Single and joint toxicity of cypermethrin and copper on Chinesecabbage (Pakchoi) seeds.docVIP

Abstract The single and joint effects of Cu2+ and cypermethrin（） (CPM) on the seed germination and the elongation of root and shoot of Pakchoi were investigated. The results showed that in solution low concentrations of Cu2+ could accelerate the germination rate of Pakchoi, whereas high concentrations of Cu2+ could inhibit it. CPM could strongly inhibit the germination of Pakchoi in solution. However, in the joint toxicity effect（联合毒性作用）, CPM reduced the phytotoxicity of Cu2+ on the germination of Pakchoi seeds under solution conditions. In the single-factor experiments and joint effect tests of CPM and copper on the seedling growth, it was found that there were significant liner relationships between concentrations of pollutants and root elongation (P 0.05). Copper and CPM had synergic effects（协同作用） on root elongation of Pakchoi in solution cultivation test. However, in soil culture test, these synergistic effects were not significant (P 0.05). Meanwhile, the joint toxicity was more dependent on the effect of copper than that of CPM. The toxicity of the pollutants to seed germination, shoot（芽） and root elongation is in the following sequence: root elongation shoot elongation germination rate. Keywords：Ecotoxicology; Cypermethrin; Copper; Pakchoi; Root elongation; Germination rate; Shoot elongation 1. Introduction Copper is an essential element for all organisms at low concentrations(浓度). While with the frequent use of fungicide（杀菌剂） Bordeaux（波尔多液） mixture (mixture of CuSO4 and Ca(OH)2) in orchard（果园）, the content of copper in the orchard soil increased even to pollution level [1], [2] and [3]. Since heavy metals are not degradable（可降解的）, the accumulation（积聚） of copper in the soil may have long effects on the plants growing on the soil. It has been reported that excess amounts of copper may inhibit photosynthesis（光合作用） of plants and cause chlorosis of leaves（叶片变黄） [4]. On the other hand, synthetic（合成的） pyrethroid insecticides（杀虫剂） are extensively（广泛的） used in