Alternative maize heterotic patterns for the northern Corn Belt

Development of maize (Zea mays L.) inbred lines is based on the identification and utilization of heterotic groups and patterns. The objective of this research was to identify alternative heterotic patterns for the northern Corn Belt. Ten maize populations [BS5, BS21 (R)C7, BS22(R)C7, CGL(S-1-S-2)C5, CGSS(S-1-S-2)C5, LEAMING(S)C4, NDSAB(MER)C12, NDSCD(M)C10, NDSG(M)C15, and NDSM(M) C7] were crossed in a diallel mating design. The 45 F, crosses along with nine checks were evaluated in experiments with two replicates at each of four North Dakota and three Iowa locations in 2002. Data were collected for grain yield, harvest grain moisture, and root and stalk lodging. Analyses of variance were performed following the Gardner and Eberhart Analysis III model. Differences among genotypes existed for all of the traits, and the general combining ability (GCA) sums of squares were larger than the specific combining ability (SCA) sums of squares, indicating the predominance of additive genetic effects. Alternative heterotic patterns to 'Iowa Stiff Stalk Synthetic' (BSSS) X 'Lancaster Sure Crop' (LSC) were found for grain yield among early-maturing populations. The most promising crosses were those in which BS21(R)C7 was combined with CGL(S-1-S-2)C5, BS22(R)C7, NDSG(M)C15, LEAMING(S)C4, CGSS(S-1-S-2)C5, and NDSAB(MER)C12, and the heterotic pattern formed by BS22(R)C7 and LEAMING(S)C4. A strong association was found between the grain yield of populations per se and their GCA for harvest grain moisture. The population CGSS(S-1-S-2)C5 was the earliest among the 10 populations studied and had the best GCA value for grain moisture.