Phenotypic Screening and Breeding of Drought Tolerant Corn.

Water is a major limiting factor for corn production.  Superior hybrids with improved stress tolerance are a key to reduce drought’s effect.  Drought tolerance is a complex trait.  Accurate screening for drought tolerance depends on the timing, intensity and duration of drought stress.  Plants respond variably to different types of drought stress.  We have developed a protocol for screening a large number of lines and hybrids for drought and heat tolerance in the field by taking advantage of low rainfall in West Texas and excellent subsurface drip irrigation systems. Plant stress rating, stay green, and ear traits are important characters associated with drought response.  We introgress native stress tolerance genes from tropical and sub-tropical germplasm by crossing them with temperate adapted lines and making selections under controlled drought stress conditions.  A useful source for stress tolerance is the germplasm from the USDA GEM project.  Drought-tolerant hybrids have a stronger root system, higher hydraulic lift capacity, and recover better when drought stress is relieved.  The new stress tolerant corn can save water, reduce yield loss and aflatoxin contamination.