Successful maize (Zea mays 1.) breeding programs are based on specific heterotic patterns. The Iowa Stiff Stalk Synthetic x Lancaster Sure Crop heterotic pattern is widely exploited in U.S. maize breeding programs. Alternative U.S. heterotic patterns have been suggested, but they have received limited attention and improvement. The objectives of this study were to evaluate cultivar crosses between Leaming and Midland Yellow Dent cultivars before and after inbred progeny selection and to assess their potential as an alternative U.S. heterotic pattern. Grain yield had a midparent heterosis value of 4.9% before selection and 17.8% in the third cycle of selection. The increase of grain yield heterosis (12.9%) through selection was highly significant (P \u3c 0.01), and crosses between S1 generations showed an increased rate of inbreeding depression through selection. Grain moisture of the cross (20.1 %) was significantly (P \u3c 0.05) less than the Midland Yellow Dent (24.5%) cultivar but was not significantly greater than the Leaming (17.7%) cultivar. Root lodging strength was significantly improved through selection with 1.1 % root lodging of the cross after selection (midparent heterosis value of -73.2%). Intrapopulation recurrent selection was successful for increasing the heterotic expression between Leaming and Midland Yellow Dent maize cultivars. An interpopulation recurrent selection program between the improved selection cycles Leaming and Midland Yellow Dent seems desirable
