Luis Armando Rivera Burgos Sr., Agronomy, Purdue University, West Lafayette, IN and Gebisa Ejeta, Center for Global Food Security, Purdue University, West Lafayette, IN
Brown midrib sweet sorghum biomass for ethanol production
Threatened food security and energy supplies are two major global issues. Arable land, both in developed and developing counties, needs to produce enough food to feed the growing population. In addition to harvestable food, most crops also yield an appreciable amount of biomass that is often left unharvested. Much of the biomass could be used to meet the energy demands without diverting food sources to energy production through fermentation of cellulose and other waste carbon sources sequestered in crop biomass. Ethanol can be produced from cellulose and other complex carbohydrates not normally used as human food. Sorghum is an excellent dual propose crop capable of producing both grain for food and biomass as a fermentable energy source. Researchers at Purdue discovered certain mutations that improve biomass quality; thus, its fermentability to ethanol. These traits include brown midrib (reduced lignin) and sweet stalk (increased sugar in stem) and both can greatly increase biomass quality.
A two year trial of 236 brown midrib sweet sorghum RILs was conducted to assess biomass agronomic performance and quality. They were planted in a randomized block design with two replications at ACRE Purdue University. Biomass yield, grain yield, maturity, plant height, stem thickness, lodging score and degree brix were measured in both years. Similarly, Fiber Detergent Analysis was performed to estimate NDA, ADF and ADL g/kg in stover. ANOVA analyses and means comparison were performed. A group of RILs performed very well for biomass yield, height, lodging score, degree brix and ADL% in both years. BLUPs of these traits were estimated and plugged into a regression analysis to obtain the best predictors of glucan recovery and ethanol yield. ADL (g/kg) and degree Brix were the best predictor for glucan recovery and theoretical ethanol yield in our brown midrib sweet sorghum RILs.