The effects of B[a]P and Cd on the growth, free-radical metabolism, antioxidants, and photosynthetic fluorescence parameters of Poa pratensis were studied by pot experiments. Results showed that low-concentration Cd (≤ 10mg·kg- 1) increased fresh weight, dry weight, malondialdehyde, superoxide anion radical, glutathione, and ascorbic acid. Conversely, high-concentration Cd (≥ 50mg·kg- 1) significantly decreased the fresh weight and dry weight, photosynthetic gas exchange, and fluorescence parameters. Water-use efficiency increased by 1.55 times compared with the control at high concentrations of B[a]P (≥ 25mg·kg- 1) and Cd (≥ 50mg·kg- 1). Principal component analysis showed that Cd played an important role in co-pollution. P. pratensis mitigated B[a]P and Cd co-contamination toxicity by regulating antioxidant activity and water-use efficiency. P. pratensis can tolerate 1, 5, and 25mg·kg- 1 B[a]P, as well as 1 and 10mg·kg- 1 Cd. P. pratensis was also highly capable of degrading B[a]P and extracting Cd in soils co-contaminated with B[a]P and Cd.
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