The project started in 1980, when Dr. Tom Archer, Texas Agricultural
Experiment Station research
entomologist and corn breeder, began to identify hybrids with resistance
to mites. For the next 14 years,
Archer focused on identifying and breeding hybrids with resistance
to mites and corn earworm. Since 1995,
Archer and molecular geneticist Dr. Henry Nguyen have selected and
bred drought resistant corn
hybrids and crossed these with their insect resistant lines. Corn breeder
Wenwei Xu joined this team effort
in 1998.
That same year the scientists successfully tested full-season corn hybrids
bred from this germplasm. These
hybrids produced 95 bushels per acre from only 4 inches of rain and
12 inches of supplemental irrigation (5
inches of which was applied prior to tassel), and show good resistance
to yield-reducing pests such as mites
and corn earworms. In contrast, a drought-resistant commercial hybrid
(Pioneer 3223) produced 53 bushels
under the same conditions.
“We are making good progress breeding less thirsty, drought-resistant
food and field corns, using corn lines
bred here for insect resistance,” Xu said. “We know that under drought
conditions, drought-tolerant plants
employ several mechanisms – one of which is short anthesis-silking
interval (ASI). Our work centers on
transferring the genes responsible for short ASI from tropical germplasm
into temperate corn lines bred to
perform and yield well under West Texas’ sometimes harsh growing conditions.
“The idea is that corn lines bred to survive and thrive in West Texas
will be tough enough to thrive
anywhere else in the world.”
Selecting and breeding hybrids for insect resistance and drought tolerance
is only part of the equation,
however. The scientists also are identifying, selecting and breeding
corn hybrids for the “stay green” quality
and for heat tolerance to increase stress resistance, Archer said.
Working closely with Drs. Archer, Nguyen and Xu at Lubbock is Dr. Javier
Betran, Texas A&M
University corn breeder based in College Station. Xu and Nguyen carry
out their work under joint
appointments from Texas A&M University and Texas Tech University.
The process of transferring superior genes from tropical germplasm into
existing temperate corn lines is
called “introgression,” Xu noted. It isn’t easy work.
Crossing tropical and temperate corn germplasm requires hand pollination
in the field and greenhouse.
Fortunately, the Lubbock center’s greenhouses and winter nurseries
in Florida enable the researchers to
produce two generations of corn lines each year. Crosses of tropical
and temperate corn, and their
offspring, are then evaluated for drought and insect resistance. Only
the best of these plants are selected as
breeding candidates.
“Investigating the physiological and genetic mechanisms of corn’s drought
and heat resistance can be pretty
slow work. To speed it up, we are using molecular marker-assisted selection
in the breeding process. By
using molecular mapping and molecular markers, we can do a better job
of identifying and introducing
genes that transfer drought resistance traits.”
The corn breeding project is partially funded by a corn producer checkoff administered by the Texas Corn Producers Board. The High Plains Underground Water Conservation District also contributed support funds, and some of the work falls under the United States Department of Agriculture’s Germplasm Enhancement of Maize (GEM) project.
GEM is a cooperative effort of USDA’s Agricultural Research Service
(ARS), land-grant universities and
ag industry. It allows scientists to share access to new public and
private corn germplasms.
“By diversifying the pool of corn germplasm available to public and
private breeders, we can accelerate the
process of developing corn hybrids with multiple stress resistance,”
Xu concluded. “We are still three to
five years away from releasing hybrids based on the lines we are developing.
But they are a start in
fulfilling the farmer’s need for productive, early-season corns that
require less water and withstand insect
damage.”