The Effects of Arbuscular-Mycorrhizal Fungi and Phosphorous on Arsenic Uptake by Sunflower Plant in Soils Spiked with Arsenite and Arsenate

Arsenic is a highly toxic metalloid in group 15 of periodic table. The information on environmental behaviour of arsenic, however, is still scarce. Contamination of soils and water with arsenic and antimony due to their widespread industrial application and mining activities has raised serious environmental concerns. Nearly all Arsenic-contaminated soils results from human activities and it has different environmental and sociological impacts. Various strategies and methods have been proposed for environmental management and remediation of contaminated soils. Among all methods, the phytoremediation is receiving more attention due to its cost effective and environmental friendly characteristics. In the case of arsenic contaminated soils, there are effective factors such as soil fertility, nutrients content and microorganisms function, which can improve the uptake of As by plants. Up to now, several studies have been evaluated the effects of symbiotic fungal association in plants on increasing nutrients and toxic elements uptake. Many of authors reported that the mycorrhizal symbiosis increases the uptake of toxic elements in root and shoot of plants and consequently improve the efficacy of phytostabilization and phytoextraction processes. There are conflicting results about the effect of arbuscular- mycorrhizal fungi (AMF) on As uptake by various plants. Chen et al. (4) found that Glomus mosseae symbiosis with plant reduces As concentration and enhance phosphorus content in shoot and root of plant. Whilst Cozzolino et al. (7) reported that the AMF increases as concentration in shoot and root of cabbage. Phosphorus has important role on mycorrhizal symbiosis and also As uptake by plants. Therefore, current study was conducted to evaluated effect of Glomus intraradices and Glomus mosseae symbiosis with sunflower and also soil phosphorus concentration on uptake of arsenic from arsenite and arsenate contaminated soils.
The soil sample (Typic Haplorthids) was collected, air dried and passed through 2 mm sieve and then were heated in 80 centigrade degree temperature for two times. A pot experiment was conducted in a completely randomized design with factorial arrangement and three replications in greenhouse condition. The experimental factors included two species spices of inorganic As (50 mg kg-1 of Arsenite and Arsenate), two levels of phosphorus (0 and 60 mg Kg-1) and three spices of arbuscular mycorrhizae (control, Glomus intraradices and Glomus mosseae). Soil samples spiked with Na2HAsO4.7H2O, NaAsO2 (Arsenite and Arsenate) and Ca (H2PO4)2 (phosphorus) and incubated in greenhouse condition for 4 week. Sunflower seeds were planted and seedlings harvested after 60 day of sowing and then dry weight of sunflower, concentration of As and phosphorus in shoot and root of plant and root colonization percentage determined using standard methods.
The results revealed that Glomus intraradices (GI) and Glomus mosseae (GM) symbiosis significantly (P