生物炭和锌对土壤镉赋存形态及小麦镉积累的影响

为探讨生物炭单独施用及其联合锌施用对镉污染土壤安全利用的可行性，采用污灌区镉污染土壤种植小麦盆栽试验，结合小麦生长参数、抗氧化酶活性、相关基因表达，研究单独施用0、1.0%、1.5%和2.0%小麦秸秆生物炭以及与锌混施(在上述4个处理组土壤中施加30 mg/kg七水合硫酸锌)对镉胁迫下土壤镉形态特征和小麦镉积累特征的影响. 结果表明:①施用生物炭可促使土壤可交换态、碳酸盐结合态向稳定性强的有机结合态和残渣态转化，且随着生物炭施用量的增加，转化比例显著增加，但锌施用对土壤镉形态没有显著影响. ②土壤施加1%~2%生物炭能够显著降低小麦籽粒镉含量29%~57%，且施用2%生物炭可将籽粒镉含量降至0.1 mg/kg以下，土壤同时施用生物炭和锌可在单施生物炭基础上降低籽粒镉含量21%~39%，具有协同效应. ③施用生物炭和锌均可促进植物生长，提高小麦产量，并通过调节小麦丙二醛(MDA)和抗氧化酶(SOD、POD和CAT)活性提升小麦根系细胞抗氧化能力，以及调节镉转运基因(TaNramp5、TaLCT1、TaHMA3和TaHMA2)的表达，降低小麦根系从土壤吸收镉以及向地上部分转运，从而减少小麦对镉的吸收和积累. 研究显示，向土壤添加生物炭和锌对污灌区小麦的安全生产具有参考和指导意义. 

Effects of Biochar and Zinc on Soil Cadmium Fractions and Wheat Accumulation

In order to study the application effect of only biochar and biochar combined with zinc on the remediation of cadmium (Cd)-contaminated soils, Cd-contaminated soil was collected from sewage irrigation area and used to cultivate wheat in a pot experiment. Combined with wheat growth parameters, antioxidant enzyme activities, and related gene expression, the soil Cd fraction and accumulation in wheat were studied under the Cd stress with the only wheat-stem biochar application at the rate of 0, 1.0%, 1.5%, and 2.0%. Besides only biochar application, combined application of zinc (Zn) with 30 mg/kg Zn sulfate heptahydrate was applied to the above four treatments. The results showed that biochar application can promote the soil exchange and carbonate-bounded Cd fraction transformation to organic-bounded and residual fractions, and the transformation rate increased with the increase of the amount of added. However, Zn application had no impact on the soil Cd fraction. The application of 1%-2% biochar significantly reduced grain Cd concentration by 29%-57%, and the grain Cd concentration was reduced to 0.1 mg/kg by the application of 2%. The grain Cd concentration was reduced by 21%-39% by only biochar application. Soil zinc and biochar application had a synergistic effect. The application of biochar and zinc can promote plant growth, improve wheat yield, and improve the antioxidant capacity of wheat root cells by regulating the activities of MDA and antioxidant enzymes (SOD, POD and CAT). The application can also regulate the expression of Cd transporter genes (TANRAMP5, TALCT1, TAHMA3 and TAHMA2) to reduce the soil Cd uptake and transport root Cd to the above ground parts, thus reducing the uptake and accumulation of Cd in wheat plants. Therefore, soil application of biochar and zinc has practical reference and guiding significance for the safe production of wheat in wastewater irrigation areas.