Gene action for some agronomic traits in maize (Zea mays L.)

Seven maize inbred lines were crossed in a complete diallel cross design at the Seed and Plant Improvement Institute, Karaj, Iran, during the 2006 growing season. The parents and 42 F1 hybrids were grown in the research field of Islamic Azad University of Firoozabad, Firoozabad, Iran, using a Randomized Complete Block Design (RCBD) with three replications, during the 2007 growing season. The Hayman method was used for data analysis. Results indicated over-dominance gene effects for days from silking to physiological maturity, days from anthesis to physiological maturity, plant height, kernel depth, number of rows per ear and grain yield. The most appropriate strategy for the exploitation of these effects is to obtain hybrid cultivars and evaluate these characteristics in hybrid combinations. The gene effect for days from emergence to physiological maturity and number of kernels per row was complete dominance, suggesting that reciprocal recurrent selection would be effective. Ear leaf area and ear length were controlled by partial dominance, indicating that additive gene effects were more important than non-additive gene effects for controlling the inheritance of these traits. Therefore, improvement of these traits through selection of breeding materials is highly feasible. Broad-sense heritability ranged between 47.4% and 89.4% for days to physiological maturity and number of rows per ear; however, narrow-sense heritability varied between 7.3% and 50.6% for days from anthesis to physiological maturity and ear leaf area, respectively. Non-additive gene effects were predominant for controlling the majority of traits.