基于根伸长测试终点的小白菜Cd及Se-Cd物种敏感性分布

Pai-Tsai(Brassica Chinensis L.)Species Sensitivity Distributions by Cd and Se-Cd Based on Root Elongation

暴露剂量-效应是污染物生态风险评价的核心,为了探究Se(硒)对Cd(镉)毒性的影响并筛选出小白菜Cd耐性品种,在实验室条件下,以小白菜种子萌发期的根伸长作为测试终点,采用Log-logistic模型及低剂量Hormesis兴奋效应模型确定了Cd及Se-Cd联合作用下小白菜Cd剂量-效应关系,基于Burr-Ⅲ分布模型分析了11种小白菜Cd敏感性差异.结果表明:①小白菜品种YDE(油冬儿)、HYG(黑油冠)、SZQ(苏州青)为Cd耐性品种,NY(奶油)、SG259(苏冠259)、KR(抗热)为Cd敏感性品种.②1 mg/L及以下的Cd浓度对耐性品种小白菜具有轻微的相对根伸长(RRE,relative root elongation)兴奋效应,大于1 mg/L的Cd浓度抑制其RRE;适宜浓度Se(0.6 mg/L)可有效降低5~10 mg/L浓度Cd对小白菜尤其Cd敏感性品种的毒性,但可增强高浓度Cd对多数小白菜品种的毒性.③Se-Cd作用下的HC_(5)^(20)和HC_(5)^(50)值(分别基于20%、50%Cd比例效应浓度计算得到的保护95%小白菜品种的Cd毒性阈值)分别为12.00、16.28 mg/L,分别为Cd作用下的4.0和1.4倍.研究显示,不同小白菜品种的Cd敏感性差异明显,Se对小白菜Cd毒性影响具有双重效应,适宜浓度Se能显著提高保护95%小白菜品种的Cd毒性阈值.

Exposure dose-effect is the core of ecological risk evaluation of pollutants.Taking root elongation during seed germination as test endpoint,the dose-effect relationship of Pai-Tsai(Brassica Chinensis L.)in response to Cd(cadmium)and Se(selenium)-Cd was determined using the Log-Logistic model and low-dose stimulation Hormesis model.Eleven Pai-Tsai differences in Cd sensitivity were analyzed based on the Burr Ⅲ distribution model in order to explore the effect of Se on Cd toxicity and to screen out Cd tolerant cultivars of Pai-Tsai.The results showed that the cultivars YDE(Youdonger),HYG(Heiyouguan)and SZQ(Suzhouqing)were Cd tolerant,and NY(Naiyou),SG259(Suguan),and KR(Kangre)were Cd sensitive.Cd concentrations of 1 mg/L and below had a slight excitatory effect on RRE(relative root elongation)of the tolerant cultivar,while Cd concentrations higher than 1 mg/L inhibited the RRE.Appropriate concentration of Se(0.6 mg/L)effectively reduced the toxicity of Cd at a concentration of 5-10 mg/L,especially for Cd sensitive cultivars,but it could enhance the toxicity of high concentrations of Cd to most cultivars.HC_(5)^(20)(12.00 mg/L)and HC_(5)^(50)(16.28 mg/L)under the Se-Cd were 4.0 and 1.4 times that under the Cd,respectively.In summary,this study revealed that the Cd sensitivities varied significantly among different Pai-Tsai cultivars,Se had a dual effect on the Cd toxic effect of Pai-Tsai,and appropriate Se concentration significantly increased the Cd toxicity threshold of 95%of Pai-Tsai cultivars.These findings can provide a reference for determining the toxicity threshold of Cd in Pai-Tsai cultivation environment and ecological risk evaluation under Se-Cd.