[Hormesis effect of cadmium on Lonicera japonica]

A hydroponic experiment was conducted to study the growth characteristics of Lonicera japonica under the stress of different concentrations (0, 0.5, 2.5, 5, 10, and 25 mg L-1 ) cadmium (Cd), aimed to explore the hormesis effect of low concentrations Cd on L. japonica. At < or =5 mg L-1 of Cd, the maximum root length, plant dry biomass, and the contents of chlorophyll a, chlorophyll b, and carotenoid of L. japonica increased significantly, with the increment being 13. 6%, 11.7%, 14. 0% ,10. 8%, and 54. 5%, respectively, as compared with the control. <5 mg L-1 of Cd also had a definite positive effect on the leaf water content. At> or = 10 mg L-1 of Cd, the growth of L. japonica was inhibited significantly. When exposed to 25 mg L-1 of Cd, the shoot Cd concentration of L. japonica reached 622. 93 mg kg-1 , suggesting that L. japonica had a strong capacity of Cd-hyperaccumulation. The dose range of the hormesis effect of Cd on L. japonica was 0.5-5 mg L-1 of Cd.