Greenhouse and Field Evaluation of Alamo and Two New Genotypes of Switchgrass for Biomass Production
Type of Degreethesis
Agronomy and Soils
MetadataShow full item record
Due to its high yields and wide geographic range, switchgrass (Panicum virgatum) was chosen by the Department of Energy as a model herbaceous perennial bioenergy feedstock. Alamo is the highest yielding variety, and the “benchmark” recommended for the Deep South. Within the species, and even within this variety, large amounts of genetic variability exist, allowing for the development of cultivars with higher yields, and composition better suited for the needs of either biochemical or thermochemical conversion methods, through selective breeding. Links between the physiological measurements during seedling growth and yield of the mature plant in the field are unknown, but could expedite breeding progress if they were available. Therefore, the objective of this study was to compare Alamo with two new genetic lines of switchgrass, GA-992 and GA-993, in a field study and a study of seedling growth in a greenhouse, to examine whether seedling growth in a greenhouse was indicative of yield and other differences in the field experiment. The field experiment compared yield, cell wall, C, and N composition, and morphological characteristics of the three genetic lines over a 4-year period. Growth of seedlings from each line was measured weekly over a seven-week period in the greenhouse experiment which was conducted twice in 2008. Root measurements and partitioning of C and N in the roots and shoots of the seedlings were also measured. Data from the greenhouse experiment revealed complex interactions, with little or no difference among genetic lines for most variables measured. Height and weight of the two new lines were superior to that of Alamo on certain harvest dates, but this pattern was not consistent over time, and was not detected in the field study where there was mostly no difference in biomass yield among experimental entries. It is concluded that differences among the three genetic lines evaluated in this research were small or not detectable, and results in the field experiment could not be predicted from results in the greenhouse experiment.