Nineteen topcrosses of sorghum, paternal parent, and 19 male fertile maternal lines were evaluated to study the correlation between traits and path analysis to reach a selection pattern for yield based on different traits. The study was conducted at Isfahan University of Technology Research Farm in 2 planting dates (1st and 16, may), and two within row spacings (10 and 20 cm), in favorable and unfavorable environments. Significant differences were detected between the two environments for all of the traits studied, except test weight and panicle weight. The mean squares due to genotypes for all traits in each environment and genotype x environment interactions for all traits, except panicle lenght, were found to be statisticaly significant.The genetic correlation coefficients of grain yield with panicle lenght, plant height, test weight and panicle weight were positive and significant. The correlation coefficient of grain yield with number of days to 50% flowering was negative and significant. These results indicated that it is possible to increase grain yield by change in other traits. The results of path analysis and multiple linear regression, indicated that in favorable environment, the direct effect of panicle weight on grain yield was positive and high. The effect of test weight and plant height on grain yield was only indirect via panicle weight. It seems that tall plants have more nods in panicle and consequently more panicle weight. In unfavorable environoment, the number of days to 50% flowering explained more grain yield variation than did plant height. In this environment, also the direct effect of panicle weight on grain yield was positive and very high, but its indirect effect via test weight was negative and high. Number of days to 50% flowering had only a negative and high indirect effect on grain yield via panicle weight. The direct effect of test weight on grain yield in favorable environment was negative, but high. In this environment, also indirect effect of test weight on grain yield via panicle weight was positive and very high. Therefore, pan ide weight is the most important grain yield components and it is possible to increase the grain yield of sorghum by selection for this traits.
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