Wheat has proven to exert allelopathic effects against several weeds. A laboratory bioassay study was conducted to evaluate allelopathic interactions of wheat and Hordeum spontaneum using equal-compartment-agar method (ECAM). The experiments were done from May 2012 to July 2013 in Faculty of Agriculture of Isfahan University of Technology, Iran. I ECAM 400 ml glass beakers were filled with 60 ml of 0.4% water agar. The agar surface was divided in to two equal compartments that were occupied separately with donor and receiver plants. The plant material consisted of 16 cultivated genotypes and 10 wild genotypes of wheat (with different ploidy levels including di-, tetra-, hexa- and oktaploid) and one genotype of Hordeum spontaneum . The study consisted of two experiments. The first experiment evaluated the allelopathic effect of wheat genotypes on the seedling growth of wild barley, and second experiment investigated the response of wheat genotype to allelochemicals of wild barley. After determining the susceptible and resistant genotype groups of wheat to allelopathic effect of wild barley, antioxidant enzymes activity in both groups were measured. According to the results of the first experiment, Niknejhad, Backcross, Falat and TRI 9652 wheat genotypes were more and Yavaros, Bayat, Alamut, Bahar, Kavir, TRI 15593, TRI 11712 and TRI 18664 were less allelopathic respectively. Results of the second study suggested that Bahar, Kavir, Falat and Chamran genotypes were sensitive to the allelopathic activity of wild barley and Alvand, Alamot, Bam, Khoshki, Bayat, Back cross, Yavaros, TRI19322 and TRI9652 genotypes were rather resistant to allelopathic activity of wild barley. According to these results, Backcross and TRL9652 wheat genotypes that were both more allelopathic genotypes in the first study, and resistant genotypes to wild barely allelochemicals in the second study, can be used for weed suppresion in sustainable weed management. Results indicated that wild genotypes of wheat had more allelopathic effects than cultivarted genotypes. Tetraploid genotypes were more allelopathic than hexaploid genotypes and the oktaploid genotype outperformed the remaining genotypes of all poloidy levels in this regard. The results also indicated that antioxidant enzymes activity were higher in resistante genotypes compared to the susceptible genotypes of wheat to wild barley allelopathy effects. Key Words : allelopathy, equal-compartment-agar method , wheat germplasm, wild barley , antioxidant enzymes.
