Maize (Zea mays L.) is grown in a wide range of environments and altitudes
worldwide. Maize has transitioned from open pollinated varieties to single cross hybrids
over the last century. While maize production and genetic gain has increased, genetic
diversity among U.S. maize hybrids has narrowed. Problems, such as insect pressure,
diseases, and mycotoxins, present obstacles for breeders. One approach is to use exotic
germplasm in breeding programs to provide useful, novel alleles for productivity, grain
quality, and disease resistance. Little exotic germplasm has been used, because of lack
of agronomic adaptation and problems with lodging, earliness, and tall plants in more
temperate areas. Using exotic elite materials and evaluating them in targeted regions
might increase success. Objectives of this research were: to characterize and evaluate
agronomic adaptation and performance of Argentine commercial hybrids in the U.S., to
evaluate semi-exotic testcrosses developed from semi adapted 100% tropical lines and
elite U.S. inbred LH195, and to estimate response to aflatoxin contamination of
Argentine hybrids and semi-exotic testcrosses under inoculation with Aspergillus flavus. Agronomic data was collected during 2004 in eleven Texas environments for
Argentine hybrids, and eight Texas environments for semi-exotic testcrosses. Response
to aflatoxin was measured in three southern Texas environments. U.S. commercial
hybrids were used as checks. Significant differences among hybrids were observed for
most environments and traits. In general, Argentine hybrids yielded lower, had lower
1000 kernel weights, and greater test weights than U.S. hybrids. Hybrids AX889,
AX882MG, and AX890MG were competitive with U.S. hybrids for grain yield and were
stable across environments. Semi-exotic testcrosses had similar lodging and grain
moisture percentages, heavier test weights and competitive grain yields compared with
U.S. hybrids. Hybrid TX-LAMA2002-9-2-B/lH195 had the highest overall grain yield
mean for semi-exotic testcrosses and yielded better than two U.S. hybrids. Argentine
hybrids had lower aflatoxin concentration than U.S. hybrids; several hybrids had less
than 50 ng g-1 aflatoxin. Semi-exotic testcrosses had reduced aflatoxin compared to U.S.
hybrids, with several hybrids under 35 ng g-1. These elite, exotic materials show promise
for breeding programs, with competitiveness for grain yield, kernel traits, and reduced
aflatoxin levels.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/2625 |
| Date | 01 November 2005 |
| Creators | Ochs, Brett Allen |
| Contributors | Betran, F. Javier |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 6219334 bytes, electronic, application/pdf, born digital |
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