Alleviating cadmium-induced stress in maize: the role of zinc sulphate application on growth and biochemical responses.

Cadmium stress (Cd) damages plant growth and development by causing oxidative damage and plant physiological and biochemical attributes. However, zinc sulphate (ZnS) may act as an acute stress signal to alleviate the toxic effects of Cd stress by upregulating the antioxidant defense mechanism and enhancing nutrient absorption. This study aimed to evaluate the impact of ZnS foliar application on mitigating the toxic effects of Cd stress in maize seedlings. The treatments were a) ZnS applications (0 ppm, 20 ppm, and 40 ppm), b) maize varieties, V1 = Malka-16 and V2 = Sahiwal Gold, and Cd stress (0 mg kg^-1, 20 mg kg^-1, and 40 mg kg^-1). Cadmium stress significantly reduced the growth and chlorophyll content in maize varieties as compared to the control. Results have revealed that plant growth and photosynthetic pigments were reduced under Cd stress as plant height and carotenoid contents decreased by 41.5 and 45.0% in Malka-16 and 12.7 and 50% in Sahiwal Gold compared to the control. Nutrient uptake was also significantly affected by Cd stress as calcium, phosphorus, potassium, and sodium were reduced in the roots, stems, and leaves in both maize varieties. However, ZnS treatments successfully reduced the toxicity of Cd stress in maize varieties and improved plant growth and development as compared to the control. Among the antioxidants, ascorbate (AsA), peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) were improved by 22.3, 12.8, 15.2, and 17.6% in Malka-16 and 18.0, 18.3, 16.2, and 18.8% in Sahiwal Gold by ZnS supplementations under Cd stress. Among both varieties of maize, Sahiwal Gold outperformed Malka-16 regarding plant morphophysiological, biochemical attributes, and nutrient uptake under Cd-stressed conditions. In crux, ZnS applications in maize decreased the toxicity of Cd stress by modifying the plant's antioxidant defense system. Zinc use is a promising strategy for sustainable agriculture since it enhances yield and quality and decreases cadmium deposition in edible plant parts.