Among the flowering parasitic plants, broomrape is the most problematic ones which cause highly destructive damage to both crops and orchards. After soybeans, canola ( Brassica napus ) is the second most important oilseed in the world. Broomrape parasitism in canola could caused a significant yield damage. A pot experiment was conducted to study the effect of orobanche aegyptiaca on some cultivated and wild Brassica species in 2012 January to 2013 July in research station of Isfahan university of technology, hsfahan , Iran. The experiment was set up in a factorial experiment based on randomized complet blocks design with six replications. Treatment include two levels of infestation of broomrape seeds (control vs infested) and 11 genotypes of Brassica genus, consist of 5 wild species including: B. nigra , B. juncea , B. carnita , B. rapa and B. oleracea and 6 cultivar of B.napus (RGS, Opera, Hayola60, Hayola 401, Zarfam and Sarigol). At flowering stage of rapeseed, tubercle number and dry weight, shoot number and dry weight of O. aegyptiaca were determine. Leaf number, plant height, leaf area, Seed number in pod, number pod in plant, 1000-seed weight, seed yield and shoot and root dry weight of rapeseed were determined at the physiology maturity stage. Sampling from treatments were done in flowering and maturity growth stage of rapeseed. All genotypes were host of orobanche . Although the reaction of wild and cultivated genotypes to orobanche parasitism were different. The wild genotyoes were shown less damage than the cultivated genotypes. Some cultivars such as opera and zarfam could high stimulate the germination of orobanche seeds. These cultivars can be grown as a catch crop to deplet the broomrape seed bank in the soil . B.juncea was more resistant than other genotypes in term of studied traits and yield reduction. Among the studied traits in rapeseed, yield was more affected by broomrape parasitism than other traits. So, for all the genotypes except B.juncea seed yield loss was over 70%. In conclusion based on the results of this study it can be said that in order to prevent the destructive effect of broomrape on canola yield both serious weed management works and attention plant breeding program to release resistant variaties shoud be considered.
