柠檬酸辅助甜高粱对南方典型母质土壤的镉修复效应

甜高粱生物量大,镉（Cd）吸收能力强,具有植物修复Cd污染土壤的潜力.为研究柠檬酸辅助甜高粱对南方典型母质土壤的Cd修复效应,在湖南省2种典型成土母质（中性紫泥田和黄麻砂泥田）Cd污染农田,开展甜高粱植物修复田间试验.结果表明：①柠檬酸对甜高粱生长无抑制,施用柠檬酸后甜高粱成熟期地上部生物量均呈现增大趋势,增幅为10.1%~24.7%；②甜高粱种植和柠檬酸施用降低了土壤pH值,其中柠檬酸施用进一步降低甜高粱各生育期土壤pH值,且在中性紫泥田降幅更大,降低了0.24~0.72个单位；③甜高粱种植和柠檬酸施用降低了土壤Cd总量,中性紫泥田和黄麻砂泥田降幅分别为23.8%~52.2%和17.1%~31.8%,并同时增大两地土壤Cd酸可提取态占比38.6%~147.7%和4.8%~22.7%；④柠檬酸施用显著提高甜高粱各部位Cd含量,中性紫泥田甜高粱茎和叶ω（Cd）分别为0.25~1.90 mg·kg^-1和0.21~0.64 mg·kg^-1,均高于黄麻砂泥田；⑤施用柠檬酸后中性紫泥田甜高粱成熟期地上部Cd提取量可达47.56 g·hm^-2.综上,柠檬酸可强化甜高粱修复Cd污染土壤效率,在中性紫泥田上效果更好,该技术具有重金属污染农田的边生产边修复潜力.

Cadmium Phytoremediation Effect of Sweet Sorghum Assisted with Citric Acid on Typical Parent Soil in Southern China

Sweet sorghum has a large biomass and strong cadmium (Cd) absorption capacity, which has the potential for phytoremediation of Cd-contaminated soil. In order to study the Cd phytoremediation effect of sweet sorghum assisted with citric acid on the typical parent materials in southern China, a field experiment was carried out in two typical parent material farmland areas (neutral purple mud field and jute sand mud field) with Cd pollution in Hunan Province. The results showed that:① Citric acid had no inhibitory effect on the growth of sweet sorghum. After the application of citric acid, the aboveground biomass of sweet sorghum at the maturity stage increased by 10.1%-24.7%. ② Both sweet sorghum planting and citric acid application reduced the soil pH value, and the application of citric acid further reduced the soil pH value at each growth stage of sweet sorghum; this decrease was greater in the neutral purple mud field, which decreased by 0.24-0.72 units. ③ Both sweet sorghum planting and citric acid application reduced the total amount of soil Cd, and the decreases in the neutral purple mud field and jute sand mud field were 23.8%-52.2% and 17.1%-31.8%, respectively. The acid-extractable percentage of soil Cd in both places increased by 38.6%-147.7% and 4.8%-22.7%, respectively. ④ The application of citric acid could significantly increase the Cd content in various tissues of sweet sorghum. The Cd content in the aboveground part of the plant in the neutral purple mud field was higher than that in the jute sand mud field, and the Cd content in stems and leaves was 0.25-1.90 mg·kg^-1 and 0.21-0.64 mg·kg^-1, respectively. ⑤ After applying citric acid, the Cd extraction amount of sweet sorghum in neutral purple mud soil in the mature stage reached 47.56 g·hm^-2. In summary, citric acid could enhance the efficiency of sweet sorghum in the phytoremediation of Cd-contaminated soil, and the effect was better in neutral purple mud fields. This technology has the potential for remediation coupled with agro-production for heavy metal-contaminated farmland.