AgriLife Research study aimed at reducing drought-stress losses to wheat

AMARILLO – Texas AgriLife Research scientists are trying to make the best of an “extreme” situation. Drought conditions crippled wheat crops the past year; but drought is not new, it is expected to continue and needs to be dealt with, according to the group.

Known to be more drought resistant, the TAM 112 wheat variety on the left exhibits stronger vigor and produced more and bigger heads and more seeds per head in comparison to TAM 110 on the right in this research trial studied by Dr. Qingwu Xue, Texas AgriLife Research crop stress physiologist in Amarillo. (Texas AgriLife Research photo by Dr. Qingwu Xue)

“Texas AgriLife Research is building a very strong team to study the drought tolerance in wheat in the Texas Panhandle, which is one of the best environments in the world to work on drought,” according to Dr. Jackie Rudd, AgriLife Research wheat breeder.

During 2011, drought stress resulted in the loss of about 240 million bushels of winter wheat in the Southern Great Plains. Texas wheat production was down 80 million bushels from the 2010 crop, Rudd said, which is “close to a $500 million hit on the Texas economy at today’s wheat prices.”

The team will look at different angles of drought stress in wheat with different expertise, but all with the same objective in mind: develop wheat varieties for the variable and unpredictable High Plains’ environment, Rudd said.

Wheat is the second most important cereal crop in the U.S. and winter wheat, planted on 70 percent of the cultivated wheat area, often suffers yield reductions due to periodic drought, he said.

Rudd is joining forces with Dr. Qingwu Xue, AgriLife Research crop stress physiologist;
Dr. Shuyu Liu, AgriLife Research small grains geneticist; and Dr. Srirama Krishna Reddy, a postdoctoral research associate, to take drought studies from the field to genetic laboratories and back to producers with more drought-tolerant wheat varieties that can reduce those losses.

“We chose three wheat varieties that are all among the top yielding under irrigation but they differ in their yield response to drought,” Rudd said. “The next step is to determine what is going on inside the plant and use this understanding to move to the next level.”

The three AgriLife Research-produced wheat varieties, TAM 111, TAM 112 and TAM 304, are widely planted – 3.25 million acres in 2011- in the Southern Great Plains, he said. While it is known that each has a different response to water stress, the physiological and molecular basis of their adaptation is unknown.

TAM 112 is the best when the drought is season-long like this past year, Rudd said. TAM 111 can take intermittent dry spells very well but needs rain from time to time. TAM 304 yields great when fully irrigated, but is usually not in the top ranks in dry years.

The team has already learned a lot by collecting data during two contrasting years of rainfall. 2010 was a good year for wheat yield and 2011 was one of the driest years on record, he said.

“Initially, we propose to use physiological measurements and yield parameters to evaluate the impact of specific drought-stress treatments on the phenotype and physiology of the plants in controlled greenhouse and field conditions,” Xue said.

“We will then employ a systems biology approach to elucidate the drought tolerance mechanisms of the above mentioned varieties,” Krishna Reddy said. “Recent advances in genetics and basic biology have given us tools that will complement the traditional breeding approach.”

“Understanding the mechanisms of drought tolerance will enable us to design more effective molecular markers to be used in screening breeding populations for wheat improvement,” Liu said.

The results will be validated under field conditions with a wide range of wheat genotypes. Then wheat breeders can apply the molecular markers to screen for targeted drought-tolerance genes in breeding programs, he said.

Rudd said the knowledge generated will help to accelerate variety development in the U.S. and in other similar environments throughout the world, and ultimately result in the release of drought-stress tolerant and high-yielding wheat varieties that benefit producers.

“Improved genetics cannot replace timely rains, but we have made significant improvements in drought tolerance through traditional plant breeding and further improvements are likely in the future,” Rudd said. “Preliminary projects supported by the Texas Wheat Producers and the federallyfunded Ogallala Aquifer Program have given us valuable insight into our past accomplishments and a clear direction for future research.”



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