The Effects of Cytoplasm on the Yield and Quality of Sorghum Biomass Hybrids

Abstract

The U.S. Renewable Fuel Standard mandated increases in the amount of renewable fuel blended into transportation fuel from 9 billion gallons in 2008 to 36 billion gallons by 2022. While a portion of this renewable fuel can be derived from corn-based ethanol, the remaining balance of fuel must come from second or third generation biofuel sources. Energy sorghum was identified as one of these potential sources and improvement to produce hybrid varieties thus commenced. One tool of hybrid sorghum development involves the use of cytoplasmic male-sterility (CMS). Since there are multiple CMS systems used in the production of hybrid sorghum, it is important to understand the effects each system has on the agronomic performance and composition of biomass energy sorghum. The purpose of this study is to determine if cytoplasm affects agronomic performance and the composition of biomass sorghum. Iso-cytoplasmic hybrids were produced using four female and four male parental lines, resulting in 16 hybrid genotypes in three different cytoplasms (A1, A2, and A3) for a total of 48 hybrids. These hybrids were evaluated in three environments over two years and measured traits included biomass yield, dry stalk yield, height, stalk juice yield, juice extraction efficiency, brix, ash, lignin, glucan, and xylan. For most all traits, differences among the hybrids and environments accounted for most of the variation; cytoplasm did not significantly affect the performance of any traits. These results indicate that the different CMS systems can be used interchangeably to make sorghum biomass energy hybrids without negative repercussions in terms of agronomic performance and composition.