Some photosynthetic parameters of 6.0 mM phosphoric acid treated plants and control were measured using the CIRAS-2Portable Photosynthesis System. The result showed that Pn and WUE of plants treated with phosphoric acid increased significantlycompared with those of the control plants, while there was no sig-nificant difference in Gs and Ci between the treated plants and control (Table 4). Pn and WUE increased 28.8% and 16.1%, respectively.