White Clover (Trifolium repens L.) Growth in multi-metal contaminated soils and Fate of Modern Pesticides

Introduction: Heavy metal binding to soil organic matter (1) is leading to soil contamination and plant bioaccumulation (2). Reducing the bioavailability of soil metals by adding amendments to the soil could be suitable for mitigating heavy metal uptake by plants (3-4). For example the addition of Zeolite at 1% dose in metal polluted soil was the most efficient way for reducing the average Cd concentration in tobacco plants, as reported by Keller et al. (5). Methods: In that same spirit, we investigated the effects of heavy metals (Pb, Cd, Zn) on White clover (Trifolium repens L. ) growth in an above-referenced multi-metal contaminated site in the absence and presence of zeolite as an agent empowering the rehabilitation of pollution and immobilization of heavy metals. Results: We demonstrated that White clover in soils with high heavy metal concentrations of Pb: 291, Cd: 4.3 and Zn: 1458 mg/kg soil acts as a “moderate” accumulator of Zn, Cd and “weak” accumulator of Pb (Fig. 1). The addition of 1% zeolite to the contaminated soils significantly contributed to plant growth by limiting the availability of Cd, Pb and Zn (Fig. 2), whilst the dry biomass of plants grown in the presence of zeolite was evaluated and found to be unsuitable as a raw material (feed) in livestock production. Conclusions: This study showed that contaminated soils must be evaluated for the necessary actions required for agricultural production. References: 1. Giannakopoulos, E. et al. (2005) J. Phys. Chem. A 109, 2223-2232. 2. Zhuang, P. et al. (2007) Water Air Soil Poll. 184, 235-242. 3. Prasad, R. et al. (2014) Afr. J. Biotechnol. 13, 705–713. 4. Ahmed, O.H. et al. (2010) Int. J. Phys. Sci. 5, 2393-2401. 5. Keller, C. et al. (2005) Plant Soil, 276, 69–84.