Influence of arbuscular mycorrhizal fungus (Glomus caledonium) on maize seedlings grown in copper contaminated soil

A greenhouse pot experiment was carried out with maize seedlings (Zea mays L., cv. nongda 108) grown in a calcareous soil treated with two levels of copper (Cu: 50 and 150 (mg/kg)) and without. Then an arbuscular mycorrhizal fungus (AMF), Glomus caledonium was inoculated and the control as set up exactly in the same way except no fungi were inoculated. Mycorrhizal effects were investigated through the comparing of plant growth, Cu uptake and distribution in mycorrhizal and non-mycorrhizal seedlings in order to realize the possible mechanisms of heavy metal resistance of mycorrhizal fungi and application of the fungi in bioremediation of Cu-contaminated soils. The results showed that the fungal infection rate was approximately 55% in the soil supplied with Cu of 150 mg/kg, indicating the high Cu-tolerance of the fungus. At the same time, the biomass and length of the mycorrhizal roots were enhanced by 108.4% and 58.8%, (respectively,) compared with no mycorrhizal fungi. The shoots weight reached 10.58 g/pot in high Cu treatment with (mychorrizal) inoculation, which was significantly higher than the Cu blank control treatment without the fungus. The Cu (tolerance) of mycorrhizal seedlings could be attributed to the improvement of phosphors absorption and translation, soil acidification inhabitation and reduction of soluble Cu content in soil. It is necessary to point out that Cu concentrations in (mycorrhizal) seedlings, compared to non-mycorrhizal plant, was decreased by 24.3% in shoots and 24.1% in roots, which was grown in the soil treated with Cu of 150 mg /kg. However, in contrast to the amounts which were increased by 28.2% in shoots and 60.0% in roots, respectively. At this point, arbuscular mycorrhizal fungus(Glomus caledonium) played an important role in the bioremediation of heavy metal contaminated soils.