关键词: 秋华柳, 水淹, 镉污染, 三峡库区, 消落带

Abstract: [Objective] This study aimed at revealing variation in the phytoremediation ability of the cadmium-contaminated soil and providing theoretical basis on the adaptive management strategies of Salix variegata under flooding in the water-level-fluctuation zone of the Three Gorges Reservoir Region. For this end, the growth adaptability of S. variegata to flooding-and-Cd stress and its Cd accumulation characteristic under flooding were studied.[Method] The biomass and cadmium concentrations in various parts of cuttings of S. variegata were determined. The plants were treated by four concentrations of cadmium (0, 0.5, 2 and 10 mg·kg^-1 individually, achieved by adding CdCl₂·2.5H₂O to soil), interacted with two water conditions (Control group, CK; Flooding group, FL).[Result] 1) The total biomass, aboveground, stem and leaf biomass of S. variegata were not significantly influenced by flooding-and-Cd stress treatments (P > 0.05), while the root biomass under flooding was less than that of control at the same cadmium concentration. 2) The Cd contents in the aboveground parts of S. variegata were higher in the control groups than in the corresponding flooding groups. Under the concentration of 2 mg·kg^-1 Cd, the Cd contents in branch, leaf, bark and xylem were 12.98, 10.08, 7.47 and 17.2 mg·kg^-1, respectively. 3) Flooding significantly influenced the cadmium contents in various parts of S. variegata (P < 0.05). The Cd contents in branch, leaf, bark and xylem were obviously decreased by flooding. With the increasing of Cd concentration (from 0, 0.5, 2 to 10 mg kg^-1), the Cd contents in those tissues were 39.0%, 23.7%, 34.0% and 51.8% of the corresponding control treatment, respectively. However, the Cd contents of root increased significantly under flooding as compared to the controls, accounting for 133.0% to 390.0%. 4) Cd translocation ability from root to branch in flooding was decreased significantly compared to control (P < 0.05). 5) Cd accumulations in the aboveground and whole plant of S. variegata were obviously reduced by flooding. For instance, with treatment of 2 mg·kg^-1 Cd, the Cd accumulations of total plant and aboveground part under flooding accounted for 56.7% and 35.2% of the control, which were 146.40 μg·plant^-1 and 125.35 μg·plant^-1, respectively.[Conclusion] S. variegata had a high growth adaptation under flooding-and-Cd stress. Cd contents of aboveground parts, Cd accumulations of aboveground parts and total plant of S. variegata were reduced under flooding. In order to enhance the efficiency of phytoremediation in Cd contaminated area of the Three Gorges Reservoir Region, and to prevent the secondary pollution caused by decayed litter, it is necessary to harvest the shoots of S. variegata before flooding every year.

Key words: Salix variegata, flooding, Cd pollution, Three Gorges Reservoir Region, water-level-fluctuation zone