Differential growth and metal accumulation response of castor bean genotypes on a lead contaminated soil

Abstract

Abstract In Pakistan, probably thousands of hectares are contaminated with heavy metals. As castor plant is hyper-accumulator of heavy metals, its cultivation in the area of lead (Pb) contamination can show great potential in terms of remediation of soils. Present study aimed to evaluate the phytoremediation potential of different castor genotypes, NIAB Gold, NIAB Spineless, NIAB-2020, DS-30 and C-3 grown in pots filled with 5 kg soil, spiked with various concentrations of Pb (0, 100, 200, 400, and 800 mg kg− 1). Results showed that plant biomass and photosynthetic pigments reduced significantly with increasing Pb concentrations. Activities of superoxide dismutase and peroxidase were decreased significantly whereas catalase and ascorbate peroxidase were increased with increasing Pb levels in all genotypes. At 800 mg Pb kg− 1 soil, the highest catalase and ascorbate peroxidase activities of 12.23 and 64.43 mM/g FW, respectively, were recorded in DS-30 followed by NIAB-2020. The highest total soluble proteins (8.44 mg g− 1) were recorded in DS-30 followed by NIAB-2020 under Pb contamination at 800 mg kg− 1 soil. Lead uptake increased significantly with increasing levels of Pb and highest uptake in roots were recorded in NIAB-2020 (302 mg kg− 1) followed by DS-30 (299 mg kg− 1) under Pb contamination at 800 mg kg− 1. All genotypes showed metal translocation factor less than 1 under all Pb levels. In conclusion, NIAB-2020 and DS-30 possessed good potential with better Pb accumulation, osmolytes production and antioxidant activities compared to other castor bean genotypes.