What started as research to control spider mite damage more than 20 years ago has developed into much needed drought-tolerant corn lines for rain-strapped growers.

Texas corn breeders have released new drought-tolerant lines developed in nature's ultimate laboratory — back-to-back-to-back summers with extraordinary heat and dust-filled rain gauges.

Even though the corn lines yielded barely 50 bu/acre, they did so under no irrigation and less than 10" of rain during the five-week period before and after flowering.

That tells Texas A&M University geneticist Wenwei Xu that when bred to proven commercial lines, the germplasm could provide growers with a better defense against drought and limited irrigation water supplies.

“We know that under drought conditions, drought-tolerant plants employ several mechanisms, such as short anthesis-silking interval (ASI) and strong root systems,” says Xu. “Our work centers on transferring the genes responsible for traits from tropical (Mexican-grown) germplasm into temperate corn lines bred to perform and yield well under sometimes harsh growing conditions in West Texas and the High Plains.

“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,” he says.

Mites have always been a perennial problem for High Plains corn producers. Hot, dry weather after silking poses the biggest threats of damaging mite infestations.

Entomologist Tom Archer started looking for solutions through corn genetics in 1980. His Lubbock, TX, research was partially funded by the Texas Corn Producers Board, as is much of the current Texas A&M corn research.

His findings evolved into germplasm that could provide mite resistance by breeding more stress-tolerant corn. In the mid-'90s, the experimental lines produced 95-bu corn on about 4" of rain and 12" of irrigation, 5" of which were applied before tasseling.

Those studies were expanded after extended dry weather in the late 1990s and into the new century. Breeding programs by Xu and others are aimed at offsetting corn losses.

Experimental lines showing the most promise are medium- to full-season, with 110- to 115-day maturities. “We're also selecting lines for short-season production in limited water areas,” says Xu. “These lines will yield about 25% fewer bushels, but on only 15" of total water. That compares to fully-irrigated corn that receives about 25" of water on the semi-arid High Plains.”

These lines are being made available to commercial seed companies to incorporate into their breeding programs. Xu says corn producers could see commercial hybrids containing these traits in three to five years.

Terry Kastens, crop production economist at Kansas State University, believes use of these types of corn hybrids will expand. “The Corn Belt keeps moving farther west,” says Kastens, a dryland corn producer in western Kansas.

He feels the drought-tolerant lines should be more popular with growers whose water sources are dwindling. “Before, when irrigation water was limited, growers planted fewer acres,” he says. “Today, we're seeing more movement toward different hybrids that can handle more stress.”

However, he believes growers with sufficient irrigation water will continue to push for maximum production.

“Until it becomes painful with continued high energy costs, farmers won't see an incentive to change,” he says. “Many will still apply 20" or more irrigation water to produce 200-bu-plus corn.”