Among the different ecotypes of Phragmites communis in the Yellow River Delta,the photosynthetic rate and the stomatal conductance were significantly different.They decreased with the increase of salinity level in the habitat,so the stomatal limitation is one of the main causes decreasing the photosynthetic rate of P.communis. With the increase of salinity level in the habitats,the RuBPCase activity decreased,and PEPCase activity increased.It indicated that,under salt stress,the decrease of the photo...