In order to evaluate the adaptation and determine the highest yielding variety, 14 rapeseed (Brassica napus) cultivars/lines were studied in this research. The experiment was conducted in a Randomized Complete Block
Design with four replications in five locations (Karadj, Kermanshah,.Uromieh, Moghan and Hamedan) for three growing seasons during 1994-97. Statistical analysis was done on four main characters' data including:seed yield, thousand-seed weight, oil percentage and yield. Simple and combined analysis of variances showed that there were significant diffrences between genotypes. In order to evaluate interactions and determine the adaptation of genotypes, six different stability analysis methods were used in this study including: 1) Environmental variance or Roemer method, 2) Environmental coefficient of variation (c.V.) or Francis and Kannenberg method, 3) Finlay and Wilkinson's regression method, 4) Eberhart and Russell's regression method, 5) Lin and Binn's years within location mean squares method, and 6) The years within location c.v. method. The obtained results through all these methods were nearly analogous. Regarding seed and oil yield, all methods introduced the line Karaj-16 as the most stable and highest yielding genotype with good general adaptation. The varieties QUINTA, JETNEUF and Y ANUSH also were recognized as the next stable and high-yielding cultivars with average general adaptation. These varieties can be grown in mentioned testing sites or regions with similar climatic conditions. The results showed that seed yield has the most effect on oil yield and through breeding or selection for high seed yield, high oil yield will be obtained as well.
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