High-biomass sorghums for biomass biofuel production

High-biomass sorghums provide structural carbohydrates for bioenergy production. Sorghum improvement is well established, but development of high-biomass sorghums for biofuels is not. Thus the objectives of this research were to develop information on sorghum improvement of high-biomass sorghums including marker-assisted selection, use of exotic germplasm, heterosis, and GxE variability of biomass composition.;Marker-assisted selection was compared to testcross selection for identifying photoperiod-insensitive (PI) experimental lines that yield photoperiod-sensitive (PS) hybrids within the Ma1/Ma5/Ma6 hybrid production system. Four hundred eighty-three sorghum lines were genotyped at the Ma1 and Ma5 loci to predict their hybrid photoperiod reactions and testcrossed to establish actual hybrid photoperiod reactions. Ma1/Ma5 marker selections for lines producing PI hybrids were reliable. Ma1/Ma5 marker selections for lines producing PS hybrids were not reliable and identification of such lines will require testcrossing or genotyping at Ma6 or other additional loci.;An attempt was made to determine whether relationships exist between the passport data (geographic origin) of sorghum accessions and high-biomass desirability. Such a relationship could prioritize sorghum accessions for breeding evaluations. Seventeen hundred ninety two exotic sorghum accessions from 7 different geographic origins were evaluated for high-biomass desirability in 3 environments. Significant relationships between passport data and high-biomass desirability were identified within environments, but not across environments because of large GxE interactions. A larger sampling of environments will be needed to establish reliable passport data and high-biomass desirability GxE patterns.;Hybrid entries derived from high-biomass sorghum pollinators and grain sorghum females were evaluated for biomass heterosis. Moderate levels of biomass high-parent heterosis were widely available in the hybrids. Heterosis and biomass yields were maximized in specific hybrid combinations and were subject to GxE interactions.;Biomass composition (% cellulose, hemicellulose, etc.) affects the conversion efficiency of biomass to fuel and may be subject to GxE interactions. The biomass composition of 12 sorghums grown across 5 environments was estimated using Near-Infrared Spectroscopy to identify GxE patterns. Significant GxE interactions for composition were identified. Differences between genotypes for compositional traits were small (1--3 %), but may prove important with large-scale biomass processing.