To explore the physiological mechanism of cowpea varieties under water stress, the effects of water stress on the growth,photosynthetic characteristics and water use efficiency of cowpea with different drought resistance were studied. The results showed that water stress significantly inhibited the growth of cowpea,lowered the chlorophyll content, leaf water potential(LWP), leaf net photosynthetic rate(Pn) and transpiration rate(Tr),and increased the water use efficiency. Compared the two varieties,water st...