This research was carried out to study allelopathic effect of aerial and underground part of Eucalyptus camaldulensis on germination and early growth seedling of Vicia villosa, Onobrychis sativa, Festuca arundinacea and Trifolium rigidom. The extraction was provided from aerial and underground part of Eucalyptus camaldulensis. Different concentrations of this species (0, 25, 50, 75 and 100 %) was provided by adding distilled water. Then completely randomized design with five treatments and four replications was used to analyze the data. Results indicated that there were significant differences among all traits (germination percentage, germination speed, root length, shoot length, plant length and seed vigor index) except for germination percentage in Vicia villosa (P<0.01). Means Comparison indicated germination percentage and speed and primary growth indices decreased by increasing of extract concentration. The highest germination percentage and speed, length of radical and plumule and seed vigority were belonged to control treatment and the lowest length belonged to 100 % extraction. Germination and early seedling growth of 4 species were reduced significantly by increase of extract concentration so that Onobrychis sativa and Trifolium rigidom indicated more sensitive to allelopathic effect of Eucalyptus camaldulensis.
