Physiology Breeding for Drought Tolerance at University of Idaho Wheat Breeding and Genetics Program.

Water stress is one of the most destructive abiotic stresses that limit wheat production and is difficult to address through genetic improvement. The genetic mechanisms controlling drought related traits are ambiguous and poorly understood. The University of Idaho Wheat Breeding and Genetics Programs have deployed an integrated approach combining extensive field evaluation and QTL identification to address such production concerns. Adapted spring wheat cultivars and advanced lines have been evaluated in a controlled water environment in a drip nursery. Breeding and mapping populations have been evaluated in a nursery applied water stress after flowering (terminate drought stress). Grain yield and four physiological traits (flag leaf senescence, carbon isotope discrimination, canopy temperature, and chlorophyll content) have been evaluated to identify drought tolerant wheat genotypes and to identify QTL associated with the four traits that can be used to select yield response under drought stress. At present, we have developed protocols to evaluate the four traits in the field nurseries and identified indexes of the four traits to evaluate yield response under drought. As this progressing, we identified seven spring wheat cultivars and lines having tolerance to water stress, and QTL and markers associated with grain yield and the four physiological traits. The knowledge developed from our program would accelerate breeding for drought tolerance in wheat and other cereal crops.