Cadmium Stress Alleviation: Interplay of Micronutrients and Enzymatic/Non-enzymatic Species in Maize by Organic and Inorganic Amendments

With the advancement in industrialization and to cope with the ever-increasing demand for food, the farmer community is compelled to use various approaches, including the excessive use of phosphatic fertilizers, irrigation with contaminated water, and limited access to alternative inputs. These practices have resulted in cadmium toxicity. The present study aimed to assess the efficacy of four organic amendments including press mud, sugar cane bagasse, humic acid, and biochar along with four inorganic amendments including gypsum, CaCl₂, iron and silicon nanoparticles in reducing the bioavailability of Cd in soil. The results revealed that the press mud treatment exhibited the highest percentage increase in growth and physiological indices, with a value of 188.63%, followed by sugarcane, humic acid, biochar, Fe, Si NPs, gypsum and CaCl₂ with a percentage increase of 162.26%, 141.65%, 93.50%, 81.13%, 71.56%, 59.24%, and 12.14%, respectively. The maximum malondialdehyde (MDA) contents were recorded in the Cd treatment, and a significant inconsistency in antioxidant enzyme activity such as catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and Proline content was observed between organic and inorganic amendment treatments. Press mud exhibited the lowest Ab-DTPA Cd value, which was 11.96% at 100 ppm, with other treatments ranging between 15.17 and 37.01%. In conclusion, applying the studied amendments demonstrated a potential to decrease Cd bioavailability in the soil, leading to improved photosynthetic pigment levels and reduced Cd uptake by maize plants. Press mud, humic acid, gypsum, and Fe-NPs were identified as particularly effective amendments for reducing cadmium concentrations by binding in soil for reduced transport to maize, alleviating toxicity, and oxidative stress management. Additional research is necessary to determine the ideal concentrations for each treatment and their overall impact on plant growth and development. Graphical Abstract: (Figure presented.)