不同种植年限粉葛对农田土壤镉的富集特征

为揭示不同种植年限粉葛对土壤重金属镉的富集特征，以江西新余中度镉污染农田种植的一年生、两年生粉葛为研究对象，分析不同种植年限间粉葛（Pueraria thomsonii Benth）块根（葛粉和葛渣）、葛头、主藤、侧枝和叶片中重金属镉的含量及其富集情况。结果表明，除叶片外，两年生粉葛各部位镉含量显著高于一年生的；粉葛不同部位镉含量大小排序为侧枝>主藤>葛头>叶片>葛渣>块根>葛粉；粉葛对土壤镉富集系数均>1，说明粉葛对土壤中镉的吸收能力较强。除一年生粉葛葛粉外，一年生粉葛块根和两年生粉葛块根、葛粉中镉含量均超过国家食品安全限量标准。相关分析表明，粉葛各部位镉含量与土壤总镉和有效态镉含量呈显著正相关，粉葛各部分中镉含量随种植年限具有明显的累积效应。因此，在中度镉污染农田宜选择种植一年生粉葛，且食用方式以葛粉最佳，以达到生态和经济效益双赢。

Enrichment of cadmium by Pueraria thomsonii Benth planted for different years in farmland

An attempt was made to reveal the cadmium enrichment characteristics of Pueraria thomsonii planted for different years. The plants of P. thomsonii grown for one year and two years on moderately cadmium-contaminated farmland in Xinyu, Jiangxi province were collected to determine the content and enrichment of the heavy metal cadmium in the tuber (meal and residues), basal stem, main stem, lateral branches, and leaves. Except for the leaves, the cadmium content was significantly higher in each part of the two years old plants than in the one year old plants. The contents of cadmium in different plant parts were in the order of lateral branch > main stem > basal stem > leaves > residues > tuber > meal. P. thomsonii has a high capacity to absorb cadmium from soil, as evidenced by the enrichment coefficient of cadmium from soil to P. thomsonii being larger than 1. Except for the meal of the tuber from the one year old plants of P. thomsonii, the cadmium contents in the tuber of 1-years old plants, and the tuber and meal of 2-years old plants were all higher than the limit of the standard. Correlation analysis showed that the content of cadmium in each part of P. thomsonii had a significantly positive correlation with the total and available cadmium in the soil and had an accumulative effect on the age of the plants. Therefore, in a moderately cadmium-contaminated farmland it is recommended to plant P. thomsonii for one year and use its tuber to produce meal as food to attain both ecological and economic benefits.