Effects of Mycorrhiza Fungi and Phosphorous on Uranium Uptake by Sunflower

Uranium is a radioactive element that occurs naturally in the earth’s crust. However, in some areas its natural abundance has been redistributed due to anthropogenic activities, where consequently results in high levels of contamination. In order to study the effect of mycorrhiza fungi and phosphorus on the uranium uptake by sunflower, a pot experiment is conducted under a controlled greenhouse condition. The experiment was carried out in a completely randomized design with three factors, including three species of arbuscular mycorrhizae (Glomus mosseae, Glomus intraradices, non-mycorrhizae), two levels of phosphorous (20 and 60 mg/kg), and one level of uranium (100 mg/kg). Plants were harvested after 60 days of experiment and dry weight of root and shoot as well as the uranium and phosphorus concentration in the shoot and root were determined. The results showed that mycorrhizae fungi increased the resistance of the plant against heavy metals. Also, mycorrhizae increased the uranium and phosphorous contents in the shoot and root of the sunflower plant. The dry weights of the shoot and root and also the uranium concentration in the shoot of the sunflower plant were significantly augmented by increasing phosphorus level. The results revealed that mycorrhiza symbiosis raised the uranium concentration in the root more than the shoot. Thus, it seems that arbuscular mycorrhiza has a potential for enhancing the phytostabilization of the sunflower plant.