One of the main reasons for decrease of crop yield is weed infestation. The reduction product forms and competition between weeds and crops attributed to Allelopathic interactions between them are not really considered. Weed free Phytotoxin from the seeds, remnants of destroyed materials, washed, affected the crop formation. When sensitive plants are exposed to compounds with allelochemicals components, germination and growth of these plants are impressed. In order to in this research effect of weed allelopathic of sorghum (Sorghum halepense) was studied on germination and seedling growth of wheat, Alvand cultivar. This experiment was carried out as complete randomized design in 3 replications in agronomy laboratory of Islamic Azad University of Yasuj Branch. Treatments were consisted of different concentrations of aqueous extract of different tissues of sorghum halepense (root, stem, leaf and seed) in 5 levels: 0, 7.5, 15, 22.5 and 30%. Aqueous extract of leaves, stems, seeds and roots of sorghum had a significant deterrent effect on wheat seeds germination. Interrace the most negative effect on seed germination of wheat was observed by allelopathic effect of sorghum seeds. Allelopathic effect of leaf and stem of this plant had significant deterrent effect on growth of wheat seedling length, although the root extract increased partial longitudinal growth of wheat seedlings. Extracts of different tissues of sorghum reduced wheat seedling fresh weight. Overall these results showed that the allelopathic activities of aqueous extract of weeds on wheat, Alvand cultivar had significant deterrent effects.
