Genetic analysis of Agronomic Traits in Generations Derived from the Cross of MO17 and B73 Maize Inbred Lines Under Water Deficit Stress

The selection of suitable yielding maize cultivars to water deficit is one of the main objectives of the breeding programs. Therefore, selection of a suitable breeding method for better productivity from genetic potential of stress tolerance and understanding the type of controlling genes action and their inheritance is very important. In this regard, genetic analysis of some of the agronomic traits of the generations resulting from cross between corn inbred lines MO17 (Tolerant to stress) and B73(stress sensitive) including: F1,F2,F3,BC1 and BC2 along with parents in three irrigation conditions (normal, 50 and 75 millimeter evaporation from class A evaporation pan) was evaluated in 2017-2018. Experiment was conducted in each irrigation conditions in a randomized complete block design with 20 replications. The traits including grain yield per plant, biomass per plant, 1000 grain weight, ear diameter, ear weight and rows number were measured. Combined analysis revealed that there was a significant difference between the studied generations for maize agronomic traits. The results of the scaling test indicated the existence of epistatic effects for most traits such as grain yield per plant, biomass per plant and1000 grain weight under different irrigation conditions In most of the traits such as grain yield per plant, biomass per plant, row number per ear and 1000-grain weight, dominance effect was significant at 5% and 1% probability level. About rows number three-parameter model was the best fit model, in all three conditions. For most of studied traits, six parameters models were significant in different irrigation conditions, but was not significant for plant height under normal irrigation conditions and 75 mm evaporation due to maternal effects, gene association and multiple chi-square epistasis. Estimation of the dominance degree above 1 for grain yield and less than 1 for ear diameter in all three irrigation conditions  indicated that there was a phenomenon of over dominance and incomplete dominance in the control of them. High levels of genetic broad sence and narrow sence heritability suggested that genetic effects and additive effects have a greater role in the inheritance of 1000 grain weigth in all three irrigation conditions.