The research of this paper was conducted in drought, high temperature, fungal inoculation and other several different environments to evaluate water use efficiency, photosynthetic characters and other relative items. On the Loess Plateau, (1) 8 varieties were analyzed to see the differences between their water use efficiency, sap flow velocity and gas exchange parameters, (2) using 3 different P levels on another wheat variety Changwu 134 to see the water use efficiency and other characters changes. There w...