Effects of Arbuscular Mycorrhizal Inoculation and Cattle Manure on Cadmium Uptake by Tobacco

Cd is a highly toxic pollutant commonly found in tobacco (Nicotiana tabacum L.) plants, which can enter the human body via smoking, and thus create a potential health risk to smokers. Here, a pot culture experiment was conducted to determine the influence of arbuscular mycorrhizal (AM) inoculation with Glomus intraradices BEG 141 and cattle manure on the growth and Cd uptake by tobacco plants. Four levels of Cd (0, 1, 10, and 100 mg/kg), and four treatments, including nonmycorrhizal inoculum (C), AM inoculation (M) and cattle manure (N), singly or in combination (MN), were applied to the sterilized soil. Mycorrhizal and nonmycorrhizal tobacco seedlings were prepared and transplanted to pots after they were colonized. The plants were harvested after 70 days of growth in a greenhouse. Results showed that, at all Cd addition levels, AM inoculation and cattle manure, applied singly or in combination, all increased shoot and root dry matter yields of tobacco significantly, with an order of MN > M > N > C. AM inoculation improved P nutrition and reduced Cd concentrations in shoots and roots. Amendment with cattle manure exhibited significant promoting effects on plant growth under most Cd addition levels except the 100 mg/kg, and no significant effects on Cd residues in tobacco plants under severe pollution. The higher soil pH and the lower DTPA--extractable Cd concentrations may be contributing factors leading to lower Cd phytotoxicity and higher growth promotion by AM inoculation and/or cattle manure. The present findings suggest a great potential of AM fungi and organic manure for both production of high--quality tobacco and phytoremediation of Cd--polluted soils.