This test was conducted on laboratory condition to investigate the allelopathic effect of Eucalyptus camaldulensis on germination and early seedling growth of Onobrychis sativa. Pretreatment with gibberellic acid and salicylic acid also was used to decrease the adverse effect of allelopathic components. Three levels of gibberellic acid (125, 250 and 500 ppm) and salicylic acid (100, 200 and 300 mg/L) and five extract levels of Eucalyptus camaldulensis (0, 25, 50, 75 and 100 %) was used in the test. This experiment was carried out as factorial experiment based on a randomized completely design with four replications. The results of ANOVA and compare mean test showed that Eucalyptus camaldulensis extract had inhibitive effect on germination and early seedling growth of Onobrychis sativa. Early seedling growth of Onobrychis sativa increased by pretreatment of seeds in chemical stimulators so that the highest effect was observed in gibberellic acid. Interaction effects of allelopathic and pretreatment with chemical stimulators were significance on germination percentage and speed, root, shoot and plant length and seed vigour index.
