The allelopathic effect of Peganum harmala L. on two rangeland species (Agropyron desertorum and Agropyron elongatum)

Different responses of some weed species to Peganum harmala L. allelochemicals requires to find resistant species to this plant (with high allelopathy potentiality) in order to improvement of critical rangelands. In order to determine allelopathic potential of Peganum harmala L. on two important rehabiting species such as Agropyron desertorum and Agropyron elongatum, the effects of factors of this donor plant as kinds of powder (aerial and uederground parts), propertion levels (0, 5, 10, 15 and 20%) and phenology stages (vegetative, flowering and seeding) were measured on germination (speed and percentage) and grow (root and stem length) indices in factorial design with 3 replications. Another experiment was done to investigate the effects of natural habitate soil in a rondom design with 3 replications. Allelochemicals effect in seeding stage on all dependent variables of two recipient species was lower than vaegetative and flowering stages. All indices was decreased with an increase in powder propertion. Significanthly negative response of germination and growth indices was observed in allelochemicals of aeria part and this response was severe in Agropyron desertorum Considering the negatively lower response of Agropyron elongatum to large amount of Peganum harmala dry matterr powder the effects of natural habitate soil, Agropyron desertorum is prefered for improving rangelands with Peganum harmala bed. Harvesting of aerial parts of Peganum harmala before and after rehabitation projects are recommonded for decreasing of its allelopathic effects.