Plant tolerance, accumulation and remediation of Pb by three rangeland plant species in a calcareous soil in west Azerbaijan province

The objective of this study was to evaluate the Pb tolerance, potential for accumulation and remediation of Pb of Hyoscyamus (Hyoscyamus niger L.), Onopordum (Onopordum acanthium L.) and Centaurea (Centaurea cyanus L.), native to Western Azerbaijan region. For this purpose, a soil was selected and spiked uniformly with different concentrations of Pb (0, 250, 500 and 1000 mg Pb kg-1 soil). Then plants were grown in pots containing the contaminated soil. This study was carried out under greenhouse condition as a randomized complete block design and in three replications. At the end of growth period, dry matter yields of root and shoot and Pb concentration in the root and shoot of plants, were measured. Also, the relative yields (RY) of root and shoot, stabilized Pb in roots (MS), extracted Pb by shoots (ME), bioconcentration factors (BCF and mBCF), modfied bioaccumulation factor (mBAF) and translocation factor (TF), were calculated. Results indicated that with increasing soil Pb contamination, yields of root and shoot and tolerance of plants decreased, while shoot and root Pb concentration, stabilized Pb in roots and extracted Pb by shoots increased. There was no significant difference (P > 0.05) among tolerance index (RY) of plants. In this study, maximum Pb accumulation was recorded in root of Onopordum (average of MS, BCF and mBCF 27 µg pot-1, 0.102 and 6.09 respectively) and maximum accumulation of Pb in shoot was observed for Onopordum (average of ME, BCF and mBCF 45 µg pot-1, 0.066 and 3.79 respectively) and Centaurea (average of ME, BCF and mBCF, 43 µg pot-1, 0.061 and 3.6 respectively). Therefore, Onopordum and Centaurea with a high biomass in native condition, might be effective in remediation of Pb contaminated soils, especially, in low levels of contamination.