Study was carried out on net photosynthetic rate and chlorophyll fluorescence parameters of flag leaves of wheat cultivar Zhengzhou 9023 under limited irrigation and nitrogen application regimes. The results indicated that significant difference existed among irrigation treatments on grain yields and the photosynthetic parameters such as net photosynthetic rate(Pn),PSⅡ potential activity(Fv/Fo),the maximal quantum efficiency(Fv/Fm)of PSⅡ, photochemical quenching coefficient(qP) and non-photochemical quenchi...