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This study was conducted to identify markers associated with some kernel traits in bread wheat in two separate experiments under field and laboratory. One hundred wheat genotypes were evaluated in an alpha lattice experimental design with two replications. Grain hardness, seed length, seed width and thousand kernel weights were measured. Association mapping was performed based on 96 unlinked and 22 SSR QTL linked markers, using structure and Tassel software. Correction for population structure was performed using genome wide SSR markers so that genotypes were divided into six sub-populations. Totally, 35 SSR markers linked to traits were detected eight of them being QTL linked markers and other markers that were linked to traits, were used to investigate population structure. The QTLs linked markers were as follows: Chromosomes 5B, 5D and 6D had three QTL for grain hardness. Nine QTLs were detected on chromosomes 1A, 1B, 2A, 2B, 2D, 5B, 5D, 6D and 7B for kernel length, kernel width and thousand kernel weights. The results of this study demonstrate that association mapping is a useful approach to complement and enhance previous QTL information for marker-assisted selection in wheat.

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In order to study genetic diversity, heritability and relation of some important traits with grain yield in bread wheat, 20 bread wheat irrigated lines evaluated using a randomized complete block design with three replications during two cropping cycles/years. Based on combined analysis results, there were a significant difference between genotypes. Also, in all traits, coefficient of phenotypic variation was greater than coefficient of genetical variation, indicating the effect of environment on investigated traits. The significant correlation between grain yield and number of days to maturity, spikes per m2 and the grains per spike. number of days to heading and number of days to maturity had highest heritability among traits, with 87 and 69%, respectively. Results of this showed that selection of early heading or shorter no. of days to heading and early maturing or shorter number of days to maturity is recommended to breeders for selection materials favorable for terminal warm condition and water shortage, preventing grain yield reduction. Results of cluster analysis showed that genotypes are divided in six groups. Totally, six superior genotypes from the fourth cluster were selected as superior lines. Based on bi-plot analysis, genotypes 14 and 5 showed the lowest genotype × trait interaction, but genotypes 16 and 8 showed the highest genotype × trait interaction.