A multivariate analysis of physiological and antioxidant responses and health hazards of wheat under cadmium and lead stress

Soil contamination with heavy metals is a global issue confronting the environmental pollution and human/animal health. Much work has been done on physiological and antioxidant responses of wheat in hydroponic experiments and health risks from individual heavy metal contamination to human, but limited information is available on their combined application in soil. Therefore, this pot study delineates the uptake of lead and cadmium, as well as physiological responses of wheat and associated health risks under different levels of alone and combined Cd and Pb treatments. Metal uptake increased with their increasing applied levels. The highest Cd (4.24, 1.38, and 0.92mgkg(-1)) and Pb (763.33, 39.63, and 16.35mgkg(-1)) concentrations in root, shoot, and grain, respectively, were observed at highest applied levels (0.4mM Cd and 10mM Pb). Furthermore, all the treatments increased lipid peroxidation and activities of superoxide dismutase, catalase, ascorbate peroxidase, and peroxidase, while decreased total chlorophyll contents and membrane stability index. Under combined application of Cd and Pb, the toxicity and detoxification responses of wheat increased compared to alone treatments. Multivariate analysis further confirmed the toxicity and accumulation pattern of metals under alone and combined treatments. Target hazard quotient values of Cd and Pb were <1 under alone and combined treatments. The health hazard index values of Pb (97.07 and 87.89%) were higher than those of Cd (2.93 and 12.10%) in combined application for human and buffalo, respectively. This study highlights that the multi-metal contamination (Cd and Pb) is detrimental for wheat growth and human/animal health.