Effects Of Arbuscular Mycorrhizal Fungi On Heavy Metal Residues In Tobacco

With the rapid development of the industry and agriculture, there are more andmore environmental problems, especially heavy metal pollution. In recent years, thereare many reports that heavy metal exceeded in tobaccos. Arbuscular mycorrhiza (AM)is the most widely distributed type of mycorrhiza in nature, which is common in avariety of habitats, including soil contaminated by heavy metals. Under the pollutionof heavy metal, arbuscular mycorrhizal fungi (AMF) can improve the growth of plants,reduce the toxicity of heavy metals to plants, and affect the absorption and transport ofheavy metals by plants. Cadmium and lead were the target of heavy metals in thisstudy. K326was as tested plant because of its large cultivation in China. We intendedto study the effect of AM inoculation on heavy metal content of tobacco undersimulated pollution conditions and to assess the role of AMF in the reduction of heavymetal residues in tobacco.Firstly, a greenhouse pot experiment was carried out under the conditions ofdifferent levels of lead pollution (0,350,500, and1000mg/kg) to study the effects ofAM inoculation and cattle manure on the growth and the residue of Pb in tobacco. Theresults indicated that at all levels of Pb, the treatments of AMF inoculation (M), cattlemanure (N), AMF inoculation and cattle manure (MN) reduced the bioavailability ofsoil Pb, improved the nutritional condition of tobacco and promoted the growth oftobacco. The residue of Pb was reduced by AM inoculation at high pollution levels andcattle manure significantly reduced the residue of Pb in tobacco under mild andmoderate levels of Pb, but the treatment of MN reduced the residue of Pb at all thelevels of Pb.Secondly, a greenhouse pot experiment was carried out under the conditions ofdifferent levels of cadmium pollution (0,1,10and100mg/kg) to study the effects ofAM inoculation and cattle manure on the growth and Cd uptake of tobacco. Resultsshowed that both AMF inoculation and cattle manure reduced the Cd contents of shoot and root, especially under the condition of heavy pollution. AMF inoculation and cattlemanure increased the production of tobacco, reduced the heavy metal residue and thetwo were synergistical, indicating that they had the potential to be used to improve thetobacco’s quality safety.Lastly, in a greenhouse the pot experiment was carried out under the conditions ofdifferent levels of lead/cadmium pollution (0/0,350/1,500/10and1000/100mg/kg) tostudy the effects of AM inoculation and cattle manure on growth, P nutrition and theresidues of heavy metals. The results suggested that the treatments of M and MNpromoted tobacco growth, improved P nutrition, increased Pb and Cd tolerance oftobacco, and reduced the residues of Pb and Cd in tobacco and the contents of DTPA-Pb and DTPA-Cd in soil. On the whole, the treatments of M and MN on growth,nutritional condition, heavy metal uptake of tobacco and some soil parameters wereshown synergistically, especially at high levels of Pb-Cd pollution.The experiments show a promising potential of AMF and cattle manure to reducethe heavy metal residues in tobacco and improve tobacco’s quality safety. Furthermore,the two can be synergistically applied to tobacco’s production in soil contaminated byheavy metals.