Phytoremediation of soil cadmium using Chenopodium species

Phytoremediation is effectively used to remove heavy metals from soil. In this research Chenopodium album and Chenopodium murale were evaluated for their comparative potential to phytoremediate increased (0-750 μM) cadmium (Cd) from soil. Both the Chenopodium species showed wide difference for Cd tolerance. Chlorophyll (Chl) a was at par with control in at 250 μM Cd C. album, but was reduced in C. murale. Chl b was less reduced by Cd in C. album than in C. murale resulting in an increased Chl a:b ratio. Likewise, carotenoids were reduced minimally in C. album and greatly in C. murale. Although soluble phenolics were reduced in both the species, a markedly greater accumulation of anthocyanins was noted in C. album at all Cd levels. Greater levels of Chl a and anthocyanins and minimal Chl b contents were important to Cd tolerance in C. album. The C. album showed a minimal reduction in K⁺, steadier Ca²⁺, SO₄^2--S, and PO₄^3- in shoot and root, NO₃^- in the shoot. C. album accumulated more Cd in shoot while C. murale in root, and showed greater capacity to adjust metabolites and accumulate macronutrients. From the increased shoot Cd contents, whilst showing better growth, we infer that metabolic changes could help bind and sequester excess of Cd in the vacuole, and thus better Cd tolerance. Greater seed germination, reduced post-germination mortality and enhanced growth of mungbean (used as successive crop) substantiated that C. album is a better phytoremediator of Cd than C. murale. In crux, better growth and Cd-phytoremediation by C. album may have great implications for agricultural practices.