Photosynthetic efficiency of ‘Yanli’ strawberry plants irrigatedwith P fertilizer was measured using a portable photosynthesis sys-tem (CIRAS-2, PP Systems, Massachusett, USA) at morning between09:30 and 11:30 to avoid photoinhibition potentially resulting fromhigh light stress at midday. Measurements were made under sat-urating photosynthetic photon flux densities (1000 mol m−2s−1PPFD) from a LED light source and data were recorded automaticallyat an interval of 2 min until the net photosynthetic rate (Pn) wasstable. The determining parameters included: Pn, internal CO2con-centration (Ci), stomatal conductance (Gs) and transpiration rate(Tr). And the photosynthetic water use efficiency (WUE) was cal-culated as the ratio of Pn and Tr, i.e., WUE = Pn/Tr. Responses weredetermined in ten leaves from different plants for each treatment.