In the present study, two bread wheat crosses were subjected to generations means analysis in order to determine the types of gene effects controlling grain yield per plant and 1000 kernel weight under favorable and heat stress under filed conditions, as well as tetrazolium chloride (TTC) reduction, chlorophyll a and b content at seedling stage. The A, B, C, and D scaling tests for grain yield per plant, 1000-KW and chlorophyll a and b content in the two crosses at both environments indicated the non adequacy of the simple additive-dominance model of inheritance, except for 1000-KW in cross 2 under heat stress condition and TTC in both crosses. The additive effects were found to be significantly (P≤0.05) moderate for all studied traits under the two environmental conditions, except for grain yield per plant in cross 1 at favorable environment. Meanwhile, the dominant parameter (h) was significant (P≤0.05) for all traits in the two crosses under the two environmental conditions as well as seedling traits, except for TTC in cross 1 and 1000-KW under favorable condition in cross 2. Grain yield per plant predominantly controlled by dominance gene effect (h) and the magnitude of dominance effect was higher than additive gene effects (d), while the dominance effects were higher than the additive effects for 1000-KW in cross 1 under both environmental conditions. The broad and narrow-sense heritabilities for 1000-KW in cross 2 under heat stress condition were high in magnitude being 0.85 and 0.66, respectively. For chlorophyll a and b content and TTC, the dominance effect (h) was higher in magnitude than the additive gene effect (d). The narrow-sense heritability for TTC was higher in magnitude of 0.59 and 0.63 in crosses 1 and 2, respectively. These results indicated that TTC reduction and chlorophyll content are powerful indicators for screening wheat genotypes for heat tolerance. Out of eight SSR markers used to identify those which associated with heat tolerance using bulked segregant analysis (BSA), the Xgwm566 marker was found to be associated with Chlorophyll a content, whereas the Xwmc603 and Xgwm456 markers were associated with TTC, indicating that these markers would be considered as markers associated with heat tolerance in wheat and could be used for selecting heat tolerance genotypes in wheat breeding programs.