investigation of the metal bioremediation ability of two populations of peganum harmala

The present study aimed to investigate the effects of zinc exposure (0, 1, 5, 15, 30 mg/l zinc) on the biochemicaland physiological parameters of peganum harmala seedlings. two populations (metallicolous and nonmetallicolous)were compared in zn tolerance, zn accumulation, photosynthetic pigments, and enzymaticantioxidant activities. plants were treated with zn at concentrations of 0, 1, 5, 15, and 30 mg/l for 14 days. thestudy results showed that the increase of zn concentration in the nutrient solution reduced shoot length, rootlength, root dry weight, shoot dry weight, chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid inboth populations; however, the accumulation was more pronounced in metallicolous populations (m) than innon-metallicolous (nm) ones. in response, the activities of antioxidant enzymes such as guaiacol peroxidase,lipoxygenase, superoxide dismutase, catalase, and ascorbate peroxidase were enhanced zn exposure in bothpopulations. moreover, it was found that the metallicolous population of p. harmala had a greater capacityto adapt to oxidative stress caused by zn than the non-metallicolous population, and antioxidative defensein the metallicolous population of p. harmala might have played an essential role in zn tolerance. therefore,p. harmala seemed to be a suitable candidate for accumulation; however, it was recommended that furtherinvestigations be carried out to explore its metal remediation ability. it is concluded that p. harmala can be apotential candidate for bioremediation of zn contaminated soils.