In order to compare the allelopathic potential of different wheat cultivars under severe competition with Phalaris minor Retz., an experiment was conducted as split plot in RCBD with three replications at experimental field of Agricultural Research Center of Golestan Province during growing season 2013-2014. The 12 wheat cultivars (Morvarid, Gonbad, N-87-20, N-91-8, N-91-9, N-91-10, N-91-14, N-91-17, Koohdasht, line 17, Karim and N-90-7 ) as main plots were planted in two subplots (weed-free and weed-infested with 50 P.minor individuals per square meter). Also, the allelopathic effects of different wheat cultivars on growth and germination of soybean crop, Euphorbia maculate L. and Euphorbia heterophylla L. weeds were separately compared in several laboratory experiments. All petri dish experiments were conducted as factorial in CRD with three replications. The treatments were wheat cultivars in twelve mentioned above levels as first factors and the concentration of wheat cultivars aqueous extracts in five levels (0, 25%, 50%, 75%, and 100) as second factors. Among different cultivars, N-90-7, N-91-8 and N-91-9 had the highest yield under weed free condition, but N-90-7 was more successful than the other cultivars under weed infestation condition too. The results of petri dish experiments showed that different levels of wheat extract had no significant effect on germination percentage of soybean. But E. maculata and E. heterophylla seed germination was affected by increasing extract dosages. Germination rate, length and dry weight of E. maculata and E. heterophylla seedlings were decreased as the extract concentration increased significantly. The results showed that some of wheat cultivars have allelopathic potential to reduce weed E. maculata and E. heterophylla growth. N-87-20 wheat cultivar was the most allelopathic potent plant among different wheat cultivars and it showed the highest inhibitory effect on E. heterophylla and E. maculata growth and germination.