Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 9/1/2005
Publication Date: 10/23/2005
Citation: Xu, W., Zhang, J., Odvody, G., Williams, W.P. 2005. Corn hybrids with exotic germplasm and low-aflatoxin [abstract]. In: Proceedings of the 2005 Multicrop Aflatoxin/Fumonisin Elimination & Fungal Genomics Workshop, October 23-27, 2005, Raleigh, North Carolina. p. 74. Interpretive Summary:
Technical Abstract: Aflatoxin contamination of corn by A. flavus is a chronic problem in the southern United States. Currently, aflatoxin resistant commercial hybrids are not available. Lack of adaptation to the hot and dry southern environments may be a major reason for the high incidence of aflatoxins in this region. A hot and dry environment not only favors aflatoxin production, but also stresses the plants, which leads to the break down of plant resistance to diseases and in turn to an increase in aflatoxin production. The corn breeding program at the Texas Agricultural Experiment Station (TAES) at Lubbock has been developing drought tolerant corn hybrids by introgressing tropical corn germplasm. We have observed that under drought conditions, drought tolerant corn hybrids produced a higher yield and had much less grain mold than susceptible hybrids. The objective of this study was to determine if genetic improvement of abiotic stress tolerance and corn earworm resistance can reduce the aflatoxin risk in this region. Ten experimental hybrids developed by the corn-breeding program of the Texas Agricultural Experiment Station (TAES) in Lubbock, TX and commercial checks (Pioneer hybrids 34K77 and 31B13, Garst 8285, Triumph 1416, and DK XL269) were grown under replicated trials in Lubbock, Halfway, Corpus Christi, and Beeville in Texas and Mississippi State, MS in 2003 and 2004. In Lubbock and Halfway, plants were inoculated one week after silking by injecting A. flavus conidia into silk channels. In Corpus Christi, Beeville, and Mississippi State, corn kernels colonized by A. flavus were distributed between all rows when the first hybrid was at the mid-silking stage to provide the increased and uniform aerial dissemination of conidia. In all cases, the inocolum was from a high aflatoxin-producing A. flavus strain (NRRL3357). A limited late planting date was used in Corpus Christi, Beeville and Mississippi State to encourage severe drought stress at later stages of maturity. Two-year results showed that S1W x CML343 and S2B73 x NC300 had significantly lower aflatoxin than the control hybrids. Hybrid B110 x SGP3 had high yielding and high aflatoxin in most environments in two years. In 2003, the aflatoxin level in S1W x CML343, S2B73 x NC300 and P31B13 was 49, 31, and 161 ppb, respectively, at Corpus Christi, TX. The aflatoxin of the Mississippi State test in 2003 was generally low and not significant among the entries. The results in 2004 were in general consistent with the results in 2003. In 2004, the aflatoxin levels in S1W x CML343, S2B73 x NC300, and P31B13 (CK) was, respectively, 5.3, 16.7, and 70.0 ppb at Corpus Christi; 10.1, 9.4, 5.8 and 33.3 ppb at Mississippi State. In 2004, Lubbock had the rainfall and temperatures favorable for corn growth and development. The aflatoxin levels under well-watered and drought stressed test in Lubbock were similar, although the average grain yield of the 14 entries declined from 184 bu/a in well-watered condition to 126 bu/a in drought stressed condition. The aflatoxin levels in S1W x CML343, S2B73 x NC300, and P31B13 was 90.0, 30.5, and 260.0 ppb under well-irrigated conditions (mean of 14 hybrids as 134.8 ppb), while under drought conditions were 93.5, 33.5, and 240 ppb (mean of 14 hybrids as 120.5 ppb).