Effects of inorganic and organic amendments on physiological parameters and antioxidant enzymes activities in Zea mays L. from a cadmium-contaminated calcareous soil

Abstract

In situ stabilization is a promising remediation technology to decrease the hazard potential of contaminants in soils through converting them into their least-soluble, -mobile or -toxic forms. In the present study, the effectiveness of various amendments (e.g., biochar 640 °C, and biochar 420 °C) and selected low cost amendments (e.g., leca, pumice, bentonite, and zeolite) was investigated on Cd stabilization through testing their potential to decrease soil Cd bioavailability, and their effects on photosynthetic pigments, antioxidant enzyme activities and Cd uptake by maize (zea mays L.) in a polluted calcareous soil. By the end of the experiment, all amendments resulted in increased soil pH value and electrical conductivity (EC) relative to the control soil. The Toxicity Characteristic Leaching Procedure (TCLP) Cd was supposed to indicate the potential bioavailability of Cd in the soils. Generally, application of the amendments decreased the Cd bioavailability in the soils compared to un-amended soil. This decreased bioavailability of Cd in soil was accompanied by an increased antioxidant enzyme activities and photosynthetic pigments, and decreased plant uptake of Cd. Plant antioxidant enzyme activities {superoxide dismutase (SOD), catalase (CAT), peroxidase (PX), and ascorbate peroxidase (ASP)} and photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids) were significantly increased in the amended soils. These increases may be due to a lower Cd accumulation in leaves. Zeolitse (%5) was the most effective amendment in decreasing cadmium concentration in maize.