Inheritance of Pericarp Thickness in Short Season Maize Inbreds

Pericarp thickness of 16 short-season inbred lines of corn (Zea mays L.) ranged from 35 to 126 μm with an overall mean of 82 ± 5 μm. The mode of inheritance of this trait was studied in two experiments. Two inbreds representing the extremes of pericarp thickness, their F 1 and F 2 generations, and both first generation backcrosses were included in Experiment 1. The inheritance of pericarp thickness proved to be quantitative in nature. All gene effects were significant, but epistatic effects, particularly dominance × dominance, were the largest in this particular cross. This could have resulted from bias due to linkage disequilibrium. Experiment 2 was a diallel set of 5 inbreds to include the parents and all possible single crosses, but not reciprocals. Diallel graphic analysis of these data indicated partial dominance for thin pericarp with minimal epistasis. Analysis II of Gardner and Eberhart showed that the mean square for line effects was several times larger than the heterosis estimates, indicating a high level of additive gene effects. The narrow sense heritability estimate was 72%. Thus selection for specific pericarp thickness should be effective and relatively rapid.