Estimating the crop coefficient and the water requirement of the Gascogne wheat by using energy balance method in Mashhad

Water productivity Increase is one of the water management solutions in agriculture and increasing its efficiency. The accurate determination of plants water requirement and the accurate value estimate of evapotranspiration is essential for improving water productivity in irrigation network that it can help to improve water management in agriculture. This research was performed to determine the water requirement and crop coefficients of winter Gascogne wheat in station of estimating evaporation within three lysimeter in Ferdowsi university of Mashhad in Aban 1389. In general، the enough growth period of water was available to the plants and the amount of the water potential in soil was always at field capacity. The necessary data for measuring evapotranspiration was obtained the energy balance method at all stages of plant phenology in one-hour intervals from Aban to mid-khordad using energy balance device (DIK-2500). Based on the results، water requirement of wheat in growth period using energy balance and lysimeter methods was estimated respectively 536. 5 and 544. 5mm. Also، the water requirement of the reference plant was obtained 865. 5 mm. The average of the crop coefficients of wheat was estimated 0. 3، 0. 8، 1. 14 and 0. 4 for the four growth stages.