[Effect of different substrates on photosynthetic characteristics of Iris pseudacorus L. and the capacity of purify wastewater].

The effect of the different substrates on the photosynthetic characteristics, transpiration rate and SPAD value, and capacity of purify wastewater was investigated by pot experiment, based on five ordinary substrates (soil, sand, mixture of soil and sand, mixture of sand and organic matter, and mixture sand, soil and organic matter). Results showed that the photosynthetic characteristics and transpiration rate of Iris pseudacorus L. were influenced by different substrates. The order of the photosynthetic and transpiration rate of Iris pseudacorus L. in soil was high, and that of Iris pseudacorus L. in sand was the lowest. The value of photosynthetic characteristics and transpiration rate of Iris pseudacorus L. in soil were 11.67 micromol x (m2 x s)(-1) and 9.18 mmol x (m2 x s) (-1) respectively, and that of Iris pseudacorus L. in sand were 8.38 micromol x (m2 x s)(-1) and 4.55 mmol x (m2 x s)(-1), respectively. The photosynthetic characteristics and transpiration rate of Iris pseudacorus L. were significantly correlated with the removal rate of permanganate index, NH4(+) -N and NO3(-) -N (p < 0.05). The SPAD value of Iris pseudacorus L. was also influenced by substrates, and SPAD value of Iris pseudacorus L. in soil was high (58.92), followed by mixture soil, sand and organic matter, that of Iris pseudacorus L. in sand was the lowest (51.14). The significant correlation between the SPAD value of Iris pseudacorus L. and the photosynthetic characteristics, transpiration rate, NH(+) -N was also found (p < 0.05). The SPAD vale of Iris pseudacorus L. in different substrates was different, which was used to monitored operation condition of the removal rate of nitrogen in constructed wetland.