Estimation of Genetic Parameters and Combining Abilities in F3 Wheat Diallel Crosses

The present study was carried out to estimate genetic parameters and to investigate the inheritance of agronomic traits based on 5 ×5 diallel cross design in wheat. In this study, progenies of F3 generation of diallel crosses and their parental lines were evaluated in 2013-2014 growing season. Results showed that the highest broad-sense heritability estimate belonged to day to heading (DTH) (0.97) whereas lowest one was obtained for thousand-grain weight (TGW) (0.76). Jinks-Hayman and graphical analysis indicated that type of gene action for PH, DTH and GY was partial dominance whereas HI, GPS and TKW were controlled by over-dominance gene action. In Griffing analysis, the mean squares of GCA and SCA were significant for all traits. The ratio of GCA/SCA mean squares was significant for DTH which shows the higher contribution of additive gene effects in the genetic control of this trait. This ratio was not significant for other traits. The cultivar CrossAdl had the highest GCA effects for TGW (2.84**) and GY (8.55**). The estimation of SCA effects for diallel crosses showed that the CrossAdl × Marvdasht for GPS and TKW and Shiraz × Marvdasht for TKW and GY and HI had the highest SCA effects. Overall, it can be concluded that Cross-adl with best GCA effect for grain yield and progenies derived from crosses with desirable SCA effects can be used for increasing selection efficiency in wheat breeding programs. Also, Darab 2 and Chamran with negative GCA effects can be used in breeding programs for early maturity and dwarfness traits.