[Effects of the Immobilization of Cadmium in Soil Alone or Combined with Foliar Application of Selenium on Cadmium Accumulation in the Plants of Different Genotypes of Tsai-tai].

To explore the safe utilization of technology in mildly and moderately cadmium (Cd)-contaminated farmland and realize the safe production of agricultural products, two different cadmium-accumulating genotypes of Tsai-tai were used as test crops, using the pot experiment method. The same six treatments were set on the soil where the two test crops were planted:control (CK), addition of 3% (mass fraction) biochar (BC), addition of 0.17% calcium magnesium phosphate fertilizers (CMP), foliar application of 3 mg·L NaSeO aqueous solution (Se), BC+Se, and CMP+Se, to study the changes in available cadmium in soil under different treatments and the characteristics of cadmium accumulation in different parts of the plant. The results showed that:① Under the same treatment, the content of available cadmium in soil near the root of the low-cadmium-accumulating genotype of Tsai-tai of Jinqiuhong Ⅲ was significantly lower than that of the high-cadmium-accumulating genotype of Shiyuehong. BC and CMP had a significant passivating effect on cadmium in the soil near the root of Jinqiuhong Ⅲ, and the passivating effect of BC was better than that of CMP; the effect of passivating treatment was significantly better than that of foliar application of selenium. ② The root system of Tsai-tai of Jinqiuhong Ⅲ had a stronger ability to accumulate cadmium than that of Shiyuehong, and the accumulated cadmium tended to be stored in the root. There were no synergistic effects between the foliar application of selenium and the two kinds of passivants on inhibiting the transfer and enrichment of cadmium to the edible parts of Tsai-tai. ③ Under the treatments of BC and CMP, the content of cadmium in the edible part of Tsai-tai of Jinqiuhong Ⅲ was lower than the limit value of cadmium in GB 2762-2017 (0.10 mg·kg). This study shows that for mildly and moderately cadmium-contaminated farmland, applying green passivants such as biochar, calcium magnesium phosphate fertilizers, and planting crops with weak absorption and low accumulation can achieve the safe use of the cadmium-contaminated farmland and safe production of agricultural products.