Effects of planting densities on canopy apparent photosynthesis, canopy structure and yield of cotton drip-irrigated under the mulch in Xinjiang Measurement of Evapotranspiration for Drip-IrrigatedWinter WheatUsing Large Weighing Lysimeter in Northern Xinjiang Effect of Water-nitrogen Coupling on Photosynthesis and Soil Water Use of Oil Sunflower in Drip-irrigated Multiple Cropping System