Wheat is an important grain and forage crop for Texas farmers and livestock producers. Texas Agricultural Experiment Station scientists regularly evaluate new lines of this crop, seeking ways to improve its yield potential and adaptability to different growing conditions.

What if scientists could assess forage or grain potential by examining the structure and form of plants, by simply looking at unique physiological traits?

"If we can identify morphological and physiological traits that correlate with better grain or forage production, we could streamline the wheat breeding and selection process," said Dr. Dariusz Malinowski, Experiment Station assistant professor-forages here.

"That is the idea behind a research project we started here in 2002," he said. "We are looking for traits that are good indicators of grain and forage yield potential."

Malinowski is conducting this research with Dr. Jackie Rudd, Experiment Station wheat breeder at Amarillo, and Dr. William E. Pinchak, Experiment Station ruminant nutritionist here. They began by examining 80 wheats in the Texas elite wheat and the Texas uniform variety collections. Wheats in both collections are evaluated for adaptability to the wide range of growing conditions that exist in Texas and the Southwest.

"We categorized them into groups, such as high-and-low grain or forage yield, disease resistance, and tillering," Malinowski said. "We narrowed the list of wheats with 'good' and 'bad' traits down to 28. Then we planted these in large irrigated and dryland plots for two years to evaluate their performance under grazing and artificial defoliation, or clipping."

The plots were planted around Sept. 15 in 2003 and 2004. Drought delayed grazing trials in 2003, but above-average rainfall in 2004 boosted stand establishment and enabled the grazing trials to begin in November.
"We saw some interesting differences among these wheats in our dryland and irrigated trials in both 2003 and 2004," Malinowski said. "Early forage production was positively correlated with tiller number, leaf length and leaf area.

"The positive correlations based on leaf characteristics were most evident in our dryland plots. We also saw a negative correlation between specific leaf weight and early forage production in both years, in dryland and irrigated trials."

In other words, the best forage yields in their trials came from wheats that produced longer, thinner leaves and more tillers. These wheats also produced leaves with a lower specific weight – they grew lighter, longer, thinner leaves, and more of them.

"When growing conditions are favorable, this is just what you would expect of fast-growing grasses," Malinowski said. "These traits may be useful to breeders because they are easily distinguishable in the field."

The scientists also learned that weather may affect the chemistry of growing wheat plants and the health of grazing cattle.

"We think that phenolic compounds in the plant may play a role in reducing bloat in cattle grazing wheat," Malinowski said. "Phenolic compounds protect plants from a range of oxidants, including ultraviolet rays. They are, in effect, a natural sunscreen produced by the plant in the presence of abundant sunshine.

"They also buffer digestion and have antimicrobial properties in the stomach of cattle. They may allow the animal to digest the forage without producing excess gas that leads to bloat."

Because bloat often occurs when the weather is cloudy and cold, the scientists theorize that breeding wheats that maintain high phenol content under these conditions could help reduce bloat and its often-fatal impact on grazing cattle.

"We placed cages in our wheat plots and shaded the plants under the cages to regulate the amount of sunlight the plants received," Malinowski said. "We found that the shaded plants had lower levels of phenolic compounds, especially when the temperature was cooler or cold."

The scientists plan to continue the research and add new wheats to their trials. Their future work will also seek to confirm the theory that wheat's natural sunscreen helps grazing cattle remain healthy when the weather turns cloudy and cool.

Their three-year study was funded by contributions from the Texas Wheat Producers Board.