Download or read book Genetic Improvement of Biomass Yield in Upland Switchgrass Panicum Virgatum L Using Secondary Plant Morphological Traits written by and published by . This book was released on 2013 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: Switchgrass (Panicum virgatum L.) is currently undergoing intensive breeding efforts to improve biomass yield. Direct selection for biomass yield in switchgrass has proven difficult due to the many factors influencing biomass yield. In developing breeding schemes for increasing biomass yield, consideration must be made to the relative importance of spaced plantings to sward plots for evaluation and selection. It has previously been suggested that selection schemes using secondary plant morphological traits as selection criteria within spaced plantings may be an efficient method of making genetic gain. This research sought to identify secondary morphological traits in parental plants that are predictive of biomass yield in progeny swards, estimate heritability of secondary morphological traits and empirically test the effects of direct selection for secondary morphological traits on biomass yield. Limited predictive ability was observed for sward biomass yield using individual and combinations of plant morphological traits. A comparison of models using a Bayesian model averaging approach revealed common traits among the best predictive models including plant height, single-plant dry biomass, and second leaf width. Predictions of single-plant biomass, using the same set of morphological traits, revealed a large effect for tillering related traits. Moderate heritability was estimated for plant height and was greater for selection of increased height. Heritability for tiller count was low overall, with greater values observed for reduced tillering selections. Flowering date was estimated to have high heritability overall in both selection directions. Divergently selected populations for each trait were developed from the WS4U upland tetraploid germplasm and evaluated for biomass yield at five locations in Wisconsin during two growing seasons. Significant variation was observed between maternal parents of the selected populations for both selected and non-selected traits. Despite substantial differences between parent plant populations for plant morphology, significant differences were not observed for sward-plot biomass yield or sward-plot morphology relative to the base population. Results of this research demonstrate the challenges of selecting for increased biomass yield in switchgrass within spaced-plant nurseries. Based on these results it is recommended that greater emphasis be placed on evaluation biomass yield within sward plots for improving biomass yield.

Download or read book Evaluation of Traits Associated with Breeding for Improved Biomass and Ethanol Yield in Switchgrass written by Virginia Roseanna Sykes and published by . This book was released on 2014 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Switchgrass (Panicum virgatum L.) is a perennial, warm season grass that can be used as a biofuel. A greater understanding of the relationship of biomass yield and ethanol yield with disease susceptibility and morphological traits, estimation of the underlying genetic parameters of these traits, and the efficacy of selection at different maturity and under different production conditions could help breeders more effectively develop improved biofuel switchgrass cultivars. To examine these issues, three studies were performed. The first examined switchgrass leaves exhibiting low, medium, and high severity of rust symptoms, caused by infection with Puccinia emaculata. Results indicate P. emaculata infection may negatively impact ethanol yield in biofuels switchgrass with predicted ethanol yield reductions of 10% to 34% in leaves exhibiting medium rust severity and 21% to 51% in leaves exhibiting high rust severity. The second study analyzed a diallel of eight parents selected from the cultivars ‘Alamo’, ‘Kanlow’, and ‘Miami’. Correlations of morphological traits to biomass yield indicate a high biomass yielding ideotype of a tall plant with a high number of thick tillers, wide leaves, and an open canopy density. Traits with moderate correlations to biomass yield showed significant, but weak, negative correlations to ethanol yield. Significant SCA effects, maternal effects, and high parent heterosis were found within all traits. Selection during the establishment year did not differ significantly from selection in subsequent years. The third study used the same diallel populations but compared evaluations under space planted conditions to simulated swards. Evaluation under sward conditions differed from evaluation under space planted conditions for estimates of mean production performance, characterization of morphological traits, estimates of genetic parameters, identification of high GCA and SCA in populations, and identification of potential maternal effects or high parent heterosis. If sward conditions are more representative of production conditions, evaluation under space planted conditions could lead to assessment and selection of plants that are less than optimal in production conditions. Results from these three studies should help breeders identify more efficient and effective methods for improving biofuel switchgrass cultivars.

Download or read book Genetic Modification of Switchgrass Panicum Virgatum L for Improvement of Plant Architecture Biomass Productivity and Sugar Release Efficiency for Biofuel written by Wegi Aberra Wuddineh and published by . This book was released on 2015 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Switchgrass (Panicum virgatum L.) is a leading candidate bioenergy crop for sustainable biofuel production. To ensure its economic viability, tremendous improvements in switchgrass biomass productivity and recalcitrance to enzymatic saccharification are needed. Genetic manipulation of lignin biosynthesis by targeting transcriptional regulators of higher level domains of lignin biosynthesis and other complex traits could alter several bioenergy-desirable traits at once. A three-pronged approach was made in the dissertation research to target one plant growth regulator and transcription factors to alter plant architecture a nd cell wall biosynthesis. Gibberellin (GA) catabolic enzymes, GA 2-oxidases (GA2oxs), were utilized to alternatively modify the lignin biosynthesis pathway as GA is known to play a role in plant lignification. Constitutive overexpression of switchgrass C20 [C20] GA2ox genes altered plant morphology and modified plant architecture by increasing the number of tillers. Moreover, transgenic plants exhibited reduced lignin especially in leaves accompanied by 15% increase in sugar release (glucose). The Knotted1 (PvKN1) TF, a putative repressor of lignin biosynthesis genes, was identified and evaluated for improving biomass characteristics of switchgrass for biofuel. Its ectopic overexpression in switchgrass altered the expression of genes in the lignin, cellulose and hemicellulose biosynthesis, and GA signalling pathways. Consequently, transgenic lines displayed altered growth phenotypes particularly at early stages of vegetative development and moderate changes in lignin content accompanied by improved sugar release by up to 16%. The APETALA2/ ethylene responsive factor (AP2/ERF) TFs are key putative targets for engineering plants not only so they can withstand adverse environmental factors but also confer modified cell wall characteristics. To facilitate this, a total of 207 switchgrass AP2/ERF TFs comprising 3 families (AP2, ERF and related to API3/VP (RAV)) were identified. Sequence analysis for conserved putative motifs and expression pattern analysis delimited key genes for manipulation of switchgrass. To that end, the PvERF001 TF gene was ectopically overexpressed resulting in improved biomass yield and sugar release efficiency. The transgenic plants and knowledge produced in this research will be used to create new lines of switchgrass with combined novel traits to address needs in biofuel production and sustainable plant cultivation to enable the development of the bioeconomy.

Download or read book Compendium of Bioenergy Plants written by Hong Luo and published by CRC Press. This book was released on 2014-03-14 with total page 463 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the most comprehensive reviews on the latest development of switchgrass research including the agronomy of the plant, the use of endophytes and mycorrhizae for biomass production, genetics and breeding of bioenergy related traits, molecular genetics and molecular breeding, genomics, transgenics, processing, bioconversion, biosyst

Download or read book Switchgrass written by Andrea Monti and published by Springer Science & Business Media. This book was released on 2012-03-09 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: The demand for renewable energies from biomass is growing steadily as policies are enacted to encourage such development and as industry increasingly sees an opportunity to develop bio-energy enterprises. Recent policy changes in the EU, USA and other countries are spurring interest in the cultivation of energy crops such as switchgrass. Switchgrass has gained and early lead in the race to find a biomass feedstock for energy production (and for the almost requisite need for bio-based products from such feedstocks). Switchgrass: A Valuable Biomass Crop for Energy provides a comprehensive guide to the biology, physiology, breeding, culture and conversion of switchgrass as well as highlighting various environmental, economic and social benefits. Considering this potential energy source, Switchgrass: A Valuable Biomass Crop for Energy brings together chapters from a range of experts in the field, including a foreword from Kenneth P. Vogel, to collect and present the environmental benefits and characteristics of this a crop with the potential to mitigate the risks of global warming by replacing fossil fuels. Including clear figures and tables to support discussions, Switchgrass: A Valuable Biomass Crop for Energy provides a solid reference for anyone with interest or investment in the development of bioenergy; researchers, policy makers and stakeholders will find this a key resource.

Download or read book Evaluation of Swicthgrass Panicum Virgatum L as a Bioenergy Feedstock for the Northeastern and Mid Atlantic USA written by Laura Mary Cortese and published by . This book was released on 2014 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Switchgrass (Panicum virgatum L.) is a warm season, C4 perennial grass native to most of North America with numerous applications, including use as a bioenergy feedstock. Although switchgrass has emerged as a bioenergy crop throughout the midwestern and southern US, little information is available on the performance of switchgrass in the Northeast/Mid-Atlantic. In the first genetic diversity study of switchgrass populations to utilize both morphological and molecular markers, it was found that the combination of morphological and molecular markers differentiated populations best, and should be useful in future applications such as genetic diversity studies, plant variety protection, and cultivar identification. In a study that evaluated several bioenergy traits of 10 switchgrass cultivars in NJ, populations with improved agronomic characteristics were identified. Cultivar Timber exhibited the best combination of characteristics and has promise for biomass production in the Northeast/Mid-Atlantic US. In a third study, the effects of cultivar, location, and harvest date on biomass yield, dry matter, ash, and combustion energy content in three switchgrass cultivars were investigated. Results indicated that a January harvest allowed for optimal feedstock quality and that cultivars Alamo, Carthage, and Timber produced high yielding, high quality biomass. In an effort to improve the establishment capacity of switchgrass, a fourth study was conducted examining the effects of divergent selection for seed weight on germination and emergence in three switchgrass populations over two cycles of selection, and cold stratification on germination in the derived populations. Selection for seed weight alone was not sufficient to improve germination and germination rate in populations tested, while cold stratification improved germination. Therefore, breeding efforts should be directed towards reducing dormancy in order to improve switchgrass germination and establishment. The final two studies examined genotype x environment effects, estimated broad-sense heritability, and stability analysis on lignocellulosic and agronomic traits in switchgrass clones grown on marginal and prime soils in NJ. Results support the existence of both specifically and broadly adapted switchgrass germplasm, and demonstrate the need for evaluation of germplasm across multiple years and environments (including prime and marginal sites) in order to develop cultivars with optimal lignocellulosic and agronomic characteristics.

Download or read book The Improvement of Yield Limiting Switchgrass Panicum Virgatum L Traits Through Genomic Prediction and Selection written by Neal Wepking Tilhou and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Genomic prediction allows the estimation of breeding values for individuals in a breeding program using molecular markers. In plant breeding, this can improve the precision of field evaluations or even allow a breeder to bypass time-intensive field evaluations altogether. Switchgrass is a candidate bioenergy crop which must be rapidly developed and deployed to mitigate climate change caused by excess carbon emissions. Switchgrass is a long-lived perennial with slow selection cycles (4-6 years), therefore accurate genomic prediction of yield or yield surrogates will be valuable for rapid cultivar development. This dissertation presents multiple applications of genomic prediction which can accelerate yield improvement in switchgrass. The first chapter is a review of recent developments of bioenergy, switchgrass agronomy, and genomic prediction. The second chapter evaluates genomic prediction of flowering time to improve biomass yield. It found limited value in sharing information between diverged switchgrass breeding populations, but that genomic prediction within breeding populations had strong predictive ability (0-43-0.90) and flowering time predictions were able to accurately rank individuals evaluated for biomass yield (0.38-0.63). The third chapter evaluated genomic prediction for winter survivorship on crosses from diverse, winter-intolerant populations. Again, genomic prediction was able to accurately predict winter survivorship in a progeny population (predictive ability = 0.71) and this chapter further reinforced that winter tolerant populations from the southern United States have strong biomass yield potential in the north-central United States. The fourth chapter presents simulations which tested pooled sequencing of DNA samples as a strategy to reduce the expense of adopting genomic prediction. Overall, pooling samples of individuals evaluated in the field and individuals sequenced to obtain predictions consistently resulted in reduced predictive ability. However, this loss in accuracy was often minor relative to the substantial cost savings provided by pooled DNA sequencing. In resource constrained scenarios, this study found multiple routes where DNA pooling could increase breeding progress. The research presented in this dissertation highlights multiple new breeding strategies and methods for integrating genomic prediction methods into switchgrass and other breeding programs with limited resources.

Download or read book Evaluating the Agronomic Performance of Switchgrass Panicum Virgatum L on Marginal Vs Prime Farmland written by Sergio J. Sosa and published by . This book was released on 2013 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: Switchgrass (Panicum virgatum L.) is a warm-season perennial grass native to North America. The difference in biomass production between and within switchgrass ecotypes (upland and lowland) and populations due to genotype x environment interaction (GxE) has been documented. Breeding research for increased biomass production in switchgrass has been conducted on University research farms with prime farmland. This study aims to evaluate the agronomic performance of 14 cultivars and 45 high biomass producing clones of switchgrass in marginal vs. prime farmland. Additionally this study investigates the effects of increasing biodiversity (1 grass species, 3 grass species or 4 species-grass/legume combinations) on biomass production. The cultivars and biodiversity studies were seeded in 2008 and 2009 in six locations (Maryland, New Jersey, New York, Pennsylvania, South Dakota and Wisconsin) and three locations (New Jersey, New York, Pennsylvania), respectively, in paired fields (marginal vs. prime land). Each field had a nitrogen treatment 0 or 100 kg of N·ha-1·year-1. Stand establishment (% coverage), plant height (cm), tiller density (tillers·m-2) and dry biomass yield (Mg·ha-1) data was collected to determine agronomic performance. The clonal material was transplanted in 2009 in two locations (New Jersey and South Dakota). In addition to agronomic data collected, heading date, anthesis date (Julian date) and visual ratings for disease presence were recorded. Cultivars were shorter in marginal soils. For stand establishment and biomass yield, 50% of cultivars showed differences due to soil quality. For tiller density, 40% of the cultivars presented differences due to soil quality; some cultivars had higher tiller density in marginal soils. For the biodiversity study low diversity plots (one grass species) were not significantly different than yields of high diversity plots (four species-grass/legume). For the clone study, soil quality may have influenced a delay in flower initiation and other traits, such as plant height, etc. It was also observed that genotype may have been the most influential factor in tolerance to anthracnose (Colletotrichum navitas) and rust (Puccinia emaculata).

Download or read book Hybridization of Downregulated COMT Transgenic Switchgrass Lines with Field selected Switchgrass for Improved Biomass Traits written by and published by . This book was released on 2016 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transgenic switchgrass (Panicum virgatum L.) has been produced for improved cell walls for biofuels. For instance, downregulated caffeic acid 3-O-methyltransferase (COMT) switchgrass produced significantly more biomass and biofuel than the non-transgenic progenitor line. In this present study we sought to further improve biomass characteristics by crossing the downregulated COMT T1 lines with high-yielding switchgrass accessions in two genetic backgrounds ('Alamo' and 'Kanlow'). Crosses and T2 progeny analyses were made under greenhouse conditions to assess maternal effects, plant morphology and yield, and cell wall traits. Female parent type influenced morphology, but had no effect on cell wall traits. T2 hybrids produced with T1 COMT-downregulated switchgrass as the female parent were taller, produced more tillers, and produced 63% more biomass compared with those produced using the field selected accession as the female parent. Transgene status (presence or absence of transgene) influenced both growth and cell wall traits. T2 transgenic hybrids were 7% shorter 80 days after sowing and produced 43% less biomass than non-transgenic null-segregant hybrids. Cell wall-related differences included lower lignin content, reduced syringyl-to-guaiacyl (S/G) lignin monomer ratio, and a 12% increase in total sugar release in the T2 transgenic hybrids compared to non-transgenic null segregants. This is the first study to evaluate the feasibility of transferring the low-recalcitrance traits associated with a transgenic switchgrass line into high-yielding field varieties in an attempt to improve growth-related traits. Lastly, our results provide insights into the possible improvement of switchgrass productivity via biotechnology paired with plant breeding.

Download or read book Genetic Diversity Genetic Variation and Identification of Quantitative Trait Loci QTL Associated with Biomass Yield and Establishment related Traits in Lowland Switchgrass Panicum Virgatum L written by Cheryl Ontolan Dalid and published by . This book was released on 2018 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: Switchgrass is a warm-season C4 grass used for biofuel production. The primary goal of this study is biomass yield improvement for use as a bioenergy feedstock. The research plan was partitioned into three main objectives: (i) evaluate the genetic diversity among lowland switchgrass populations using microsatellite markers; (ii) assess genetic variation in an Alamo half-sib (AHS) population developed through phenotypic selection; (iii) and identify quantitative trait loci (QTL) associated with biomass yield and establishment related seed traits using a Nested Association Mapping (NAM) population. The genetic diversity study on lowland switchgrass showed significant phenotypic variations (P

Download or read book Deciphering Natural Allelic Variation in Switchgrass for Biomass Yield and Quality Using a Nested Association Mapping Population written by and published by . This book was released on 2016 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Assessing Best Management Practices for Improving Switchgrass Establishment and Production written by Amir Sadeghpour and published by . This book was released on 2014 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: Switchgrass (Panicum virgatum L.) is a C4-grass indigenous to North America being considered as the "model" energy crop. Switchgrass is difficult to establish and first-year stand failure often challenge the large scale production of switchgrass. Reliable establishment methods and effective weed management practices to produce a harvestable biomass in the establishment year are required. Also, to maximize the economic viability of switchgrass production, appropriate nutrient management and harvests are needed. Thus, we conducted researches to improve switchgrass establishment and production. These studies ranged from finding the most promising switchgrass variety to adjusting switchgrass seeding rate, determine the most appropriate seeding date, seeding methods, weed management, nitrogen application, and harvest management. Currently Cave-in-Rock is a highly suggested upland variety for northern region of United States. Results of our variety trials both at establishment and production level indicated that Carthage and Shawnee could also be considered as promising varieties in northern regions of United States. In a four-year study, Carthage consistently produced higher biomass yield compared with other varieties. A vigor test trial was suggested for adjusting switchgrass seeding rate and we found significant differences between the required seeding rate for producing acceptable first-year biomass in fertile soils and marginal soils. While approximately 7 kg ha-1 seeding rate might be sufficient for fertile soils, 14 kg ha-1 might be required to produce enough established seedling for the same biomass production in a marginal soil. An early planting of switchgrass was not as effective as a late planting in weed suppression but plants were more advanced morphologically thus, produced acceptable biomass yield with root system which ensures successful second-year production. Among cover crops, oat outperformed others (Fallow and Rye) with both suppressing weeds and improving switchgrass establishment. Results suggested drastic differences between no-till planting and seeding with cultipacker seeder where no-till planting into oat produced significantly higher biomass yield compared with cultipacker seeder. A firm seedbed is also another desirable method of planting where significantly improved switchgrass establishment and production was observed with 2 times rolling/cultipacking after seeding. Our findings indicated that application of herbicides is strongly required in the establishment year where a Broad Spectrum application of atrazine, quinclorac, 2,4-D, and dicamba improved switchgrass establishment through effective control of weeds. We found a late-fall harvest could improve switchgrass quality for combustion (less moisture, ash, and nutrient content) without yield reduction for many years. When switchgrass was harvested in late-fall, no response to N application was found. Overall, it is proposed that a no-till planting of switchgrass into oat cover crop with herbicide application planted in early-June could provide a successful stand and later, a late-fall harvest without any N application could maintain crop productivity with acceptable biomass yield and quality for several years.

Download or read book Identification and Overexpression of a Knotted1 like Transcription Factor in Switchgrass Panicum Virgatum L for Lignocellulosic Feedstock Improvement written by and published by . This book was released on 2016 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: High biomass production and wide adaptation has made switchgrass (Panicum virgatum L.) an important candidate lignocellulosic bioenergy crop. One major limitation of this and other lignocellulosic feedstocks is the recalcitrance of complex carbohydrates to hydrolysis for conversion to biofuels. Lignin is the major contributor to recalcitrance as it limits the accessibility of cell wall carbohydrates to enzymatic breakdown into fermentable sugars. Therefore, genetic manipulation of the lignin biosynthesis pathway is one strategy to reduce recalcitrance. Here, we identified a switchgrass Knotted1 transcription factor, PvKN1, with the aim of genetically engineering switchgrass for reduced biomass recalcitrance for biofuel production. Gene expression of the endogenous PvKN1 gene was observed to be highest in young inflorescences and stems. Ectopic overexpression of PvKN1 in switchgrass altered growth, especially in early developmental stages. Transgenic lines had reduced expression of most lignin biosynthetic genes accompanied by a reduction in lignin content suggesting the involvement of PvKN1 in the broad regulation of the lignin biosynthesis pathway. Moreover, the reduced expression of the Gibberellin 20-oxidase (GA20ox) gene in tandem with the increased expression of Gibberellin 2-oxidase (GA2ox) genes in transgenic PvKN1 lines suggest that PvKN1 may exert regulatory effects via modulation of GA signaling. Furthermore, overexpression of PvKN1 altered the expression of cellulose and hemicellulose biosynthetic genes and increased sugar release efficiency in transgenic lines. Our findings demonstrated that switchgrass PvKN1 is a putative ortholog of maize KN1 that is linked to plant lignification and cell wall and development traits as a major regulatory gene. Therefore, targeted overexpression of PvKN1 in bioenergy feedstocks may provide one feasible strategy for reducing biomass recalcitrance and simultaneously improving plant growth characteristics.

Download or read book Inference of Candidate Causal Variants and Assessment of Genomic Prediction for Bioenergy Traits in Switchgrass Panicum Virgatum L written by Guillaume Paul Ramstein and published by . This book was released on 2017 with total page 295 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular breeding based on DNA markers has the potential to accelerate genetic gains in switchgrass, a perennial grass and potential source of bioenergy feedstock in the eastern half of the United States. Though this species shows promise for energy production, substantial genetic gains for yield and quality are still critical for viability of switchgrass-based industries. In this dissertation, the prospect of using DNA markers in switchgrass breeding is studied under two modelling approaches: either using association models based on few significant markers, or using prediction models based on genome-wide marker information. The first chapter provides an overview on switchgrass as a potential bioenergy crop and introduces concepts and challenges related to improvement for biomass yield and quality traits in this species. The second chapter reports a genome-wide association study on a diverse panel in switchgrass and introduces methods for prioritizing pairs of markers for subsequent testing of marker-by-marker interactions. A total of 12 additive and interactive effects were identified for plant height, carbon content and mineral concentration. The third chapter reports an empirical assessment of genomic prediction in two switchgrass breeding panels and introduces methods to account for redundancy in marker information under such models. Good prediction accuracies were achieved, most notably for biomass yield in one of the breeding panels, and significant gain in prediction accuracy was achieved in one of the cases studied by accounting for redundancy in marker information. The last chapter of this dissertation assesses existing and novel methods for accommodating population heterogeneity in genomic prediction models, under three different strategies: ignoring, reducing or modelling interactions between markers and populations. While ignoring interactions was often not detrimental to accuracy, reducing interactions by selecting a diverse subset of individuals proved useful under conditions of restricted sample sizes, and modelling interactions proved beneficial to accuracy when the interactive model fitted the data substantially better than the standard models. The research presented in this disseration may contribute to general methodologies related to genetic analyses and should support further studies on the optimization of prediction models and the dissection of genetic architecture for bioenergy traits in switchgrass.

Download or read book Diallel Analysis of Biomass and Ethanol Yield in Leaves Versus Stems of Lowland Switchgrass written by Alexandria Christina DeSantis and published by . This book was released on 2015 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: Switchgrass (Panicum virgatum L.) is a warm season perennial grass used widely as a forage crop. This research seeks to address improving biomass yield and predicted ethanol yield through certain traits by the following objectives: (1) differences in average biomass and predicted ethanol yields from leaves versus stems, (2) genetic variance and heritability estimates of biomass and ethanol yield traits (3) general (GCA) and specific combining ability (SCA) among the five parents for biomass and ethanol yield, and (4) correlations between agronomic and morphological traits. Five parents with varying morphological traits were crossed in a diallel design, excluding selfs. Clonal replicates of all crosses were planted at ETREC in Knoxville, TN and PREC in Crossville, TN. The mean leaf biomass yield in 2012 was 22.9 g plant−1 [ grams per plant] and 15.2 g plant−1 at two locations. In 2013 mean values were 41.5 g plant−1 and 57.9 g plant−1. The mean stem biomass values were 29.4 g plant−1 and 15.6 g plant−1 in 2012. In 2013 the mean stem biomass yield increased to 84.6 g plant−1 and 98.6 g plant−1. The average leaf to plant ratio in 2012 was 0.55 and 0.37 in 2013. The mean for predicted leaf ethanol in 2012 was 65.8 mg g−1 DM [milligrams per gram dry matter] and was 68.4 mg g−1 DM in 2013. Predicted stem ethanol mean was 61.67 mg g−1 DM. GCA for leaf biomass ranged from -2.90 to 1.8 g plant−1, and SCA values ranged from -5.7 to 7.1. GCA values -7.8 to 9.2 g plant−1 for stem biomass yield, and SCA values ranged from -10.9 to 11.0 g plant−1. Predicted leaf ethanol yield GCA values ranged from -0.77 to 0.87, and SCA values ranged from -1.3 to 0.84. GCA values for predicted stem ethanol ranged from -3.2 to 2.6 mg g−1 DM, and SCA values from -1.2 to 1.3 mg g−1 DM. Narrow sense heritability estimates ranged from 0.03 to 0.23. Broad sense heritability estimates ranged from 0.16 to 0.6. High parent heterosis was observed in all traits. There were correlations between agronomic traits and morphological traits.

Download or read book Evaluation of Switchgrass M X Giganteus and Sorghum as Biomass Crops Effects of Environment and Field Management Practices written by Matthew W. Maughan and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Switchgrass (Panicum virgatum L.), Miscanthus x giganteus (M. x giganteus), and sorghum (Sorghum bicolor L.) have been proposed as potential bioenergy feedstock crops. This study evaluates how these crops performs in different environments under different crop management practices, particularly nitrogen (N) fertilizer rates. Chapter 1 provides the rationale of this research and a general discussion of the unique characteristics of these three crops. In Chapter 2, an extensive database of switchgrass biomass yields from 106 sites and 45 field studies in eastern two thirds of the USA and southeastern Canada is evaluated using descriptive statistics, and using a random coefficients model. Switchgrass has been researched extensively in North America as a biomass crop and data reported since the 19900́9s reveal large variability in dry biomass yields which are related to multiple environment and field management practices. This analysis describes switchgrass biomass N response, and shows that in addition to N fertilizer rate the most important factors affecting switchgrass dry biomass yields are growing region, spring precipitation, growing season, ecotype, and harvest timing. Chapter 3 remarks that studies reporting M. x giganteus dry biomass yields to date in the USA are few in number and little information is available to suggest a suitable growing region. This study investigates M. x giganteus in four Midwest and Atlantic Coast environments under three N rates. Establishment success, plant growth, morphology, and dry biomass yields were evaluated and results reveal no response to N rate during the establishment years, large biomass yield differences among environments, and decreased yield when the crop experienced a combination of high heat and dry conditions. Chapter 4 introduces two types of sorghum, forage sorghum and biomass sorghum (referred to as energy sorghum) which have been proposed as crops with high biomass production potential although prior to this study no research had evaluated these sorghum types grown for biomass in IL. This field study evaluated two forage sorghum and two energy sorghum hybrids in four IL environments under different N rates. Measurements of morphology and crop growth were measured throughout the growing season, and dry biomass yields revealed significant differences between the two sorghum types. The energy sorghum hybrids achieved the greatest biomass yields in each environment with the effects of environment and N rate affecting the biomass yields. The results of these studies provide valuable information for stakeholders, producers, and scientists regarding the impact of environment and management practices on biomass yields of switchgrass, M. x giganteus, and sorghum. It is necessary that these factors be evaluated prior to making decisions as to which crop species and which cultivar or hybrid to plant in a given location. In most cases, no regional recommendations for species selection and N fertility rates are adequate and most field management practices must be made on a site-by-site basis.

Download or read book Reproduction and Bioconfinement of MiR156 Transgenic Switchgrass Panicum Virgatum L written by Chelsea Renai Johnson and published by . This book was released on 2017 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: Genetic engineering of switchgrass (Panicum virgatum L.), an emerging cellulosic bioenergy feedstock, has been performed to alter cell walls for improved biofuel conversion. However, gene flow from transgenic switchgrass presents regulatory issues that may prevent commercialization of the genetically engineered crop in the eastern United States. Depending on its expression level, microRNA156 (miR156) can reduce, delay or eliminate flowering, which may be useful to mitigate transgene flow. However, flowering transition is dependent upon both environmental and genetic cues. In this study of transgenic switchgrass, two low (T14 and T35) and two medium (T27 and T37) miR156 overexpressing 'Alamo' lines and nontransgenic control plants were used. A two-year field experiment was performed to compare flowering, reproduction, and biomass yield in eastern Tennessee, U.S.A. Growth chamber studies assessed temperature and photoperiod effects on flowering and reproduction across a simulated latitudinal cline. In the field, medium miR156 overexpression line T37 resulted in the best overall combination of bioconfinement and biomass production. Though line T37 did flower, not all plants produced panicles, and panicle production was delayed in both years. Line T37 also produced fewer panicles, with a 65.9% reduction in year one and 23.8% reduction in year two over controls. T37 panicles produced 70.6% less flowers than control panicles during the second field year with commensurate decreased seed yield: 1205 seeds per plant vs. 18,539 produced by each control. These results are notable given that line T37 produced equivalent vegetative aboveground biomass as controls. In latitudinal simulation growth chambers, elevated temperatures and decreased daylength promoted flowering of the miR156 transgenic switchgrass lines. As temperatures increased and day lengths decreased, more plants in lines T35, T37, and controls produced panicles. The simulated (Ecuador) tropical conditions were the only chambers in which three of the four transgenic lines flowered. These results suggest that miR156 overexpression levels found in transgenic line T37 can be useful for bioconfinement, and the plants can significantly reproduce in tropical conditions, which would enable plant breeding for line improvement. Furthermore, the study suggests additional ways that miR156 can be manipulated to improve both biomass production and bioconfinement.