HERITABILITY AND GENE EFFECTS OF SOME ROOT TRAITS IN MAIZE UNDER WATER DEFICIT STRESS CONDITIONS
To study of genetic structure in maize generations under water deficit conditions, the seven maize generations (MO17 and B73 as parents, F1, F2, F3, BC1, and BC2) were grown under normal irrigation (N), 50 (I1) and 75 (I2) millimetre evaporation from class A evaporation pan at the University of Tabriz farm. Three experiments were conducted in a randomized complete block design with 20 replications. The root traits including root length, root volume, root diameter, root number, root fresh weight, root dry weight were measured. A combined analysis revealed that there was a significant difference between the studied generations for maize root traits. The results of the scaling test indicated the existence of epistatic effects for all traits except the root number under different irrigation conditions. In most of the traits, the dominant effect is significant. The three-parameter model was the best fit model for root number, in three irrigation conditions. For most of the studied traits, six parameters and five parameters models were significant in different irrigation conditions, however, some models were not significant under irrigation conditions, due to because of existing maternal effects, genetic affinities, and multiple epistasis. Estimation of the dominance degree above 1 in some of the traits under different irrigation conditions indicated that there was a phenomenon of overdominance incomplete dominance in the control of them. High levels of genetic broad sense and narrow sense heritability suggested that genetic effects and additive effects have a greater role in the inheritance of most traits under different irrigation conditions.