2007 Annual Report 1a.Objectives (from AD-416) The objectives of this research are (1) to conduct multi-location field trials to expedite the commercialization of new multiple stress tolerant corn hybrids that are not currently available in Texas and other Southern states, and (2) develop extension publications for using these hybrids. 1b.Approach (from AD-416) Corn hybrids developed by the Texas Agricultural Experiment Sation and other widely grown hybrids will be grown at seven locations in Texas and Mississippi under different degrees of drought stress. At some locations the hybrids will be inoculated with Aspergillus flavus. Data will be recorded on flowering date, plant height, lodging, and other agronomic traits. Mature ears will be hand harvested and rated for ear molds and insect damage. Grain will be analyzed for aflatoxin contamination. The proposed research will help to identify multiple stress resistant corn and provide the germplasm and information needed by the seed industry to develop and commercialize hybrids with resistance to aflatoxin contamination. 3.Progress Report This report serves to document research conducted under a Specific Cooperative Agreement between ARS and Texas A&M University. Additional details of research can be found in the report for the in-house project 6406-21000-009-00D, "Enhancing Corn with Resistance to Aflatoxin Contamination and Insect Damage." The corn breeding program at Texad Agricultural Experiment Station (TAES)-Lubbock Center is developing multiple-stress tolerant corn. The process to reduce aflatoxin contamination involves four steps: 1. Evaluate diverse germplasm for stress tolerance (drought, heat, corn earworm, and grain mold) and agronomic traits. 2. Develop stress-tolerant lines from temperate x tropical populations. 3. Evaluate testcrosses between advanced TAES lines and public or private tester lines for yield and stress tolerance. 4. Choose best testcrosses with acceptable yields and good abiotic and biotic stress tolerance, and test them for aflatoxin and agronomic traits in diverse environments. In 2005 and 2006, 21 experimental hybrids and commercial hybrid checks were grown in replicated trials at Lubbock, Halfway, Dumas, Corpus Christi, and Beeville in Texas and at Mississippi State, MS. The Lubbock and Halfway locations had optimum and limited irrigation treatments. The experimental hybrids were developed by the Texas Agricultural Experiment Station corn breeding program at Lubbock. They were chosen for improved drought tolerance and earworm resistance. In Lubbock and Halfway, plants were inoculated one week after silk emergence by injecting an Aspergillus flavus spore suspension into the silk channel. In Corpus Christi and Beeville, corn kernels colonized by A. flavus were distributed between rows when the earliest hybrid was at the mid-silk stage to provide increased and uniform aerial dissemination of conidia. Plants at Mississippi State were sprayed with a spore suspension weekly for five weeks beginning when the earliest hybrids reached mid-silk. Aflatoxin was low at Lubbock and Halfway. Aflatoxin contamination was high and significantly different among hybrids at Corpus Christi, Beeville, and Mississippi State. At those locations, the six Texas Agricultural Experiment Station hybrids, especially S2B73BC × NC300 and S1W × CML343, exhibited consistently low levels of aflatoxin accumulation. Grain yields were comparable to commercial check hybrids. These results indicate that the new hybrids such as S2B73BC × NC300 have comparable yield yet significantly lower aflatoxin contamination than commercial hybrids. The results of the research will help the seed industry to commercialize this new germplasm and lead to the marketing of corn hybrids with multiple stress tolerance and adaptation to Texas and other southern states. Research progress is monitored through semi-annual written progress reports, phone calls, exchanges of experimental data, and a formal presentation of research results at the annual Aflatoxin/Fumonisin Elimination Workshop.