali-salt stress and the value under non-stress conditions for each parameter of each line. Relative alkali-salt tolerance was determined based on principal components analysis and cluster analysis of the physiological parameters and their ASTTI values. Significant differences in alkali-salt stress tolerance were found among the 30 lines. Lowland lines TEMSEC, Alamo, TEM-SLC and Kanlow were classified as alkali-salt tolerant. In contrast, three lowland lines (AM-314/MS-155, BN-13645-64) and two upland lines (Caddo and Blackwell1) were classified as alkali-salt sensitive. The results suggest wide variations exist in alkalisalt stress tolerance among the 30 switchgrass lines. The approach of using a combination of principal components and cluster analysis of the physiological parameters and related ASTTI is feasible for evaluating alkali-salt tolerance in switchgrass.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Functional Characterization of NAC and MYB Transcription Factors Involved in Regulation of Biomass Production in Switchgrass ( Panicum virgatum )

Switchgrass is a promising biofuel feedstock due to its high biomass production and low agronomic input requirements. Because the bulk of switchgrass biomass used for biofuel production is lignocellulosic secondary walls, studies on secondary wall biosynthesis and its transcriptional regulation are imperative for designing strategies for genetic improvement of biomass production in switchgrass. Here, we report the identification and functional characterization of a group of switchgrass transcription factors, including several NACs (PvSWNs) and a MYB (PvMYB46A), for their involvement in regulating secondary wall biosynthesis. PvSWNs and PvMYB46A were found to be highly expressed in stems and their expression was closely associated with sclerenchyma cells. Overexpression of PvSWNs and PvMYB46A in Arabidopsis was shown to result in activation of the biosynthetic genes for cellulose, xylan and lignin and ectopic deposition of secondary walls in normally parenchymatous cells. Transactivation and complementation studies demonstrated that PvSWNs were able to activate the SNBE-driven GUS reporter gene and effectively rescue the secondary wall defects in the Arabidopsis snd1 nst1 double mutant, indicating that they are functional orthologs of Arabidopsis SWNs. Furthermore, we showed that PvMYB46A could activate the SMRE-driven GUS reporter gene and complement the Arabidopsis myb46 myb83 double mutant, suggesting that it is a functional ortholog of Arabidopsis MYB46/MYB83. Together, these results indicate that PvSWNs and PvMYB46A are transcriptional switches involved in regulating secondary wall biosynthesis, which provides molecular tools for genetic manipulation of biomass production in switchgrass.

09 BIOMASS FUELS↗
DOE OSTI2018

Antioxidant metabolism variation associated with alkali-salt tolerance in thirty switchgrass (Panicum virgatum) lines

Soil salinization is a major factor limiting crop growth and development in many areas. Switchgrass (Panicum virgatum L.) is an important warm-season grass species used for biofuel production. The objective of this study was to investigate antioxidant metabolism, proline,and protein variation associated with alkali-salt tolerance among 30 switchgrass lines and identify metabolic markers for evaluating alkali-salt tolerance of switchgrass lines. The grass lines were transplanted into plastic pots containing fine sand. When the plants reached E5 developmental stage, they were subjected to either alkali-salt stress treatment (150 mM Na + and pH of 9.5) or control (no alkali-salt stress) for 20 d. The 30 switchgrass lines differed in alkali-salt tolerance as determined by the level of leaf malondialdehyde (MDA), antioxidant enzyme activity [(superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX)], proline and protein. Alkali-salt stress increased MDA, proline, SOD, reduced CAT activity, but its effect on protein and APX varied depending on lines. Wide variations in the five parameters existed among the 30 lines. In general, the lines with higher CAT activity and lower proline content under alkali-salt stress had less MDA, exhibiting better alkali-salt tolerance. Among the five parameters, CAT can be considered as valuable metabolic markers for assessment of switchgrass tolerance to alkali-salt stress.

09 BIOMASS FUELS↗
DOE OSTI2016

AmeriFlux US-AR1 ARM USDA UNL OSU Woodward Switchgrass 1

This is the AmeriFlux version of the carbon flux data for the site US-AR1 ARM USDA UNL OSU Woodward Switchgrass 1. Site Description - The ARM USDA UNL OSU Woodward Switchgrass 1 tower is located on public land owned by the USDA-ARS Southern Plains Range Research Station in Woodward, Oklahoma. The site is on a former native prairie that is in the process of changing to switchgrass. A second companion site (ARM USDA UNL OSU Woodward Switchgrass 2) is on a former wheat field. In Spring 2009, the former native prairie site was burned, cattle were put on the pasture to graze down emergent grass, and broadleaf herbicide was sprayed. In Summer 2009, the cattle were removed from the pasture, and the site was sprayed with herbicide to kill all grass. In Spring 2010, prior to the planting of switchgrass, final herbicide was sprayed to kill cheat grass and to control broadleaf plants.

Billesbach, Dave↗
DOE OSTI2016

AmeriFlux US-AR2 ARM USDA UNL OSU Woodward Switchgrass 2

This is the AmeriFlux version of the carbon flux data for the site US-AR2 ARM USDA UNL OSU Woodward Switchgrass 2. Site Description - The ARM USDA UNL OSU Woodward Switchgrass 2 tower is located on public land owned by the USDA-ARS Southern Plains Range Research Station in Woodward, Oklahoma. The site is on a former wheat field that is in the process of changing to switchgrass. A companion site (ARM USDA UNL OSU Woodward Switchgrass 1) is on a former native prairie. Previous wheat was planted in Fall 2008. In Spring 2009, herbicide was applied to kill the wheat prior to switchgrass planting. Later in the year, the site was sprayed with post-emergence herbicide. In 2010, fertilization occurred before herbicide was sprayed for broadleaf control.

Billesbach, Dave↗
DOE OSTI2017

Switchgrass Biomass Quality as Affected by Nitrogen Rate, Harvest Time, and Storage

The purpose of this study was to assess the changes in switchgrass (Panicum virgatum L.) biomass quality as affected by N rate, harvest time, and storage. This research was conducted near Bristol, SD, in 2010 and 2011. Treatments included three N rates (0, 56, and 112 kg N ha –1 ) applied annually and each N rate replicated four times. After a killing frost, all of the plots were harvested and baled in large round bales in October 2010 and November 2011. An area of about 30 m 2 from each plot was left unharvested to represent storage of standing switchgrass over the winter and to determine dry matter yields. Switchgrass was analyzed for hemicellulose, cellulose, lignin, mineral elements, N, and C. In the first season, storage of the fall harvested switchgrass bales numerically increased the concentrations of hemicellulose, lignin, and N. In the second season, they increased significantly. Mineral elements significantly increased in both sampling seasons. Delaying harvest until spring decreased lignin, N, and mineral elements concentration, and increased cellulose and hemicellulose concentrations, but also reduced biomass yield. Results from this study suggest that delaying the switchgrass harvest until spring increased the overall feedstock quality for ethanol production, but yield reductions must be considered to determine the overall economic impact of a delayed harvest.

54 ENVIRONMENTAL SCIENCES↗