Submitted to: International Wheat Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2000
Publication Date: 1/1/2001
Citation: CARVER, B.F., KHALIL, I., KRENZER, E.G., MACKOWN, C.T. BREEDING WINTER WHEAT FOR A DUAL-PURPOSE MANAGEMENT SYSTEM. INTERNATIONAL WHEAT CONFERENCE PROCEEDINGS. 2001. 119:231-234.
Interpretive Summary: In some years more than 50% of the winter wheat acreage in the U.S. southern Great Plains (SGP) is used for the dual purpose of grazing stocker cattle and then harvesting grain. Traditionally wheat breeding programs develop cultivars for grain-only production systems. We determined if it was necessary for wheat breeding programs to use a forage-plus-grain production system when selecting new wheat cultivars for release to farmer in the SGP. Twelve widely adopted cultivars representing more than 50 years of traditional breeding improvements in grain yield were compared using grain-only and graze-plus-grain production systems. The breeding gains for yield were more evident for the grain-only system. In two of the three years, the breeding gains for yield were not evident when the forage- plus-grain system was used. These findings have led us to expand our breeding objectives to include both production systems in the development of wheat cultivars for the SGP and allow us to add direct selection criteria for the forage component of wheat that is superior for dual- purpose production. These results will be useful to wheat breeders and agronomists seeking to improve winter wheat grazing and cropping opportunities for farmers in the SGP.
Technical Abstract: Breeders attempt to conduct selection under environmental conditions representative of the target environment. In the U.S. southern Great Plains, more than 50% of the wheat area may be used for the dual purpose of producing forage for cattle grazing and harvesting grain, but breeding of cultivars likely occurred in an environment managed for grain production. We tested the hypothesis that genetic improvements accrued over time in agronomic performance may be compromised, or be differentially expressed, in a forage-plus-grain system compared to the grain-only system under which improvement was initially targeted. Two field experiments were conducted in each of three years, employing management components appropriate to each system, and using a historical set of 12 cultivars chosen for their widespread adoption in the region. Substantial genetic improvement has occurred in hard red winter wheat yield, without adverse effects on test weight or grain protein content. The magnitude of genetic gain was higher in the grain-only management system under which these cultivars were originally selected. In two of the three years, we found no significant trend for improvement in grain yield under the dual-purpose system, prompting an expansion of our breeding objectives to incorporate selection pressure for dual-purpose adaptation.