Energy Sorghum

Researchers develop high-biomass sorghum that bypasses flowering
By Holly Jessen | November 15, 2011

What happens when sorghum doesn’t have to put energy into flowering and grain production? High-biomass sorghum that grows up to 20 feet tall, that’s what.

Texas AgriLife Research, part of the Texas A&M University System, is the home of hybrid sorghum, says Adam Helms, assistant program director. Researchers there recently identified a genetic marker to help develop high-biomass sorghum by prohibiting reproduction, or the flowering/grain stage, allowing that energy to go toward biomass accumulation. “This annually planted feedstock would add another tool to the toolbox for the producer,” he tells EPM. “When cellulosic ethanol conversion facilities become widespread, this feedstock would allow a producer to produce a grain, fiber or high-biomass crop.”

The sorghum hybrid accumulates as much as three times the amount of leaves and stems as grain sorghum. Among two 90-day-old plants,  a nonflowering high-biomass sorghum was 10 feet tall, while a typical grain sorghum variety was 3 feet tall. “That is a striking difference,” says Rebecca Murphy, a research team member and a biochemistry doctoral student at Texas A&M University.

Genetic mapping techniques were used to locate a genetic determinant of flowering time, first discovered by AgriLife Research scientists in 1945. “Flowering time is important for sorghum no matter what type of sorghum is grown,” Murphy says. “In the case of bioenergy sorghum, you want to delay flowering because the more you delay flowering, the more biomass sorghum will accumulate.” She added that the new discovery allows sorghum breeders to determine at a plant’s flowering genotype at a very early stage, before the plant matures.

It will take time before high-biomass sorghum is grown widely, says John Mullet, AgriLife Research biochemist. For one thing, there’s not a big demand right now as it will take time for full-scale build out of the U.S. biorefinery industry. In the meantime, researchers will continue to develop hybrids, much as new corn hybrids have increased yields over the years. “Breeding and development are likely to make steady improvements in crop design over at least the next 10 years,” he says. 

—Holly Jessen