This study was conducted at the research farm of Isfahan University of Technology in 2007 to investigate genetic variability for different agronomic traits in 16 cultivars of sesame. A randomized complete block design with three replications was used in the experiment. There were significant differences among the genotypes for all of the studied traits such as capsules/plant, seeds/capsule, 1000-seed weight, seed yield/plant and seed yield/plot. The phenotypic coefficient of variation were greater than the genetic onces for all the traits, but their differences were so small in most of the traits. The highest phenotypic and genetic coefficients of variation were obtained for branches/plant and the lowest was found for days to flowering. High broad-sense heritability was observed for all the traits. Days to flowering, capsules/plant, seeds/plant, 1000-seed weight, biologic yield and harvest index had high and positive correlation with both seed yield/plant and seed yield/plot. The result of stepwise regression showed that capsules/plant, 1000-seed weight and seeds/capsule explained 79% of the variation for seed yield/plant. Capsules/plant, 1000-seed weight and seeds/capsule were also more important component of seed yield/plot and explained 75% of the variation for seed yield/plot. The result of path analysis indicated that 1000-seed weight had the most direct and positive genetic effects on seed yield/plant and seed yield/plot. In general, the result of this study showed that there was high genetic variation among cultivars for all of the studied traits and selection can be effective to improve them. In breeding programs of sesame, capsules/plant, seeds/capsule and 1000-seed weight can be used as selection criteria to improve seed yield.
