The Experts below are selected from a list of 13095 Experts worldwide ranked by ideXlab platform
Michael D. Casler - One of the best experts on this subject based on the ideXlab platform.
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Switchgrass genomic diversity ploidy and evolution novel insights from a network based snp discovery protocol
PLOS Genetics, 2013Co-Authors: Fei Lu, Michael D. Casler, Alexander E Lipka, Jeff Glaubitz, Robert J Elshire, Jerome H Cherney, Edward S BucklerAbstract:Switchgrass (Panicum virgatum L.) is a perennial grass that has been designated as an herbaceous model biofuel crop for the United States of America. To facilitate accelerated breeding programs of Switchgrass, we developed both an association panel and linkage populations for genome-wide association study (GWAS) and genomic selection (GS). All of the 840 individuals were then genotyped using genotyping by sequencing (GBS), generating 350 GB of sequence in total. As a highly heterozygous polyploid (tetraploid and octoploid) species lacking a reference genome, Switchgrass is highly intractable with earlier methodologies of single nucleotide polymorphism (SNP) discovery. To access the genetic diversity of species like Switchgrass, we developed a SNP discovery pipeline based on a network approach called the Universal Network-Enabled Analysis Kit (UNEAK). Complexities that hinder single nucleotide polymorphism discovery, such as repeats, paralogs, and sequencing errors, are easily resolved with UNEAK. Here, 1.2 million putative SNPs were discovered in a diverse collection of primarily upland, northern-adapted Switchgrass populations. Further analysis of this data set revealed the fundamentally diploid nature of tetraploid Switchgrass. Taking advantage of the high conservation of genome structure between Switchgrass and foxtail millet (Setaria italica (L.) P. Beauv.), two parent-specific, synteny-based, ultra high-density linkage maps containing a total of 88,217 SNPs were constructed. Also, our results showed clear patterns of isolation-by-distance and isolation-by-ploidy in natural populations of Switchgrass. Phylogenetic analysis supported a general south-to-north migration path of Switchgrass. In addition, this analysis suggested that upland tetraploid arose from upland octoploid. All together, this study provides unparalleled insights into the diversity, genomic complexity, population structure, phylogeny, phylogeography, ploidy, and evolutionary dynamics of Switchgrass.
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The Evolution of Switchgrass as an Energy Crop
Green Energy and Technology, 2012Co-Authors: David J. Parrish, Michael D. Casler, Andrea MontiAbstract:This chapter discusses the prehistoric origins of Switchgrass, its mid-twentieth century adoption as a crop, and late-twentieth century efforts to develop it into an energy crop. The species probably first appeared about 2 million years ago (MYA) and has continued to evolve since, producing two distinct ecotypes and widely varying ploidy levels. We build the case that all existing Switchgrass lineages must be descended from plants that survived the most recent glaciation of North America and then, in just 11,000 years, re-colonized the eastern two-thirds of the continent. Moving to historic times, we discuss how Switchgrass was first considered as a crop to be grown in monoculture only in the 1940s. Based on scientific reports indexed in a well-known database, interest in Switchgrass grew very slowly from the 1940s until it began being considered by the US department of energy (DOE) as a potential energy crop in the 1980s. The history of how Switchgrass became DOE’s ‘model’ herbaceous energy crop species is recounted here. Also chronicled are the early research efforts on Switchgrass-for-energy in the US, Canada, and Europe and the explosive growth in the last decade of publications discussing Switchgrass as an energy crop. If Switchgrass—still very much a ‘wild’ species, especially compared to several domesticated grasses—truly attains global status as a species of choice for bioenergy technologies, it will have been a very remarkable evolution.
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The Switchgrass Genome: Tools and Strategies
The Plant Genome, 2011Co-Authors: Michael D. Casler, Christian M Tobias, Jeremy Schmutz, Shawn M. Kaeppler, C. Robin Buell, Zeng-yu Wang, Peijian Cao, Pamela C. RonaldAbstract:Switchgrass (Panicum virgatum L.) is a perennial grass species receiving signifi cant focus as a potential bioenergy crop. In the last 5 yr the Switchgrass research community has produced a genetic linkage map, an expressed sequence tag (EST) database, a set of single nucleotide polymorphism (SNP) markers that are distributed across the 18 linkage groups, 4x sampling of the P. virgatum AP13 genome in 400-bp reads, and bacterial artifi cial chromosome (BAC) libraries containing over 200,000 clones. These studies have revealed close collinearity of the Switchgrass genome with those of sorghum [Sorghum bicolor (L.) Moench], rice (Oryza sativa L.), and Brachypodium distachyon (L.) P. Beauv. Switchgrass researchers have also developed several microarray technologies for gene expression studies. Switchgrass genomic resources will accelerate the ability of plant breeders to enhance productivity, pest resistance, and nutritional quality. Because Switchgrass is a relative newcomer to the genomics world, many secrets of the Switchgrass genome have yet to be revealed. To continue to effi ciently explore basic and applied topics in Switchgrass, it will be critical to capture and exploit the knowledge of plant geneticists and breeders on the next logical steps in the development and utilization of genomic resources for this species. To this end, the community has established a Switchgrass genomics executive committee and work group (http://Switchgrassgenomics.org/
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hierarchical classification of Switchgrass genotypes using ssr and chloroplast sequences ecotypes ploidies gene pools and cultivars
Theoretical and Applied Genetics, 2011Co-Authors: Juan Zalapa, Christian M Tobias, Shawn M. Kaeppler, David L Price, M Okada, Michael D. CaslerAbstract:Switchgrass (Panicum virgatum L.) is an important crop for bioenergy feedstock development. Switchgrass has two main ecotypes: the lowland ecotype being exclusively tetraploid (2n = 4x = 36) and the upland ecotype being mainly tetraploid and octaploid (2n = 8x = 72). Because there is a significant difference in ploidy, morphology, growth pattern, and zone of adaptation between and within the upland and lowland ecotypes, it is important to discriminate Switchgrass plants belonging to different genetic pools. We used 55 simple sequence repeats (SSR) loci and six chloroplast sequences to identify patterns of variation between and within 18 Switchgrass cultivars representing seven lowland and 11 upland cultivars from different geographic regions and of varying ploidy levels. We report consistent discrimination of Switchgrass cultivars into ecotype membership and demonstrate unambiguous molecular differentiation among Switchgrass ploidy levels using genetic markers. Also, SSR and chloroplast markers identified genetic pools related to the geographic origin of the 18 cultivars with respect to ecotype, ploidy, and geographical, and cultivar sources. SSR loci were highly informative for cultivar fingerprinting and to classify plants of unknown origin. This classification system is the first step toward developing Switchgrass complementary gene pools that can be expected to provide a significant heterotic increase in biomass yield.
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Switchgrass as a biofuels feedstock in the USA
Canadian Journal of Plant Science, 2006Co-Authors: Matt A Sanderson, Michael D. Casler, Paul R. Adler, Akwasi A. Boateng, Gautam SarathAbstract:Switchgrass (Panicum virgatum L.) has been identified as a model herbaceous energy crop for the USA. In this review, we selectively highlight current USDA-ARS research on Switchgrass for biomass energy. Intensive research on Switchgrass as a biomass feedstock in the 1990s greatly improved our understanding of the adaptation of Switchgrass cultivars, production practices, and environmental benefits. Several constraints still remain in terms of economic production of Switchgrass for biomass feedstock including reliable establishment practices to ensure productive stands in the seeding year, efficient use of fertilizers, and more efficient methods to convert lignocellulose to biofuels. Overcoming the biological constraints will require genetic enhancement, molecular biology, and plant breeding efforts to improve Switchgrass cultivars. New genomic resources will aid in developing molecular markers, and should allow for marker-assisted selection of improved germplasm. Research is also needed on profitable mana...
Matt A Sanderson - One of the best experts on this subject based on the ideXlab platform.
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Switchgrass as a biofuels feedstock in the USA
Canadian Journal of Plant Science, 2006Co-Authors: Matt A Sanderson, Michael D. Casler, Paul R. Adler, Akwasi A. Boateng, Gautam SarathAbstract:Switchgrass (Panicum virgatum L.) has been identified as a model herbaceous energy crop for the USA. In this review, we selectively highlight current USDA-ARS research on Switchgrass for biomass energy. Intensive research on Switchgrass as a biomass feedstock in the 1990s greatly improved our understanding of the adaptation of Switchgrass cultivars, production practices, and environmental benefits. Several constraints still remain in terms of economic production of Switchgrass for biomass feedstock including reliable establishment practices to ensure productive stands in the seeding year, efficient use of fertilizers, and more efficient methods to convert lignocellulose to biofuels. Overcoming the biological constraints will require genetic enhancement, molecular biology, and plant breeding efforts to improve Switchgrass cultivars. New genomic resources will aid in developing molecular markers, and should allow for marker-assisted selection of improved germplasm. Research is also needed on profitable mana...
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Nutrient movement and removal in a Switchgrass biomass-filter strip system treated with dairy manure.
Journal of Environmental Quality, 2001Co-Authors: Matt A Sanderson, R L Reed, Ronald M. Jones, Marshall J. Mcfarland, Jason Stroup, James P. MuirAbstract:: Manure use on cropland has raised concern about nutrient contamination of surface and ground waters. Warm-season perennial grasses may be useful in filter strips to trap manure nutrients and as biomass feedstock for nutrient removal. We explored the use of 'Alamo' Switchgrass (Panicum virgatum L.) in a biomass production-filter strip system treated with dairy manure. We measured changes in extractable P in the soil, NO3 -N in soil water, and changes in total reactive P and chemical oxygen demand (COD) of runoff water before and after a Switchgrass filter strip. Five rates of dairy manure (target rates of 0, 50, 100, 150, and 200 kg N ha(-1) from solid manure in 1995; 0, 75, 150, 300, and 600 kg N ha(-1) from lagoon effluent in 1996 and 1997) were surface-applied to field plots of Switchgrass (5.2 by 16.4 m) with a 5.2- by 16.4-m Switchgrass filter strip below the manured area. Yield of Switchgrass from the manured area increased linearly with increasing manure rate in each year. Soil water samples collected at 46 or 91 cm below the soil surface on 30 dates indicated < 3 mg L(-1) of NO3-N in all plots. Concentrations of total reactive P in surface runoff water were reduced an average of 47% for the 150 kg N rate and 76% for the 600 kg N rate in 1996 and 1997 after passing through the strip. Manure could effectively substitute for inorganic fertilizer in Switchgrass biomass production with dual use of the Switchgrass as a vegetative filter strip.
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Switchgrass cultivars and germplasm for biomass feedstock production in texas
Bioresource Technology, 1999Co-Authors: Matt A Sanderson, R L Reed, W R Ocumpaugh, M A Hussey, G A Van Esbroeck, Charles R. Tischler, J C Read, Frank M HonsAbstract:Abstract Switchgrass ( Panicum virgatum L.) is a warm-season perennial grass indigenous to North America with excellent potential as a bioenergy crop. Our objective was to determine the yield potential and adaptability of Switchgrass cultivars and germplasms in diverse Texas environments where the species might be used as a bioenergy crop. We determined the adaptability of several Switchgrass cultivars and germplasms at five ecologically different locations (Beeville, College Station, Dallas, Stephenville, and Temple) in Texas in two experiments during 1992 to 1996. Alamo Switchgrass was the best adapted commercially available Switchgrass cultivar for biomass feedstock production in Texas in these trials with yields of 8 to 20 Mg ha −1 . A single harvest in the fall maximized biomass yield and maintained Switchgrass stands. Although very tolerant of moderate or even severe drought, Switchgrass failed to yield under chronic extreme drought. At Beeville in 1996, there was no harvestable Switchgrass growth because of extreme drought. Upland cultivars from the midwest matured early and did not produce as much biomass as lowland cultivars from the southern U.S. The predominant factor affecting Switchgrass productivity in these Texas locations seemed to be rainfall amount. The highest biomass yield at each location generally occurred in years of greatest April to September rainfall. Soil type did not appear to have much influence on biomass production. Soil organic carbon increased from 11.1 to 15. 8 g kg −1 in the upper 30 cm of soil (average of four locations) during 1992 to 1996. These increases in organic carbon indicate a good potential for sequestering carbon through biomass production.
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Switchgrass as a sustainable bioenergy crop
Bioresource Technology, 1996Co-Authors: Matt A Sanderson, R L Reed, Samuel B. Mclaughlin, Stan D. Wullschleger, B.v. Conger, David J. Parrish, D.d. Wolf, C. Taliaferro, A.a. Hopkins, W R OcumpaughAbstract:Switchgrass (Panicum virgatum L.) shows potential as a sustainable herbaceous energy crop from which a renewable source of transportation fuel and/or biomass-generated electricity could be derived. In 1992, a new research program focused on developing Switchgrass as a biomass energy feedstock was initiated by the U.S. Department of Energy in five of the southern United States. The multifaceted, multi-institution research addresses breeding for improved biomass yields, regional field tests, cultural practices, physiology and tissue culture. Recent progress is highlighted in this paper. Preliminary results from the breeding program indicate that recurrent restricted phenotypic selection could lead to development of new cultivars. A technique for regenerating Switchgrass plants via tissue culture has been proven and new populations of regenerated plants have been established in the field. Performance trials at three regional cultivar testing centers in Virginia, Alabama and Texas have shown that ‘Alamo’ Switchgrass has higher biomass yield and broader adaptability than other cultivars tested. Research on management practices designed to maximize biomass yield has shown that multiple harvests of Switchgrass may reduce total seasonal yields in some instances and that responses to fertilizer inputs vary with the environment. Seed dormancy often retards rapid establishment of competitive stands of Switchgrass. Our research has indicated that seed dormancy can be modified, resulting in increased seed germination and a greater number of Switchgrass plants. Research on the physiology of Switchgrass has shown that lowland and upland ecotypes differ in photosynthetic rate but not in respiration rate. Findings in each of these areas can contribute to development of Switchgrass as a sustainable bioenergy crop. Future research will address molecular biology techniques for exploiting genetic variation, explore canopy architecture and carbon allocation patterns affecting biomass yield, elucidate key factors in successful establishment of Switchgrass and provide technology transfer that facilitates scale-up of Switchgrass production for commercial energy production.
Robert B. Mitchell - One of the best experts on this subject based on the ideXlab platform.
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Understanding Variation in Switchgrass Biomass Composition
2012Co-Authors: Marty R. Schmer, Robert B. Mitchell, K. P. Vogel, Bruce S. Dien, H. G. Jung, M. D. CaslerAbstract:Switchgrass is being developed as a cellulosic ethanol feedstock for the temperate regions of North America. Cellulosic ethanol sources, such as Switchgrass, have the potential to displace a significant portion of current United States petroleum consumption. Cellulosic refineries using biochemical processing will convert biomass cell wall carbohydrates into simple sugars and microorganisms will then ferment the simple sugars into ethanol. A reliable Switchgrass supply will be important to cellulosic refineries to ensure stable operational costs. Switchgrass ethanol production (L ha-1) is influenced by both biomass yield and biomass composition. Switchgrass biomass yield potential data is becoming available but the potential effects of production practices, cultivars, and environment on Switchgrass biomass composition and subsequently on ethanol yields has not been previously determined. To better understand the extent of Switchgrass biomass composition variation, USDA-ARS researchers utilized newly developed near-infrared reflectance spectroscopy (NIRS) calibrations for Switchgrass biomass to estimate biomass composition. With this information, the ethanol yield per ton of Switchgrass biomass can be calculated. Near-infrared reflectance spectroscopy is a non-destructive technology that uses the spectral characteristics of a sample to obtain composition information and has been widely used in the food, forage, and pharmaceutical industries. The Switchgrass biomass NIRS composition calibrations which were developed by a team of USDA-ARS scientists are able to accurately estimate 20 components in Switchgrass biomass including all cell wall and other carbohydrates which determine the amount of ethanol that could be produced in a biorefinery. In the January-February 2011 issue of Agronomy Journal, Switchgrass NIRS prediction equations were used to estimate cell wall composition and theoretical ethanol yields on both a per ton and per hectare basis from 10 Switchgrass fields in a three state region. Ethanol conversion rates differed across locations and over time but ethanol conversion rates (L Mg-1) within a Switchgrass field from a single growing season were relatively stable. Results indicate that the amount of hexose (six-carbon) sugars and pentose (five-carbon) sugars varied over years which impacted ethanol conversion rates. Cell wall glucose was the primary hexose sugar and xylose was the primary pentose sugar. Annual biomass yield and cell wall glucose concentrations were positively correlated across all experimental field locations. According to the authors, it should be feasible to increase ethanol production by improving both biomass yield and conversion efficiency. Proper management and improved Switchgrass cultivars can reduce biomass composition variation but weather conditions will have a strong impact on ethanol yield potential. Results of this study demonstrate the biorefineries can expect significant year-to-year variation in biomass cell wall composition from a given Switchgrass field and across production regions. Cellulosic refineries will need to consider this variation in biofuel yields when implementing their biochemical conversion technology and business plans. Switchgrass bales will need to be sampled prior to conversion to quantify cell wall composition. Results from sampled Switchgrass bales could possibly be used to modify pretreatment and enzyme requirements to optimize ethanol conversion rates. The USDA-ARS Switchgrass NIRS bioenergy calibrations provide a rapid, cost-effective method to accurately estimate Switchgrass cell wall composition. A non-funded cooperative agreement between the USDA-ARS and the Near Infrared Spectrometry Consortium (NIRSC) (http://nirsconsortium.org/default.aspx) has been established for the purpose of transferring the NIRS calibrations for Switchgrass composition to other public and private laboratories and to industries that are using or will use Switchgrass for biomass energy.
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Switchgrass Harvest and Storage
Green Energy and Technology, 2012Co-Authors: Robert B. Mitchell, Marty R. SchmerAbstract:The feedstock characteristics of the conversion platform will influence the optimal harvest and post harvest management practices for Switchgrass. However, many of the harvest management practices are tied to plant phenology and will be similar across platforms. Proper harvest and storage of Switchgrass will help provide a consistent and high-quality feedstock to the biorefinery. Bioenergy-specific Switchgrass strains are high-yielding and in most cases can be harvested and baled with commercially available haying equipment. Many options are available for packaging Switchgrass for storage and transportation, but large round bales or large rectangular bales are the most readily available and are in use on farms. Large round bales tend to have less storage losses than large rectangular bales when stored outside, but rectangular bales tend to be easier to handle and load a truck for transport without road width restrictions. Although there is limited large-scale experience with harvesting and storing Switchgrass for bioenergy, extensive research, as well as a history of harvesting hay crops for livestock in many agroecoregions, makes harvesting and preserving Switchgrass for bioenergy feasible at the landscape scale.
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Herbicides for Establishing Switchgrass in the Central and Northern Great Plains
BioEnergy Research, 2010Co-Authors: Robert B. Mitchell, Kenneth P. Vogel, John Berdahl, Robert A. MastersAbstract:Weed interference limits Switchgrass ( Panicum virgatum L.) establishment from seed. Our objectives were to determine the effect of selected post-plant, preemergence herbicides on stand establishment and subsequent biomass yields of adapted upland Switchgrass cultivars grown in three environments in the Central and Northern Great Plains. A separate experiment was conducted in eastern Nebraska to determine if there were any differences among Switchgrass ecotypes for herbicide tolerance to the optimal herbicide combination. Herbicides applied immediately after planting were different concentrations of atrazine [Aatrex 4L®; 6-chloro- N -ethyl- N ′-(1-methylethyl)-1,3,5-triazine-2,4-diamine], quinclorac (Paramount®; 3,7-Dichloro-8-quinolinecarboxylic acid), atrazine+quinclorac, imazapic {Plateau®; 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid}, and quinclorac+imazapic. Herbicide efficacy was determined by measuring stand frequency of occurrence and biomass yield the year after establishment. The application of quinclorac plus atrazine resulted in acceptable stands and high biomass yields. Imazapic often reduced Switchgrass stands in comparison to the nontreated control and is not recommended for Switchgrass establishment. In the multi-state trials, the herbicide by cultivar interaction was not significant for stands or biomass yields, indicating that the effects of herbicides on Switchgrass stands and biomass yields were consistent over the upland cultivars used in the trials. No differences were detected among Switchgrass lowland and upland ecotypes for tolerance to atrazine and quinclorac. Quinclorac, which provides effective control of grassy weeds, and herbicides such as atrazine which provide good broadleaf weed control are an excellent herbicide combination for establishing Switchgrass for biomass production in the Great Plains and the Midwest.
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Managing and enhancing Switchgrass as a bioenergy feedstock
Biofuels Bioproducts and Biorefining, 2008Co-Authors: Robert B. Mitchell, Kenneth P. Vogel, Gautam SarathAbstract:The United States Department of Energy (DOE) has identifi ed Switchgrass (Panicum virgatum L.) as a viable perennial herbaceous feedstock for cellulosic ethanol production. Although Switchgrass bioenergy research was initi- ated by USDA-ARS, Lincoln, NE, USA in 1990, Switchgrass research has been conducted at this location since the 1930s. Consequently, a signifi cant amount of genetic and agronomic research on Switchgrass has been conducted for the Corn Belt and Central Great Plains of the USA that is directly applicable to its use as a biomass energy crop. Simi- lar research must be conducted in other major agroecoregions to verify or modify Switchgrass management practices (agronomics) for bioenergy production. The technology to utilize Switchgrass for producing ethanol using a cellulosic platform or by pyrolysis to generate syngas is advancing rapidly. Regardless of platform, using Switchgrass for ethanol production will require the development of improved bioenergy cultivars or hybrids and improved agronomics to opti- mize production and will introduce competing uses for the land base. Published in 2008 by John Wiley & Sons, Ltd
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net energy of cellulosic ethanol from Switchgrass
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Marty R. Schmer, Kenneth P. Vogel, Robert B. Mitchell, Richard K. PerrinAbstract:Perennial herbaceous plants such as Switchgrass (Panicum virgatum L.) are being evaluated as cellulosic bioenergy crops. Two major concerns have been the net energy efficiency and economic feasibility of Switchgrass and similar crops. All previous energy analyses have been based on data from research plots (<5 m2) and estimated inputs. We managed Switchgrass as a biomass energy crop in field trials of 3–9 ha (1 ha = 10,000 m2) on marginal cropland on 10 farms across a wide precipitation and temperature gradient in the midcontinental U.S. to determine net energy and economic costs based on known farm inputs and harvested yields. In this report, we summarize the agricultural energy input costs, biomass yield, estimated ethanol output, greenhouse gas emissions, and net energy results. Annual biomass yields of established fields averaged 5.2 -11.1 Mg·ha−1 with a resulting average estimated net energy yield (NEY) of 60 GJ·ha−1·y−1. Switchgrass produced 540% more renewable than nonrenewable energy consumed. Switchgrass monocultures managed for high yield produced 93% more biomass yield and an equivalent estimated NEY than previous estimates from human-made prairies that received low agricultural inputs. Estimated average greenhouse gas (GHG) emissions from cellulosic ethanol derived from Switchgrass were 94% lower than estimated GHG from gasoline. This is a baseline study that represents the genetic material and agronomic technology available for Switchgrass production in 2000 and 2001, when the fields were planted. Improved genetics and agronomics may further enhance energy sustainability and biofuel yield of Switchgrass.
Kenneth P. Vogel - One of the best experts on this subject based on the ideXlab platform.
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Herbicides for Establishing Switchgrass in the Central and Northern Great Plains
BioEnergy Research, 2010Co-Authors: Robert B. Mitchell, Kenneth P. Vogel, John Berdahl, Robert A. MastersAbstract:Weed interference limits Switchgrass ( Panicum virgatum L.) establishment from seed. Our objectives were to determine the effect of selected post-plant, preemergence herbicides on stand establishment and subsequent biomass yields of adapted upland Switchgrass cultivars grown in three environments in the Central and Northern Great Plains. A separate experiment was conducted in eastern Nebraska to determine if there were any differences among Switchgrass ecotypes for herbicide tolerance to the optimal herbicide combination. Herbicides applied immediately after planting were different concentrations of atrazine [Aatrex 4L®; 6-chloro- N -ethyl- N ′-(1-methylethyl)-1,3,5-triazine-2,4-diamine], quinclorac (Paramount®; 3,7-Dichloro-8-quinolinecarboxylic acid), atrazine+quinclorac, imazapic {Plateau®; 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid}, and quinclorac+imazapic. Herbicide efficacy was determined by measuring stand frequency of occurrence and biomass yield the year after establishment. The application of quinclorac plus atrazine resulted in acceptable stands and high biomass yields. Imazapic often reduced Switchgrass stands in comparison to the nontreated control and is not recommended for Switchgrass establishment. In the multi-state trials, the herbicide by cultivar interaction was not significant for stands or biomass yields, indicating that the effects of herbicides on Switchgrass stands and biomass yields were consistent over the upland cultivars used in the trials. No differences were detected among Switchgrass lowland and upland ecotypes for tolerance to atrazine and quinclorac. Quinclorac, which provides effective control of grassy weeds, and herbicides such as atrazine which provide good broadleaf weed control are an excellent herbicide combination for establishing Switchgrass for biomass production in the Great Plains and the Midwest.
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Managing and enhancing Switchgrass as a bioenergy feedstock
Biofuels Bioproducts and Biorefining, 2008Co-Authors: Robert B. Mitchell, Kenneth P. Vogel, Gautam SarathAbstract:The United States Department of Energy (DOE) has identifi ed Switchgrass (Panicum virgatum L.) as a viable perennial herbaceous feedstock for cellulosic ethanol production. Although Switchgrass bioenergy research was initi- ated by USDA-ARS, Lincoln, NE, USA in 1990, Switchgrass research has been conducted at this location since the 1930s. Consequently, a signifi cant amount of genetic and agronomic research on Switchgrass has been conducted for the Corn Belt and Central Great Plains of the USA that is directly applicable to its use as a biomass energy crop. Simi- lar research must be conducted in other major agroecoregions to verify or modify Switchgrass management practices (agronomics) for bioenergy production. The technology to utilize Switchgrass for producing ethanol using a cellulosic platform or by pyrolysis to generate syngas is advancing rapidly. Regardless of platform, using Switchgrass for ethanol production will require the development of improved bioenergy cultivars or hybrids and improved agronomics to opti- mize production and will introduce competing uses for the land base. Published in 2008 by John Wiley & Sons, Ltd
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net energy of cellulosic ethanol from Switchgrass
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Marty R. Schmer, Kenneth P. Vogel, Robert B. Mitchell, Richard K. PerrinAbstract:Perennial herbaceous plants such as Switchgrass (Panicum virgatum L.) are being evaluated as cellulosic bioenergy crops. Two major concerns have been the net energy efficiency and economic feasibility of Switchgrass and similar crops. All previous energy analyses have been based on data from research plots (<5 m2) and estimated inputs. We managed Switchgrass as a biomass energy crop in field trials of 3–9 ha (1 ha = 10,000 m2) on marginal cropland on 10 farms across a wide precipitation and temperature gradient in the midcontinental U.S. to determine net energy and economic costs based on known farm inputs and harvested yields. In this report, we summarize the agricultural energy input costs, biomass yield, estimated ethanol output, greenhouse gas emissions, and net energy results. Annual biomass yields of established fields averaged 5.2 -11.1 Mg·ha−1 with a resulting average estimated net energy yield (NEY) of 60 GJ·ha−1·y−1. Switchgrass produced 540% more renewable than nonrenewable energy consumed. Switchgrass monocultures managed for high yield produced 93% more biomass yield and an equivalent estimated NEY than previous estimates from human-made prairies that received low agricultural inputs. Estimated average greenhouse gas (GHG) emissions from cellulosic ethanol derived from Switchgrass were 94% lower than estimated GHG from gasoline. This is a baseline study that represents the genetic material and agronomic technology available for Switchgrass production in 2000 and 2001, when the fields were planted. Improved genetics and agronomics may further enhance energy sustainability and biofuel yield of Switchgrass.
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net energy of cellulosic ethanol from Switchgrass
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Marty R. Schmer, Kenneth P. Vogel, Robert B. Mitchell, Richard K. PerrinAbstract:Abstract Perennial herbaceous plants such as Switchgrass (Panicum virgatum L.) are being evaluated as cellulosic bioenergy crops. Two major concerns have been the net energy efficiency and economic feasibility of Switchgrass and similar crops. All previous energy analyses have been based on data from research plots (<5 m2) and estimated inputs. We managed Switchgrass as a biomass energy crop in field trials of 3–9 ha (1 ha = 10,000 m2) on marginal cropland on 10 farms across a wide precipitation and temperature gradient in the midcontinental U.S. to determine net energy and economic costs based on known farm inputs and harvested yields. In this report, we summarize the agricultural energy input costs, biomass yield, estimated ethanol output, greenhouse gas emissions, and net energy results. Annual biomass yields of established fields averaged 5.2 -11.1 Mg·ha−1 with a resulting average estimated net energy yield (NEY) of 60 GJ·ha−1·y−1. Switchgrass produced 540% more renewable than nonrenewable energy consumed. Switchgrass monocultures managed for high yield produced 93% more biomass yield and an equivalent estimated NEY than previous estimates from human-made prairies that received low agricultural inputs. Estimated average greenhouse gas (GHG) emissions from cellulosic ethanol derived from Switchgrass were 94% lower than estimated GHG from gasoline. This is a baseline study that represents the genetic material and agronomic technology available for Switchgrass production in 2000 and 2001, when the fields were planted. Improved genetics and agronomics may further enhance energy sustainability and biofuel yield of Switchgrass. agriculture bioenergy biomass biomass energy greenhouse gas
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Development of Switchgrass into a biomass energy crop
2008Co-Authors: Kenneth P. Vogel, Robert B. Mitchell, Guatam SarathAbstract:Switchgrass (Panicum virgatum L.) is a North American prairie grass that is being developed into a biomass energy crop in the United States and other countries. Research on Switchgrass as a pasture and forage crop was initiated in the mid-1930s in a USDA and University of Nebraska cooperative program. In 1990, breeding and management research also was initiated to develop Switchgrass into a biomass energy crop. Critical questions for a biomass/bioenergy production system include: What are the economics? Is energy from biomass net energy-positive? Is production system information available and verifi ed? Is the system sustainable? To address these questions, 10 farmers in the midcontinental United States were contracted to grow Switchgrass in 6-8 ha fi elds for a 5-year period and manage it as a biomass energy crop using available cultivars and management practices from 2000 to 2005. Results indicate that during this period Switchgrass biomass feedstock could have been produced in this region at a cost of about $50 Mg at the farm gate, which translates to about $0.13 per liter of ethanol. Net energy yield on the established Switchgrass fi elds was 60 GJ ha y. In these farmer trials, Switchgrass produced 540 percent more renewable energy than nonrenewable energy consumed. Th ese baseline studies represent the technology that was available for Switchgrass in 2000 and 2001 when the fi elds were planted but clearly demonstrate that for Switchgrass a full array of production system technology is available for its use as a biomass energy crop. Improved genetics and agronomics will further enhance energy sustainability and biofuel yield of Switchgrass. Carbon sequestration research is still in progress, but the initial results are very encouraging. Technology has been developed to rotate from Switchgrass to crops including maize and soybeans and back to Switchgrass without plowing.
John S. King - One of the best experts on this subject based on the ideXlab platform.
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Switchgrass growth and pine–Switchgrass interactions in established intercropping systems
Gcb Bioenergy, 2016Co-Authors: Shiying Tian, Julian F. Cacho, Mohamed A. Youssef, George M. Chescheir, Milan Fischer, Jami E. Nettles, John S. KingAbstract:Intercropping Switchgrass (Panicum virgatum L.) with loblolly pine (Pinus taeda L.) has been proposed for producing bioenergy feedstock in the southeastern United States. This study investigated Switchgrass growth and pine–Switchgrass interactions at two established experimental fields (7-year-old Lenoir site and 5-year-old Carteret site) located on the coastal plain of eastern United States. Position effects (edge and center of Switchgrass alley in intercropping plots) and treatment effects (intercropping vs. grass-only) on aboveground Switchgrass growth were evaluated. Interspecific interactions with respect to capturing resources (light, soil water, and nitrogen) were investigated by measuring photosynthetically active radiation (PAR) above grass canopy, soil moisture, and soil mineral nitrogen contents. Switchgrass growth was significantly (P = 0.001) affected by treatments in Lenoir and by position (P
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Gas exchange and stand-level estimates of water use and gross primary productivity in an experimental pine and Switchgrass intercrop forestry system on the Lower Coastal Plain of North Carolina, U.S.A
Agricultural and Forest Meteorology, 2014Co-Authors: Janine M. Albaugh, Eric B. Sucre, Zakiya H. Leggett, Jean-christophe Domec, Chris A. Maier, John S. KingAbstract:Despite growing interest in using Switchgrass (Panicum virgatum L.) as a biofuel, there are limited data on the physiology of this species and its effect on stand water use and carbon (C) assimilation when grown as a forest intercrop for bioenergy. Therefore, we quantified gas exchange rates of Switchgrass within intercropped plots and in pure Switchgrass plots during its second growing season in an intensively managed loblolly pine (Pinus taeda L.) plantation in North Carolina. Switchgrass physiology was characterized over the growing season from June to October 2010 in terms of photosynthesis (μmol m−2 s−1), stomatal conductance (mmol m−2 s−1), and assimilation responses to photosynthetic photon flux density and intercellular carbon dioxide concentration (CO2). We then used a process-based model of the soil–plant–atmosphere continuum to scale leaf-level gas exchange data to provide estimates of pine and Switchgrass stand-level water use (mm) and carbon exchange (g C m−2) over a three-year period. Peak Switchgrass photosynthesis (32.7 ± 0.9 μmol m−2 s−1) and stomatal conductance (252 ± 12 mmol m−2 s−1) rates were measured in July, with minimum values (18.7 ± 1.4 μmol m−2 s−1 and 104 ± 6 mmol m−2 s−1, respectively) recorded at the end of the growing season (October). Switchgrass gas exchange and parameter estimates from the light- and CO2 response curves did not vary between treatments. However, gas exchange values differed significantly between measurement dates. Model predictions of stand-level transpiration ranged from 287 to 431 mm year−1 for pine and from 245 to 296 mm year−1 for Switchgrass. Annual C exchange for loblolly pine ranged from 1165 to 1903 g m−2 compared to 1386 to 1594 g m−2 for Switchgrass. At this stage of stand development, no effect of intercropping was evident and there was no effect of distance from the nearest pine row on any Switchgrass gas exchange variable measured. However, we anticipate that as this intercropped system develops over time, competition for resources such as light, water or nitrogen may change, with the potential to impact Switchgrass physiology and biomass production.
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Evaluation of intercropped Switchgrass establishment under a range of experimental site preparation treatments in a forested setting on the Lower Coastal Plain of North Carolina, U.S.A.
Biomass and Bioenergy, 2012Co-Authors: Janine M. Albaugh, Eric B. Sucre, Zakiya H. Leggett, Jean-christophe Domec, John S. KingAbstract:There is growing interest in using Switchgrass (Panicum virgatum L.) as a biofuel crop and for its potential to sequester carbon. However, there are limited data on the establishment success of this species when grown as a forest intercrop in coastal plain settings of the U.S. Southeast. Therefore, we studied establishment success of Switchgrass within experimental intercropped plots and in pure Switchgrass plots in an intensively managed loblolly pine (Pinus taeda) plantation in eastern North Carolina. Pine trees were planted in the winter of 2008, and Switchgrass was planted in the summer of 2009. Establishment success of Switchgrass was measured over the growing season from May to October 2010, and quantified in terms of percent cover, height (cm), tiller density (number of tillers m−2), leaf area index and biomass (Mg ha−1). At the end of the growing season, pure Switchgrass plots were taller than the intercropped treatments (114 ± 2 cm versus 98 ± 1 cm, respectively), but no significant treatment effects were evident in the other variables measured. Switchgrass biomass across all treatments increased from 2.65 ± 0.81 Mg ha−1 in 2009 to 4.14 ± 0.45 Mg ha−1 in 2010. There was no significant effect of distance from the pine row on any Switchgrass growth parameters. However, we anticipate a shading effect over time that may limit Switchgrass growth as the pines approach stand closure.
