PHOTOSYNTHESIS, CHLOROPHYLL FLUORESCENCE CHARACTERISTICS, AND CHLOROPHYLL CONTENT OF SOYBEAN SEEDLINGS UNDER COMBINED STRESS OF BISPHENOL A AND CADMIUM

摘要

Bisphenol A (BPA) is ubiquitous in the environment because of its continual application in plastics and the epoxy resin industry. Cadmium (Cd) is a highly toxic heavy metal element mainly used in smelting, electroplating, and plastic and dye manufacturing. Pollution as a result of BPA and Cd exists simultaneously in many agricultural regions. However, little information is available regarding the combined effects of BPA and Cd on plants. The combined effects of BPA and Cd on the photosynthesis, chlorophyll fluorescence, and chlorophyll content of soybean seedlings were investigated using noninvasive technology. Combined treatment with 1.5 mg/L BPA and 0.2 mg/L Cd synergistically improved the net photosynthetic rate (P_n), initial fluorescence (F_0), maximal photochemical efficiency (F_v/F_m), effective quantum yield of photosystem Ⅱ (Φ_(PSII)). photosynthetic electron transport rate (ETR), and chlorophyll content. Combined treatment with 1.5 mg/L BPA and 3.0 mg/L Cd increased the F_0 and decreased the P_n, F_v/F_m, Φ_(PSII), and ETR, whereas BPA and Cd exhibited an antagonistic effect. Furthermore, combined treatment with 17.2/50.0 mg/L BPA and 3.0/10.0 mg/L Cd synergistically decreased the P_n, F_v/F_m, Φ_(PSII), ETR, and chlorophyll content, although it increased the F_0. Finally, the effects of BPA and Cd on photosynthesis, chlorophyll fluorescence, and chlorophyll content ceased when BPA stress was stopped.