Effects of 5-aminolevulinic acid on leaf gas exchange and water use efficiency in winter wheat Effect of delayed irrigation at jointing stage on canopy temperature and leaf water use efficiency of winter wheat in wide-precision planting pattern Effects of different film mulching on photosynthesis, transpiration rate and leaf water use efficiency of maize Experimental Study and Mathematical Simulation of Water Use Efficiency in Wheat Leaves Affected by Some Environmental Factors Leaf Water Use Efficiency and Its Relationship with Hydraulic Characteristics in Eight Dominant Trees and Shrubs in Loess Hilly Area during Vegetation Succession