[Effects of the additives and the combination of plants on Pb absorption, growth and quality of Dianthus superbus]

A pot experiment was conducted to study the effects of inoculation with arbuscular mycorrhizal (AM) fungi, neighboring plants (Trifolium repens), addition of EDTA and phosphate fertilizer on the performance of Dianthus superbus grown on Pb contaminated soil. The growth and quality of D. superbus were investigated to provide a theoretical basis for the scientific cultivation of Chinese herbal medicine. The results showed that the D. superbus with AM resulted in a significant inhibition of Pb uptake (P＜0.05), increase of root development and root/shoot ratio compared to untreated control plants, and with the highest content of active component. The content of emodin reached 6.5 mg·g^-1. When planting with T. repens the reducing effect of Pb absorption induced by AM fungi was insignificant. The quality of D. superbus decreased, and the emodin content decreased to 3.2 mg·g^-1, which was lower than that in the control group. However, D. superbus showed improved growth and active ingredients, and the lowest Pb content (1.3 mg·g^-1) due to AM fungal inoculation. The addition of EDTA decreased the growth of D. superbus, but promoted the absorption of Pb, with the Pb content to 340.0 mg·g^-1. Calcium phosphate showed the ability to immobilize other heavy metals in the soil, therefore might be more suitable to be applied in the conditions of compound pollution. Considering all of the results, AM fungi play a positive role in protecting the safety and quality of Chinese herbal medicine.