Pressmud Alleviates Cadmium Stress in Wheat by Enhancing Soil Microbial Activity, Nutrient Uptake and Limiting Cd Accumulation
摘要
Soil contamination with cadmium (Cd) poses a serious threat to wheat production by impairing soil biological health and reducing grain quality. Organic materials such as pressmud may mitigate metal-induced stress to wheat by restoring soil microbial activities, improving nutrient uptake and limiting Cd absorption from soil. In this study, a pot experiment was conducted using salt-affected sandy loam soil spiked with Cd at 0, 25 and 50 mg kg⁻1. After two weeks, pressmud was applied to soil at 0, 10 and 20 g kg⁻1, and wheat was sown. Plants were harvested at the seedling stage and at maturity to assess soil biological activity, plant antioxidants, growth, yield and grain Cd accumulation. Cadmium contamination significantly suppressed soil biological activity, reducing soil respiration by 6–19%, microbial counts by 25–37%, dehydrogenase activity by 10–30%, phosphatase activity by 7–19% and urease activity by 25–37% compared with the control. In response to Cd stress, plants exhibited higher levels of antioxidants (SOD, POD, and CAT), indicating stress to plants. However, Cd caused sharp reductions in shoot biomass (18–33%) and grain yield (23–25%), along with decreased nutrient uptake. Cadmium accumulation in grains increased with the soil Cd levels. The application of pressmud alleviated these adverse effects by sustaining soil microbial populations and enzyme activities under Cd stress. Pressmud-treated plants showed lower antioxidant enzyme activity—indicating reduced oxidative stress—along with improved growth, higher yields, greater nutrient uptake and lower grain Cd accumulation. Overall, pressmud is an effective organic amendment for mitigating Cd toxicity, thereby enhancing wheat productivity and grain quality.