Location: Corn Host Plant Resistance Research2009 Annual Report
1a. Objectives (from AD-416)
The objectives of this proposal are: (1) to evaluate aflatoxin, yield, and agronomic traits of the new high yielding TAES experimental hybrids for a second year; (2) to conduct large scale strip tests of S2B73BC x BC300 and S1W x CML343 for yield, aflatoxin level, and agronomic traits in TX; (3) to develop and advance new lines toward producing low-aflatoxin corn hybrids; and (4) to participate in SERAT tests. The results from this research will help the seed industry to commercialize the new germplasm and lead to the release of new inbred lines and hybrids with multiple stress tolerance and adaptation to Texas and southern states.
1b. Approach (from AD-416)
Corn hybrids developed by Texas Agricultural Experiment Station and other widely grown hybrids will be grown at 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 mold 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
Contamination of corn grain with aflatoxin, which is produced by the fungus Aspergillus flavus, is a chronic problem in the southern United States. Hot, dry environments stress plants and cause increased aflatoxin production. Producers need corn hybrids with resistance to aflatoxin contamination. Our strategy for breeding corn with resistance to aflatoxin contamination is to improve drought and heat tolerance, improve corn earworm resistance, and stack genes from known sources of resistance such as Mp715 into germplasm adapted to the southern states. Twenty-six experimental and four commercial hybrids were evaluated in 2007 and 2008 at Lubbock, Halfway, Dumas, Corpus Christi, and Beeville in Texas and Mississippi State, MS. The Lubbock and Halfway locations had optimum and limited irrigation treatments. The experimental hybrids were developed by the corn breeding program of Texas AgriLife Research in Lubbock. They were selected for improved drought and corn earworm resistance. In Lubbock and Halfway, plants were inoculated one week after silking by injecting A. flavus conidia into the silk channels of developing ears. At Mississippi State, A. flavus was injected into the side of the ear. In Corpus Christi and Beeville, corn kernels colonized by A. flavus were distributed between rows when the first hybrids reached the mid-silk stage. A later planting date was used at Corpus Christi, Beeville, and Mississippi State to increase the likelihood of drought stress at the later stages of maturity. For all locations, ears were hand harvested and rated for earworm damage and other ear traits. The ears were then shelled, and the grain was analyzed for aflatoxin contamination. Six of the experimental hybrids had significantly lower levels of aflatoxin than the test mean and the four commercial hybrid checks. Fourteen hybrids had 75% lower aflatoxin than the four check hybrids in three environments. Parental lines selected for drought tolerance and from breeding crosses of Mp715 (a line released by USDA-ARS at Mississippi State as a source of resistance to aflatoxin contamination) exhibited desirable levels of resistance to aflatoxin contamination. The hybrids with much lower levels of aflatoxin contamination than the commercial hybrid checks exhibited comparable grain yields and good agronomic characteristics. Preparations for release of these lines are underway. Progress was monitored by e-mail updates, phone calls, conferences, and written progress reports.