Grain sorghum producers will soon be reaping benefits from new hybrids with improved early-season cold tolerance.

“Genes for this trait are being incorporated into superior breeding lines, which in turn will be used to develop improved commercial hybrids,” says Cleve Franks, sorghum geneticist with the USDA Agricultural Research Service at Lubbock.

In searching the world sorghum collection for lines with superior cold tolerance, Franks tested seed from both foreign and domestic sources for germination and seedling vigor at less than optimal temperatures. “We found that seed from certain exotic lines from China germinated well at temperatures as low as 50 degrees, and the resulting seedlings grew acceptably well at that temperature.

“Unfortunately, plants in these Chinese lines were very tall at maturity with very open heads and rather low yields. But by careful breeding and selection, we have been able to transfer genes for the cold-tolerance trait into sorghum lines more adapted to U.S. production systems, having much shorter plants with tighter heads and more seed,” Franks said.

Commercial breeders can use these lines to produce new hybrids with greater cold tolerance. “Since seed from these improved hybrids will germinate and produce healthy seedlings at sub-normal temperatures, we hope producers who plant them will see higher grain yields, more biomass, and higher economic returns,” Franks said.

Reasons to expect higher yields of grain and biomass from early plantings include more effective utilization of spring and early summer rainfall, fewer problems with sorghum-damaging insects, and potential for a longer overall growing season, as with corn.

“Also, the plants will flower and mature in a cooler, more favorable part of the growing season, and there will be a lower potential for bird damage because the grain probably will be harvested before significant numbers of migratory birds arrive,” Franks said.

Franks primarily uses conventional breeding methods to develop the cold-tolerant lines. But he also relies on the expertise of colleague Gloria Burow, Agricultural Research Service molecular geneticist, to identify molecular markers for genes responsible for the trait. “Dr. Burow's application of this technique will expedite incorporation of cold-tolerance genes into improved lines,” Franks said.

During selection and evaluation, Franks tested the breeding lines in seven or more locations to assess potential of parental material for development of new hybrids. Locations extended from Halfway, Texas, to Puerta Vallarta, Mexico.

Lines in these tests that meet acceptable criteria are made available to seed companies and other researchers for further testing. Commercial breeders (and others) are free to utilize them in developing improved hybrids. “Ultimately, producers will be the ones who really benefit from our program, and that is as it should be,” Franks said.

Franks works closely with Texas Tech University, Texas A&M University, and commercial sorghum companies in the development and testing of these superior breeding lines.