Assessment of cadmium and lead tolerance potential of quinoa (Chenopodium quinoa Willd) and its implications for phytoremediation and human health.

Soil contamination with Cd and Pb is a worldwide problem which not only degrades the environment but also poses a serious threat for human and animal health. Phytoremediation of these contaminated soils using halophytic plants like quinoa presents an opportunity to clean the soils and use them for crop production. The current experiment was performed to evaluate the Cd and Pb tolerance potential of quinoa and subsequently its implications for human health. Three weeks old quinoa seedlings were exposed to Cd (30, 60 and 90 mg kg-1) and Pb (50, 100 and 150 mg kg-1) levels along with a control. The results revealed that plant height decreased at highest levels of soil Cd and Pb. Shoot, root and seed dry weight decreased with increasing levels of soil Cd and Pb. Tissue Cd and Pb concentrations increased with increasing levels of Cd and Pb in soil, the highest Cd was found in roots while the lowest in seeds. The highest Pb concentration was found in shoots at low Pb level, while in roots at high level of Pb. Increasing levels of Cd and Pb stimulated the activities of measured antioxidant enzymes and decreased membrane stability index. The health risk assessments of Cd and Pb revealed that hazard quotient was < 1 for both the metals. However, the results of total hazard quotient showed that value was < 1 for Pb and 1.19 for Cd showing potential carcinogenicity. This study demonstrates that quinoa has good phytoremediation potential for Cd and Pb however, the risk of Cd toxicity is challenging for human health.

Comparative effect of organic amendments on physio-biochemical traits of young and old bean leaves grown under cadmium stress: a multivariate analysis.

The current study investigated the influence of organic amendments on cadmium (Cd) uptake and its effects on biochemical attributes of young and old leaves of bean. Bean seedlings were exposed to two levels of Cd (25 and 100 µM) in the presence and absence of different levels of ethylenediaminetetraacetic acid (EDTA) and citric acid (CA). An increase in Cd concentration in growth medium significantly enhanced Cd accumulation in bean roots and shoot. Cadmium stress increased the production of H2O2 which resulted in lipid peroxidation and decreased chlorophyll contents. The presence of organic amendments significantly affected Cd accumulation and toxicity to bean plants. Application of EDTA alleviated Cd toxicity in terms of chlorophyll contents, H2O2 contents, and lipid peroxidation possibly by chelating toxic Cd ions, and as such forming Cd-EDTA complexes. The presence of CA decreased Cd toxicity by decreasing its uptake. The biochemical responses (H2O2 contents, lipid peroxidation, and chlorophyll contents) of bean plants were more severely affected by Cd treatments in old leaves compared to young leaves. This study shows that the effect of CA and EDTA on biochemical behavior of Cd varies greatly with applied levels of Cd and amendments as well as the age of leaves. Based on the results, it is proposed that the presence of organic amendments can greatly affect biogeochemical behavior of Cd in the soil-plant system (ecosystem).