Progress 10/01/99 to 09/30/05
Outputs
Inbred line DE6, derived from a Germplasm Enhancement of Maize (GEM) breeding cross(Brazilian tropical maize single-cross Dekalb hybrid DKXL212 crossed to elite non-Stiff Stalk temperate inbred N11a), was released in March 2005 based on its potential as a high protein source of germplasm in maize improvement programs. DE6 has a protein level ranging from 16.1 to 19.4 percent (dry matter basis) compared to 12.0 to 12.9 percent for B73Ht. Several GEM recycled lines had improved grain yields and lower grain moisture than the released GEM inbred lines. Anthracnose stalk rot (ASR) evaluations of hybrids involving DE811 and a near-isogenic DE811ASR resistant line, DE811Rcg1, indicate that hybrids with the Rcg1 gene have less internal discoloration and external stalk rot symptoms. The hybrids with the Rcg1 gene have a lower percent of plants with top-dieback symptoms compared to the near-isogenic hybrids. The near-isogenic hybrids without the Rcg1 gene have weaker stalks and
the pith tissue was completely destroyed. The Rcg1 gene reduced ASR disease development in all the hybrid genetic backgrounds evaluated and should be a useful genetic source of resistance to Colletotrichum graminicola.
Impacts
Inbreds developed from the USDA-ARS Germplasm Enhancement of Maize (GEM) project should be useful and novel sources for improving value added traits such as protein, oil, and starch, agronomic traits, and resistance to pests in both dent and sweet corn breeding programs. The Rcg1 gene should be a useful genetic source of resistance to Colletotrichum graminicola.
Publications
- Hawk, J.A., Weldekidan, T., and Frey, T.J. 2005. Experience using GEM germplasm in a public breeding program. 60th NE Corn Improvement Conference (NEC-29), Feb. 10-11, 2005. Penn State University, University Park, PA.
- Hawk, J.A., T. Weldekidan 2005. Registration of DE3, DE4, and DE5 Parental Inbred Lines of Maize. Crop Sci. 45:2669-2670.
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Progress 01/01/04 to 12/31/04
Outputs
Inbred line DE4, derived from a Brazilian tropical hybrid DKXL212 crossed to temperate inbred N11a, has excellent gray leaf spot resistance both per se and in hybrid combinations. DE4 recycled lines had improved grain yields and lower grain moisture than DE4 and will be further evaluated in 2005. Several new lines derived from the USDA Germplasm Enhancement of Maize (GEM) program had good yield and agronomic performance in 2004. These lines will be further evaluated on additional testers and environments. An experimental inbred line derived from a Brazilian tropical hybrid DKXL212 crossed to temperate inbred N11a has higher percent protein content compared to B73Ht (16.2 vs. 12.2%). A Stewart's bacterial wilt vector control study with a combination of insecticide/fungicide seed treatments showed significantly lower flea beetle damage and Stewart's bacterial wilt incidence than the untreated control.
Impacts
Inbreds developed from a recurrent selection program initiated with BSSS(R)C11 from Iowa State University and from a GEM breeding cross should be useful and novel sources for improving resistance to pests in both dent and sweet corn breeding programs. Vector control with insecticide seed treatments may be useful for reducing the incidence of Stewart's bacterial wilt in highly susceptible hybrids.
Publications
- Pataky, J.K, Michener, P.M. Freeman, N.D., Whalen, J.M., Hawk, J.A., Weldekidan, T., and Teyker, R.H. 2004. Rates of seed treatment insecticides and control of Stewart's wilt in sweet corn. Plant Dis. (In press)
- Willmot, D., B.E. Hibbard, L.L. Darrah, L.M. Pollak, K. Montgomery, R. Pratt, C. A. Abel, J. Hawk, T. Weldekidan, and J. Foster. 2004. Effect of environment on resistance to the European corn borer (Lepidoptera: Crambidae) in maize. J. Econ. Entomol. 97(5): 1745-1751.
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Progress 01/01/03 to 12/31/03
Outputs
Six Delaware inbred lines were screened for European corn borer (ECB) resistance at Newark, DE. Among the lines tested, DE5 showed high resistance to leaf feeding and intermediate resistance for sheath-collar resistance. DE3 and DE4 rated intermediate for sheath-collar resistance. DE5 may be useful as a germplasm source for improving ECB resistance in both dent and sweet corn breeding programs. A Stewart's bacterial wilt control study involving two susceptible sweet corn hybrids (Legacy and Jubilee) and four insecticide seed treatments (Gaucho and Poncho at one rate, LO263-A1 and Cruiser at three rates) was conducted at Newark, DE. The four insecticides generally gave better flea beetle control compared to the untreated checks. Stewart's bacterial wilt incidence for the first evaluation date at Newark, DE was not significantly different between the seed insecticide treatments and the untreated check for Legacy. However, all seed treatments resulted in lower Stewart's
bacterial wilt incidence for the last two evaluation dates.
Impacts
Inbreds developed from a recurrent selection program initiated with BSSS(R)C11 from Iowa State University and from a Germplasm Enhancement of Maize (GEM) breeding cross should be useful and novel sources for improving resistance to pests in both dent and sweet corn breeding programs. Vector control with insecticide seed treatments may be useful for reducing the incidence of Stewart's bacterial wilt in highly susceptible hybrids.
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
DE(BSSS)C2 inbred lines were evaluated for European corn borer(ECB) resistance at Newark, DE and Cornell University. DE(BSSS)C2 -420-3-2-1-1-1 rated resistant to ECB leaf feeding with an average rating across locations of 1.9 vs. 5.9 for the susceptible inbred (B73) and 3.8 for the resistant check (DE811) on a 1-9 scale with 1 being most resistant. This same line averaged 8.8 cm tunnel length per plant after ECB inoculation at the flowering stage compared to 27 cm for B73 and 9.4 cm for DE811. DE(BSSS)C2 lines were testcrossed to LH185 and evaluated for yield and agronomic performance at three Delaware locations. DE(BSSS)C2-420-3-2-1-1-1 was the top yielding experimental hybrid with an average of 192 bu/A compared to 202 bu/A for the top commercial hybrid of similar maturity. Inbred lines derived from the 50 percent tropical GEM population DKXL212:N11a were evaluated for yield and agronomic performance at Delaware and across the Mid-West (18 locations, 25 reps). Three
lines were identified with yields not significantly different from the commercial check means but with significantly higher grain moisture. These lines have potential for improving both agronomic traits and disease resistance and are being recycled to improve grain dry down. A study will be conducted in 2002 to evaluate the effectiveness of Gaucho, Cruiser, and Clothianindin seed treatments for Stewart's wilt management in sweetcorn. A preliminary study in 2001 did not provide sufficient data to evaluate seed treatments due to a low incidence of flea beetles.
Impacts
Lines being developed at the University of Delaware may be useful as genetic sources of resistance to European corn borer, an important insect pest in maize. The inbreds derived from GEM (Germplasm Enhancement of Maize) populations have potential to broaden the germplasm base of U.S. maize production.
Publications
- No publications reported this period
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