AMARILLO – With much of Texas in the grip of mild to severe drought – wheat growers are fielding some of this season's hardest hits.
But even now, Dr. Mark Lazar, a wheat breeder with the Texas Agricultural Experiment Station, is looking forward to reporting some positive outcomes involving his drought resistance research during the upcoming Ag Day 2000 scheduled June 1 at Bushland.
Despite wheat's poor showing in some fields, Lazar is seeing changes in the molecular structure of plants as they respond to extremely dry conditions. He says any variation offers potential keys to fortify drought resistance.
Very low or totally absent spring rains over the past six weeks have forced yields way down. The greatest crop demand for water starts as plants approach and pass the flowering stage, Lazar said.
"This happened right in the middle of our droughty weather," Lazar noted.
Dry conditions severely reduced dryland yields, but such extremes are aiding Lazar's studies on genetic differences in yield under water stress. Right now, he and Dr. Maria Balota, a visiting scientist from Romania, are evaluating several varieties across all breeding nurseries for a range of green leaf retention capabilities while plants are under stress. This "stay green" trait is similar to the one found in sorghum.
Balota uses infrared or heat-detecting sensors to look for a relationship between temperature in the crop canopy, reflecting the rate of water flowing through a plant, and its ability to withstand drought. This principle could be used to develop a screening tool to evaluate breeding lines in the future. She also thinks other radiation wavelengths might be useful with such detectors.
"What we're seeing in wheat isn't as dramatic as in sorghum," he said. "But, repeatable differences in the ability to retain green leaf color do exist in the breeding lines."
The trick will be to combine strong green leaf retention with excellent yield potential and other important characteristics, since the current drought isn't likely to happen every year. Finding ways to correctly estimate green leaf retention without a strong drought also drives his research.
Over the long term, where small physiological changes can be combined to produce big results – Lazar's team will be using several closely-related wheat lines to look for differences in yield response under different water availability.
"In controlled conditions, these lines appear to have two traits that differ," he explained. One involves the capacity for leaves to remain unwilted under water stress. The second deals with the total length of the root systems. He hopes to confirm the differences in the field with individual plants derived from a cross of two closely-related lines.
"If we can accurately identify differences in these traits in single plants, then developing DNA markers for each trait and using them as selection tools is possible, too," Lazar said.