Five cotton cultivars and their parents were tested for induction of germination of Orobanche cumana Wallr.(sunflower broomrape) seeds in pot and field experiments. Germination rates induced by cotton root extracts were the highest followed by stem extracts then leaf extracts. Cotton seedlings at the six-leaf stage induced higher germination than seedling at the two-and four-leaf stage, in all five cotton cultivars and their parents. In the field, the highest concentration of cotton root extracts gave the highest germination rate of O. cumana, and the lowest concentration of cotton root extracts gave the lowest germination rate. Methanol extracts of cotton rhizosphere soil gave the highest germination of O. cumana. In general,the root, stem and leaf extracts were more active at the sixleaf stage than other seedling stages. In conclusion,extracts of cotton rhizosphere soil and tissues have high activity in the seedling stage. Extracts of cotton across the whole growing season were able to induce O. cumana germination but displayed significant cultivar interactions. Five cotton cultivars and their parents were tested for induction of germination of Orobanche cumana Wallr. (Sunflower broomrape) seeds in pot and field experiments. Germination rates induced by cotton root extracts were the highest following by stem extracts then leaf extracts. Cotton seedlings at the six-leaf stage induced higher germination than seedling at the two-and four-leaf stage, in all five cotton cultivars and their parents. In the field, the highest concentration of cotton root extracts gave the highest germination rate of O. cumana, and the lowest concentration of cotton root extracts gave the lowest germination rate. Methanol extracts of cotton rhizosphere soil gave the highest germination of O. cumana. In general, the root, stem and leaf extracts were more active at the sixleaf stage than other seedling stages. In conclusion, extracts of cotton rhizosphere soil and tissues have high activity in the seedling stage. Extracts of cotton across the whole growing season were able to induce O. cumana germination but exhibited significant cultivar interactions.