Heavy metal phyto-accretion, biochemical responses and non-carcinogenic human health risks of genetically diverse wheat genotypes cultivated with sewage of municipal origin

Abstract

Current study explored the effects of municipal sewage (MS) irrigation on heavy metal phyto-accretion, biochemical responses and human health risks of diverse wheat genotypes along with recycled municipal sewage (RMS). Mean concentrations of PO₄^3-, NO₃^--N, chemical oxygen demand, biological oxygen demand, K, Co, Cu, Cd, Cr and Ni were found higher in MS than irrigation criteria. This led to significant increase in heavy metal contents in roots, stem and grains of MS irrigated wheat genotypes compared to RMS and control treatments. No adverse health risk effects for individual or multiple metals were recorded in RMS irrigated wheat genotypes on grounds of lowest heavy metal accumulation. Multivariate techniques i.e. principal component analyses (PCA) and hierarchical agglomerative cluster analyses (HACA) identified tolerant (inefficient metal accumulators) and sensitive (efficient metal accumulators) wheat genotypes in MS and RMS. Tolerant wheat genotypes showed lowest accumulation of heavy metals, efficient biochemical mechanisms to combat oxidative stress and lower health risks to adults/children. Cultivation of identified tolerant wheat genotypes is recommended in areas receiving municipal wastes to reduce human and environmental health risks. Moreover, genetic potential of identified tolerant wheat genotypes from MS and RMS can be utilized in breeding heavy metal tolerant wheat germplasm worldwide.

Keywords:

• Heavy metals
• human health risks
• multivariate techniques
• municipal sewage
• wheat genotypes

Acknowledgments

Authors thankfully acknowledge the Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan for the provision of metal analytical facilities.