In natural condition,the diurnal courses from 9:00 to 19:00 of net photosynthetic rate (Pn),transpiration,water use efficiency (WUE) and meteorological factors of Potaninia mongolica were determined by the Li Cor 6200 portable photosynthetic analyzer.Meanwhile,taken Nitraria tangutorum as contrast,the comparison was carried out.Results showed that diurnal average Pn of Potaninia mongolica is 8.832 μmol·m -2 ·s -1 that is less than 9.449 μmol·m -2 ·s -1 of Nitraria tangutorum...