Evaluation of Epistasis in a Selected Group of S\u3csub\u3e1\u3c/sub\u3e Lines of Corn

This study was conducted to test for epistatic gene effects in a group of S1 lines showing very low specific combining ability in previous testcrosses with a single cross hybrid as the tester parent. Epistatic gene effects were measured as deviations of the observed from predicted double cross performance. The predicted double cross performance was based upon three-way cross performance of the selected S1 lines. A group of S1 lines being tested for specific combining ability with a single cross tester produced results which indicated that epistatic gene action was present. A group of these S1 lines showing high specific combining ability were selected to test for epistatic gene action. Three-way crosses and double crosses were made using the S1 lines and the single cross, Wf9xN6. Two replications of the three-way crosses and double crosses were planted 1965 and 1966. Double cross performance was predicted using the three-way cross data for yield and moisture of grain at harvest. Advisor: John H. Lonnquist