Abstract: In this paper, the single and joint toxicity of perchloroethylene (PCE) and cadmium (Cd) on grass carp (Ctenopharyngodon idellus) was observed by static test method, and the joint toxicity was evaluated by additive index method. The results showed that the LC₅₀ of PCE and Cd in 24, 48, 72 and 96 h was 49.12, 41.68, 36.37 and 34.30 mg·L^-1, and 45.58, 34.81, 28.63 and 24.05mg·L^-1, respectively. Both the two test chemicals had high toxicity on C. idellus, and Cd had higher single toxicity than PCE. When the toxicity ratio was 1∶1 and exposure time was 24, 48, 72 and 96 h, the LC₅₀ of PCE and Cd was 24.63, 12.54, 9.88 and 7.08 mg·L^-1, and 17.11, 8.71, 6.87, 4.92 mg·L^-1, and the additive index (AI) was 0.14, 0.81, 0.95 and 1.43, respectively, indicating that the joint toxicity of PCE and Cd was synergistic, and increased with time. At the concentration ratio of 1∶1, the LC₅₀ of PCE and Cd in 24, 48, 72 and 96 h was 17.00, 11.81, 10.61 and 9.19 mg·L^-1, and 17.00, 11.81, 10.61 and 9.19 mg·L^-1, and the AI was 0.39, 0.70, 0.51 and 0.54, respectively, and the joint toxicity was also synergistic.

Key words: ABA, apple, sugar metabolism, transportation., ¹³C-photosynthate