Alleviation of Cd stress in maize by compost mixed biochar

Abstract

Cadmium (Cd) is a heavy metal that neutrally occurs in soil. It is carcinogenic in humans and caused a significant decline in the plant’s growth when up has taken beyond the threshold limit. The fertilizers, manure, sewage sludge, and aerial deposition are the main source of cadmium contamination in soil. Furthermore, poor soil organic matter is also one of the allied factors which facilitate the development of Cd toxicity in soil. The decomposition resistance nature of biochar makes it an effective amendment for cadmium remediation. Through crop production, Cd enters the food system. Individual studies on biochar and compost are found in the literature but the combined effect of biochar and compost are rarely documented especially in maize crops. The current pot study was conducted in Pesticide Quality Control Laboratory, Multan, Pakistan. However, the current study was novel and conducted by using compost mixed biochar (CB) against Cd toxicity in maize. Four application rates of CB i.e., 0, 0.50, 0.75 and 1.00% (1.00CB) were applied under 3 levels of Cd i.e., 0 (0Cd), 2.5 (2.5Cd) and 5 mg Cd kg−1 soil (5.0Cd). Overall, results indicated that 1.00%CB remained significantly best at higher 5.0Cd for improvement in soil organic matter, plant height, root length, number of leaves, leaves fresh and dry weight, plant fresh and dry weight, chlorophyll a, b, total and carotenoids. A significant decrease in soil pHs, leaves anthocyanin and lycopene also validated the efficacious functioning of 1.00%CB over control in 2.5 and 5.0Cd. In conclusion, the use of 1.00%CB is a better approach to decrease Cd harmful effects to improve gas exchange attributes, growth and chlorophyll contents in maize. Long-term research is required on co-composted biochar toward mitigation of cadmium toxicity under different geographical locations.

Keywords

• Chlorophyll contents
• Heavy metals
• Zea mays L.
• Organic amendments
• Photosynthetic rate
• Stomatal conductance