EFFECT OF COMBINED POLLUTION OF LEAD AND BENZO[a]PYRENE ON THE PHOTOSYNTHETIC PARAMETERS AND CHLOROPHYLL FLUORESCENCE CHARACTERISTICS OF RYEGRASS

摘要

Studying the responses of photosynthesis and chlorophyll fluorescence parameters of ryegrass to Pb and B[a]P combined stress is very necessary to elaborate the responses of ryegrass to Pb and B[a]P combined stress. Effects of combined pollution of heavy metals lead (Pb) and benzo[a]pyrene (B[a]P) on photosynthetic physiological characteristics of ryegrass were studied through a potted soil culture test. Results demonstrated that low-concentration (0- 100mg?kg~(-1)) Pb and (0-30 mg?kg~(-1)) B[a]P can facilitate photosynthetic pigments of ryegrass to some extent. High-concentration (200-400 mg?kg~(-1)) Pb and (50-100 mg?kg~(-1)) B[a]P combined pollution can influence photosynthesis. Ci of ryegrass leaves increased with the reduction of Pn, Gs and Tr under Pb, B[a]P and their combined stress, indicating that Pn reduction of ryegrass leaves was caused by nonstomatal inhibition. The fluorescence parameters, Fv/Fm, ΦPSII and qP of ryegrass dropped significantly, but qN increases accordingly, indicating that the PSII primary photochemical efficiency of ryegrass leaves and the energy transfer efficiency from antenna pigments to PSII reaction center are influenced by the combined stress significantly.