| To explore the immobilization effect of amendments on cadmium (Cd) contaminated soil and inhibitory effect on Cd uptake by garlic seedlings, both calcareous and acidic cadmium-contaminated soils were selected in this study for pot experiments. The effects of thiol-modified compound, zeolite, phosphate modified biochar and lime on soil Cd availability, chemical forms, antioxidant enzyme activity, and Cd uptake by seedlings were investigated. Furthermore, high-throughput sequencing technology was employed to determine the bacterial community structure in the soil. The results indicated that application of amendments reduced soil available Cd in comparison with the control. Specifically, the application of 12 g·kg?1 modified biochar in calcareous soil and 2 g·kg?1 lime in acidic soil demonstrated the optimal immobilization effects on cadmium, with available cadmium contents decreasing by 46.4% and 52.9%, respectively. Further analysis for Cd chemical forms revealed that amendments could promote the transformation of soil Cd from weakly acidic extractable and reducible states to oxidizable and residual states. Moreover, the amendments also inhibited the absorption of Cd by seedlings, the maximum reduction in Cd content in shoots could reach 51.7% and 73.8% in calcareous and acidic soils, respectively. While values for roots were 31.3% and 74.7%, respectively. Among them, the thiol-modified compound showed the best effect in calcareous soil, while the effect of lime was superior in acidic soil. Additionally, the application of amendments enhanced the activity of antioxidant enzymes (SOD, POD, CAT) and reduce MDA content, thereby alleviating Cd stress to seedlings. In calcareous soil, thiol-modified compound and zeolite significantly increased the abundance of Arthrobacter; while in acidic soil, thiol-modified compounds increased the abundance of Bacillus, while modified biochar and lime increased the abundance of Pseudomonas. In conclusion, amendments studied could reduce the bioavailability of soil Cd, improve soil bacterial community structure, and inhibit the absorption and accumulation of Cd by garlic seedlings. |
