Contamination of chromium signifies one of the major threats to soil system. Phytoremediation is a promising technique to reclaim metal-contaminated soil using plants which are capable to tolerate and accumulate heavy metals within in their tissues. The experiment reported in this article was carried out with six biofuel plant species, Cyamopsis tetragonoloba, Glycine max, Avena sativa, Abelmoschus esculentus, Sesamum indicum and Guizotia abyssinica, were subjected to eight Cr concentrations (0.5, 2.5, 5, 10, 25, 50, 75 and 100 mg kg⁻¹ soil) to investigate Cr toxicity, tolerance and accumulation. After 12 weeks of experiment, Cr phytotoxicity on morphological and biochemical parameters were evaluated. For six plant species, seed germination and most of growth parameters were significantly (p < 0.05) reduced under high Cr stress. Chlorophyll contents were also decreased with increased Cr concentrations. Accumulation of Cr was higher in roots than shoot in all studied plants. Significant Cr accumulation was in the order of C. tetragonoloba > A. sativa > A. esculentus > S. indicum > G. max > G. abyssinica. Bioconcentration factor, bioaccumulation coefficient, translocation factor and phytoremdiation ratio suggested that C. tetragonoloba, A. sativa and A. esculentus being more tolerant; having higher Cr accumulation and could be a high efficient plants for reclamation of Cr-contaminated soils.

Phytoextraction involved the use of plants in rapid, efficient, less expensive, and environment friendly removal of toxic metals from contaminated soil. For this study, a pot experiment was conducted and plant species: Abelmoschus esculentus, Avena sativa, Guizotia abyssinica, and Glycine max were subjected to six copper concentrations i.e., 25, 50, 100, 150, 200, and 300 mg Cu kg⁻¹ for the investigation of Cu phytotoxicity, tolerance, and accumulation for 12 weeks under green house. Soil without spike were taken as control. After 12 weeks of experiment, Cu toxicity on growth and chlorophyll contents were determined. Among four plant species, only A. sativa, C. tetragonoloba and S. indicum seeds were germinated at 300 mg Cu kg⁻¹. The growth parameters were significantly (p < 0.05) reduced under high Cu stress (from 25 to 100 mg Cu kg⁻¹) in G. abyssinica and G. max. The chlorophyll content found maximum at 25 mg Cu kg⁻¹ in all plant species as compared to control. Significantly, high Cu accumulation was found in roots and shoots of A. sativa. The highest values of bioconcentration factor, bioaccumulation coefficient, translocation factor (all greater than 1), phytoremediation ratios, and accumulation with high tolerance suggested that A. sativa was a suitable plant for effective Cu phytoextraction.

Phytoextraction is a plant-based technique for removing heavy metals from polluted soil. The experiment reported in this paper was undertaken to study the Zn phytoextraction potential of Cyamopsis tetragonoloba in comparison with Sesamum indicum in the framework of a pot experiment. Plants were subjected to six Zn concentrations (0, 50, 100, 200, 300, 400 mg kg⁻¹ soil) for 90 days to investigate Zn tolerance and accumulation. Results demonstrated that, at higher Zn levels, root, shoot lengths, biomass and chlorophyll content were all significantly reduced (p < 0.05). A steady increase in Zn accumulation with increasing concentration in soil was observed for all treatments. Both plant species had relatively high Zn tolerance and accumulation capacity, with C. tetragonoloba being more tolerant and having higher Zn accumulation than S. indicum. At 400 mg Zn kg kg⁻¹, accumulation of Zn in C. tetragonoloba was highest in the root (439.33 mg kg⁻¹) followed by stem (436.00 mg kg⁻¹), leaf (40.67 mg kg⁻¹) and pod (11.33 mg kg⁻¹). Considering the rapid growth, high biomass, tolerance, accumulation efficiency, bioconcentration factor (BCF), bioaccumulation coefficient (BAC) and translocation factor (TF) (all greater than 1) established C. tetragonoloba as a potential candidate plant for Zn phytoextraction.