不同镉浓度下水稻和小麦生长、籽粒镉吸收特征及土壤镉临界值研究

Growth and Grain Cadmium Absorption Characteristics of Rice and Wheat under Different Cadmium Concentrations and Soil Cadmium Critical Value

    摘要
  • 摘要:
    目的 为了探讨不同镉（Cd）浓度对四川地区不同土壤pH值的农田土壤上水稻和小麦生长以及籽粒中Cd吸收的影响。
    方法 采集了四川地区黄红壤、潮土和酸性紫色土三种典型农用地0 ~ 20 cm耕作层的土样，并向样品中添加了0 ~ 10.00 mg kg−1外源Cd。通过盆栽试验分析了土壤与水稻、小麦生长以及籽粒中Cd吸收量之间的关系。在确保水稻和小麦籽粒中Cd含量符合食品安全国家标准污染物限值的前提下，初步评估了3种水稻和小麦产地土壤中Cd的安全临界值。
    结果 随着外源Cd浓度的逐渐升高，水稻和小麦的株高、茎秆干重以及籽粒干重整体上均呈现出先增长后减弱的趋势。与此同时，Cd浓度的提升也导致叶片的SPAD值有所降低，而茎秆与籽粒中的Cd吸收量则显著增加。根据食品安全国家标准污染物限值，水稻和小麦所种植的黄红壤、潮土和酸性紫色土三种土壤的总Cd临界值范围分别为0.57 ~ 2.74 mg kg−1和0.06 ~ 0.40 mg kg−1，有效Cd临界值范围分别为0.08 ~ 0.19 mg kg−1和0.01 ~ 0.03 mg kg−1。
    结论 种植水稻的三种土壤以及种植小麦的黄红壤，其总Cd临界值均高于现行的风险筛选值（GB15618－2018）。其中黄红壤的总Cd临界值最高，酸性紫色土次之，潮土最低。此外，土壤的Cd临界值与土壤的pH值及有机质含量之间呈现出显著的正相关关系。

     

    Abstract: :
    Objective The aim was to investigate the effects of different cadmium (Cd) concentrations on the growth of rice and wheat and the absorption of Cd in grain in different pH values of soil in Sichuan.
    Method Soil samples from the 0 ~ 20 cm of cultivated land in three typical agricultural lands in Sichuan were collected: Yellow-red soil, fluvo-aquic soil and acidic purple soil, and 0 ~ 10.00 mg kg−1 exogenous Cd was added to the samples. The relationship between soil and the growth of rice and wheat and the absorption of Cd in grain was analyzed by pot experiment. On the premise of ensuring that the content of Cd in rice and wheat grains meets the pollutant limits of national food safety standards, the safety critical values of Cd in soil of three rice and wheat producing areas were evaluated.
    Result The results showed that the plant height, stem dry weight and grain dry weight of rice and wheat showed a trend of first increase and then decrease with the gradual increase of exogenous Cd concentration. At the same time, the increase of Cd concentration also resulted in the decrease of SPAD value in leaves, while the Cd uptake in stems and grains increased significantly. According to the pollutant limits of the national standard for food safety, the critical values of total Cd in the three soils of yellow-red soil, fluvo-aquic soil and acidic purple soil planted by rice and wheat were 0.57 ~ 2.74 mg kg−1 and 0.06 ~ 0.40 mg kg−1, respectively. The critical values of effective Cd ranged from 0.08 ~ 0.19 mg kg−1 and from 0.01 ~ 0.03 mg kg−1, respectively.
    Conclusion The study showed that the critical value of total Cd in the three soils planted in rice and the yellow-red soil planted in wheat was higher than the current risk screening value (GB15618-2018). Among them, yellow-red soil had a higher Cd critical value, followed by acidic purple soil, and fluvo-aquic soil had the lowest value. In addition, the critical value of soil Cd exhibited a positive correlation with soil pH and the content of organic matter.

     

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