The effects of physiological traits of wheat on photosynthetic water use efficiency in rainfed conditions

Water in arid and semiarid regions is a limitation factor and recognition of water use efficiency is an essential parameter in yield increment of the crop plants. An experiment with 100 wheat lines and varieties was conducted in square lattice design (10×10) to identify the effects of different physiological traits on water use efficiency of wheat under rainfed conditions. Leaf relative water content, rate of water lost, photosynthesis rate, intercellular CO2 concentration, transpiration rate, stomatal conductance and chlorophyll index were measured at flowering stage. In stepwise regression analysis of PWUE as dependent variable, photosynthesis rate, transpiration rate and intercellular CO2 concentration entered to model and explained 88% of the total variance of PWUE. Path analysis showed that photosynthesis rate had positive and transpiration rate and intercellular CO2 concentration had negative effects on this trait. According to our results, selection of plants with higher photosynthesis rate and transpiration rate and lower intercellular CO2 concentration is recommended to improve PWUE.