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 ⩽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 ⩾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. [ABSTRACT FROM AUTHOR]