Estimation of Genetic Parameters for Maturity and Grain Yield in Diallel Crosses of Five Wheat Cultivars Using Two Different Models

Wheat maturity is important for its adaptability to different environments and geographical regions. In order to obtain genetic information for maturity and grain yield, five wheat cultivars of Cross adl, Marvdasht, Chamran, Shiraz and Darab2 were crossed for producing one-way diallel crosses that were analyzed using two models of Griffing (1956) and Jinks and Hayman (1953). Parents and their F2 progenies were cultivated at two locations of Shiraz and Zarghan, Iran, in 2010-2011. The traits of interest were days to heading (DDH) and maturity (DDM), grain filling duration (GFD), grain yield per plant (GY) and plant height (PH). Genotype × location interaction was significant for PH and GFD but there was no interaction for DDH, DDM and GY. The variances due to general (GCA) and specific (SCA) combining abilities were significant for all the traits. Therefore, both additive and non-additive genetic components were not equally involved in genetic control of the characters studied. The GCA × location interaction was only significant for PH and GFD, an indication for the effects of environment on additive components. The Baker (1978) ratio for DDH (0.90 and 0.91 at Zarghan and Shiraz locations respectively), DDM (0.81 and 0.82) and GY (0.89 and 0.87) under both locations and for PH (0.88) at Shiraz showed the higher importance of additive variances in the genetic control of these traits. The GCA estimates revealed that Chamran for dwarfness, early heading and maturity and GFD, Darab2 for dwarfness, early heading and maturity, Marvdasht for GFD and GY were the best combiners. Graphical analysis and the average degree of dominance (less than 1) showed that gene action for all the traits was of partial dominance type.