Winter Biomass Yield, Year-Round Elemental Concentrations of 'Kanlow' Switchgrass, and Associated Soil Nutrients in a Zero Input Environment

Switchgrass (Panicum virgatum L.) is a warm-season perennial species native to North America. It was selected by the U.S. Department of Energy (DOE) as the model herbaceous species for the development as a cellulosic feedstock crop for biofuels production. Maximum biomass yields in switchgrass can be harvested with one-cut system by mid-September. However, information is limited on winter biomass yield, elemental composition of standing cured biomass, and associated soil nutrient status. Therefore, the objectives of this study were to evaluate changes in winter biomass yield, year-round elemental composition of Kanlow switchgrass, and associated year-round soil nutrient dynamics in a zero input environment. An unfertilized Kanlow switchgrass planting established in 1998 was used in the study. The experimental design was a split plot randomized complete block design with 6 replications. The experimental treatment was monthly harvest from November to March in winter and year-round monthly sampling of biomass and soil for chemical analyses. The variable year was sub-plot within the main plot month. Each replication was on a large plot of 200 m2. The 2-yr mean dry matter yield of winter harvests was 5.13 t/ha, ranging from 3.88 t/ha in 2007-2008 to 6.38 t/ha in 2008-2009. Biomass yield decreased as winter progressed, statistically significant in first winter but not in the second winter. Concentrations of biomass elements and soil nutrients changed with various degrees over the two years. Biomass quality was not affected by harvesting `Kanlow' switchgrass from November to March as nutrient, ash, and cell wall components were not affected.Department of Plant and Soil Science

Aflp Genetic Variation, Inbreds Development, and Qtl Localization for Plant Height in Lowland Switchgrass

Switchgrass (Panicum virgatum L.) has gained wider attention due to its recognition as a model herbaceous crop species for bioenergy production. The objectives of this research were to analyze genetic variation among and within five lowland switchgrass cultivars using amplified fragment length polymorphism (AFLP) markers; to develop (i) S3 inbreds from S2 populations and (ii) S4 inbreds from S3 populations using a bagging method; and to analyze phenotypic variation for biomass and plant height and to localize QTLs associated with the plant height. AFLP polymorphisms indicated the presence of high genetic variation within lowland switchgrass cultivars. `Alamo' exhibited the highest genetic variation and `Performer' had the lowest. The Nei's genetic diversity parameters revealed the lowest genetic distance between cultivars `Alamo' and `Cimarron' and highest value between cultivars `Alamo' and `Kanlow'. Using 195 S2 inbreds, 279 S3 inbreds and 224 S4 inbreds were produced by bagging and confirmed with simple sequence repeat (SSR) markers. Two lowland switchgrass mapping populations field established at Perkins and Stillwater, OK were deployed in the plant height associated QTL experiment. Large genetic variation existed for plant biomass and height within the two populations. Plant height was positively correlated with biomass yield. Twenty-one QTLs were identified on 11 linkage groups, including nine of the QTL markers were detected in the selfed population and remaining 12 QTL markers were identified in the hybrid population. The findings of this research and the advanced inbreds developed in these experiments would be useful for future plant breeding and genetic improvement programs in lowland switchgrass.Plant & Soil Science

Switchgrass Biomass Yield and Fertilizer Requirements by Month of Harvest: Economic Consequences of Nutrient Translocation and Remobilization

If switchgrass harvest is delayed until after senescence, some nutrients will translocate to the plant’s crown and roots. Biomass yield and fertilizer requirements depend on harvest date. The objective is to determine switchgrass biomass yield, nutrient concentration in biomass, fertilizer requirements, and expected production cost by month of harvest

ELEMENTAL CONCENTRATIONS OF ‘KANLOW’ SWITCHGRASS, AND ASSOCIATED SOIL

committee chair, Dr. Yanqi Wu, for his continual guidance and support all the way through the completion of this thesis project. I am heartily thankful for his excellent teaching and encouragement that enabled me to undertake this research and complete it successfully. I would also like to express my gratitude to my committee members Dr. Hailin Zhang, Dr. Michael Anderson and Dr. Gopal Kakani for their valuable suggestions and contributions throughout the project and refining of this thesis. I am also thankful to Dr. Charles Taliaferro for his valuable suggestions. I would like to acknowledge and express sincere appreciation to Dr. Tim Samuels for his guidance and necessary arrangements for my study and research. Mr. Gary Williams and Ms. Sharon Williams deserve great acknowledgements for their participation all through the successful completion of this research work. I would like to thank the Department of Plant and Soil Sciences at Oklahoma State University for their permission to carry out this thesis project. I would also like to thank Oklahoma BioEnergy Center for funding this research. Finally, I would like to thank my family members and friends for their support in my academic pursuit

Yield-height correlation and QTL localization for plant height in two lowland switchgrass populations

Switchgrass (Panicum virgatum L.), as a model herbaceous crop species for bioenergy production, is targeted to improve biomass yield and feedstock quality. Plant height is a major component contributing to biomass yield. Accordingly, the objectives of this research were to analyze phenotypic variation for biomass and plant height and the association between them and to localize associated plant height QTLs. Two lowland switchgrass mapping populations, one selfed and another hybrid population established in the field at Perkins and Stillwater, Oklahoma, were deployed in the experiment for two years post establishment. Large genetic variation existed for plant biomass and height within the two populations. Plant height was positively correlated with biomass yield in the selfed population (r = 0.39, P<0.0001) and the hybrid population (r = 0.41, P<0.0001). In the selfed population, a joint analysis across all environments revealed 10 QTLs and separate analysis for each environment, collectively revealed 39 QTLs related to plant height. In the hybrid population, the joint analysis across overall environments revealed 35 QTLs and the separate analysis for each environment revealed 38 QTLs. The findings of this research contribute new information about the genetic control for plant height and will be useful for future plant breeding and genetic improvement programs in lowland switchgrass