【摘要】 采用对氯苯甲酸敏感的2种白菜进行种子暴露试验,研究表观性状指标与生物化学指标对3种氯苯甲酸的敏感程度,以便更加全面地反映氯苯甲酸的植物毒性和筛选能指示氯苯甲酸的敏感因子。结果表明,在3种氯苯甲酸对2种白菜根伸长10%～50%抑制区间内,氯苯甲酸剂量-发芽抑制率和氯苯甲酸剂量-根伸长抑制率均存在极显著的线性关系(P<0.01),从拟合方程的斜率可以看出,3种氯苯甲酸浓度的变化对2种白菜发芽率抑制的影响幅度大于对根伸长抑制的影响幅度。氯苯甲酸剂量-SOD(超氧化物歧化酶)活性抑制率之间和氯苯甲酸剂量-CAT(过氧化氢酶)活性抑制率之间均存在二项式关系(P<0.05),氯苯甲酸剂量-POD(过氧化物酶)活性抑制率之间存在线性关系(P<0.05)。根据拟合方程求出相应的半效应浓度(IC50),3种氯苯甲酸的SOD和CAT的半效应浓度均在试验区间之外,POD的半效应浓度则在试验区间之内,表明在试验区间内,SOD和CAT活性不敏感,POD是个有效指标,且对于3-氯苯甲酸和4-氯苯甲酸的敏感程度高于发芽率和根伸长抑制率。拟合直线方程的斜率可考虑作为“辅助性指标”去评估植物毒性,因为越大的斜率值意味着在试验过程中该指标的单位变化幅度越大,也就越容易观察。更多还原

【Abstract】 Using one kind of indicator was not sufficient to understand the phytotoxicity of organic substance comprehensivly, since the results were easily disturbed by the adverse surroundings. The indicator system composed of differentkinds of indicators could overcome the shortage. The sensitive degrees to the three chlorobenzoic acids of the apparent property indicator and the biochemical indicator were compared for providing comprehensive information on the phytotoxicity of CBA and screening the more sensitive endpoint. Two terrestrial plant species in same category, Chinese cabbage (Brassica pekinenses) and Chinese white cabbage (Brassica rapa L.Chinensis Group), were exposed to different concentrations of CBA in the germination test. There existed very significant linear correlations between CBA dose with germination inhibition rate and root elongation inhibition in the inhibition range of root elongation 10%～50%(P<0.01), and the dose differences had more influence on germination inhibition rate than on root elongation inhibition rate. The quadratic relationships between CBA dose with inhibition rate of the superoxide dismutase (SOD) activity and inhibition rate of the catalase (CAT) activity were also observed, while, the linear relationshipbetween CBA dose and inhibition rate of the perioxidase (POD) activity was significant (P<0.05). IC50 of SOD and CAT were beyond the experimental dose range, but that of POD was in the range, which suggested that the inhibition degree of POD activity, not the inhibition degree of SOD and CAT activity, was invalid indicator could be considered as an effective indicator, more sensitive than the germination rate and root elongation rate for 3-CBA and 4-CBA. Furthermore, theslope of plotting equation should be regard as "assistant endpoints" to assess the phytotoxicity, since the bigger slope value meaned the more obvious symptom and the endpoints could be discerned easily during the process.更多还原