Grain Yield, Drought Tolerance, and Corn Earworm Resistance of GEM Breeding Crosses Wenwei Xu Agricultural Research and Extension Center Texas A&M University Lubbock, TX 79403 Objectives To characterize the yield potential, drought tolerance, and corn earworm resistance of 71 GEM breeding crosses; To select the best germplasm for developing drought tolerant and CEW resistant inbred lines. Materials and Methods 71 GEM breeding crosses: 25-50% tropical germplasm. Checks: B73xMo17, Pioneer hybrids 34K77 and 3223. Three water treatments: Well-irrigation: 16.4 acre-inch irrigation water. Severe drought stress 1: 5.2 acre-inch irrigation water. Severe drought stress 2: 7.0 acre-inch irrigation water. ANTIGO03:N12 GOQUEEN:N16 Nine GEM Breeding Crosses with Above Average CEW Resistance as measured by CEW Ear Penetration (cm) Crosses BG070404:D27 BR51501:N11a CUBA84:D27 BR51675:D27 ANTIG01:N16 CEW 4.0 4.6 5.0 5.2 5.4 Crosses DK888:N11a ANTIG03:N12 DKXL380:N11a 5.1 DK212T:N11a CEW 4.2 4.8 5.2 Top 15 Breeding Crosses ANTIG03:N12 AR16026:N12 BG070404:D27 CUBA84:D27 ANTIG03:N1216 PRICGP3:N1211c BR51403:N16 GUAD05:N06 UR11002:N0308b ANTIG01:N16 PRICGP3:N1218 CUBA164:D27 CH05015:N1204 BR51501:N11a BR51675:N0620 ANTIG03:N12 yielded well under irrigated and drought stressed conditions, and had good CEW resistance, low grain mold, good stay green trait, upright leaves, and good husk coverage. Control of Aflatoxin by Improving Drought Tolerance in Corn Wenwei Xu1 and Gary Odvody2 1. Texas A&M University Agricultural Research and Extension Center, Route 3, Box 219, Lubbock, Texas 79403 2. Texas A&M University Agricultural Research and Extension Center, 10345 Agnes Street, Corpus Christi, Texas 78406 Drought and heat tolerant corn have less grain molds under drought stress. We believe that the primary reason for high aflatoxin in southern environments is the lack of commercial corn hybrids specifically adapted to this region. This study tested our hypothesis that genetic improvement of stress tolerance can reduce the aflatoxin risk in Southern environments. Lubbock College Station Corpus Christi Kernels colonized by a high aflatoxin-producing isolate of A. flavus (NRRL3375) were distributed between rows of each plot when the first hybrids were at mid-milk stage to provided uniform aerial inoculum for infection. Aflatoxin level in ppb (Mean SD) of the experimental hybrid CML343xTx202 and two check hybrids under inoculated field at Corpus Christi in 2000, 2001 and 2002. Entry CML343xTx202 P31B13 2000 2001 2002 Aflatoxin 12027 20783 20781 Log (afl) 4.80.2 5.30.4 5.300.4 Aflatoxin 703185 25331168 660252 Log (afl) 6.50.3 7.80.5 6.40.4 Aflatoxin 6027 17721 13010 Log (afl) 4.00.4 5.20.1 4.90.1 Aflatoxin 398 1276 849 Log (afl) 5.8 6.9 6.5 Aflatoxin 60-767 177-2533 130-1303 CV% for Aflatoxin 38.6 55.5 41.6 LSD 0.05 for Log(afl) 0.6 0.8 0.7 DK XL269 Test Mean Test Range Ears of CML343xTx202 at Corpus Christi in 2000. Conclusions CML343xTX202, an experimental hybrid developed by TAES-Lubbock corn breeding program, had 69% to 92% lower aflatoxin content than the check Pioneer hybrid 31B13 under A. flavus-inoculated field conditions over three years. Drought tolerance, good husk coverage, and low insect injury on ears may contribute to the low aflatoxin in CML343xTx202. Results indicate that breeding for drought tolerance and earworm resistance is a promising approach to reduce aflatoxin contamination in corn grown in Southern environments.