Wednesday, November 15, 2006

Introduction and Adaptation of Corn Exotic Lines to Southern U.S.

Rebecca Corn1, Kerry Mayfield2, Cody McKee3, T. Isakeit2, G. Odvody2, and Javier Betran4. (1) Soil and Crop Sciences, Texas A&M, Mail Stop 2474, College Station, TX 77845-2474, (2) Texas A&M, Mail Stop 2474, College Station, TX 77845-2474, (3) Texas A&M Universtiy, Soil & Crop Sci Ms2474, Soil & Crop Sci Ms2474, College Station, TX 77845, United States of America, (4) Texas A&M University, College Station, TX 77843-2474

Tropical maize lines known as LAMA lines were developed to overcome some of the limitations to incorporating exotic germplasm into adapted US hybrids.  The LAMA lines are 100% tropical maize lines that were selected for maturity, grain quality, husk cover, hard endosperm, and standability in two Texas locations to develop tropical lines adapted to Southern US environments.
            The LAMA lines were crossed to two testers, LH195, Stiff Stalk temperate tester, and LH210, a non-stiff stalk type (Holden’s Foundation Seed).   Testcrosses were evaluated for yield and agronomic performance at three locations.  An alpha lattice design was used for field trials.  Two row plots were mechanically harvested and yield, test weight, and grain moisture were taken using harvesting equipment on the combine.  Yield of the LAMA testcrosses was generally lower than the commercial checks.  A set of LAMA lines was then evaluated in five locations.  The LAMA testcrosses had the same mean test weight as the commercial checks, but the mean grain moisture percentage of the LAMA lines was 2 percent higher than the checks.
            A subset of the LAMA testcrosses was evaluated for response to aflatoxin under inoculation with Aspergillus flavus using silk channel (College Station, Weslaco) or colonized kernel (Corpus Christi) inoculations.  Single row plots in an alpha lattice design were used at all three locations.  Vicam Aflatest® antibody columns were used for aflatoxin quantification.  The LAMA testcrosses were generally less susceptible to aflatoxin than the commercial checks.  LAMA2002-12-1-B/LH195 had less than 100 ppb aflatoxin at Weslaco.  LAMA2002-10-1-B/LH195 was the only hybrid to have less than 200 ppb aflatoxin across locations.  Two hybrids, LAMA2002-1-5-B/LH210 and LAMA2002-25-5-B/LH195, had less than 30 ppb aflatoxin in the College Station location.
            These exotic lines adapted to the Southern U.S. had lower grain yields than commercial checks, but they may harbor resistance factors for aflatoxin.