Breeding winter wheat for a dual-purpose management system

Breeders attempt to conduct selection under environmental conditions repres entative 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 f orage for cattle grazing and harvesting grain, but breeding of cultivars li kely occurred in an environment managed for grain production. We tested the hypothesis that genetic improvements accrued over time in agronomic perfor mance 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 y ears, employing management components appropriate to each system, and using a historical set of 12 cultivars chosen for their widespread adoption in t he region. Substantial genetic improvement has occurred in hard red winter wheat yield, without adverse effects on test weight or grain protein conten t. The magnitude of genetic gain was higher in the grain-only management sy stem under which these cultivars were originally selected. In two of the th ree years, we found no significant trend for improvement in grain yield und er the dual-purpose system, prompting an expansion of our breeding objectiv es to incorporate selection pressure for dual-purpose adaptation.