| description abstract | To develop a proper irrigation management program, determination of crop water requirements and crop coefficients during growth stages is essential. In addition, water requirements and crop coefficients of most medicinal crops, especially in arid and semiarid climates, have not yet been reported. Experiments were carried out from March 2010 through July 2011 to determine the water requirements and single and dual crop coefficients of coriander in a semiarid climate. Three drainable lysimeters, each with diameters of 1.20 m and soil depth of 1.40 m, were used. The Penman-Monteith and water balance equations were applied to determine plant potential and actual evapotranspiration (ET). In all lysimeters, the irrigation was carried out after 30% depletion of available soil moisture to avoid any water stress during the planting period. The moisture contents of all lysimeters were measured at different depths of 20, 40, 60, 80, 100, and 120 cm by time-domain reflectometer (TDR). The actual ET and single and base crop coefficients for the initial, developing, middle, and final stages of coriander growth were determined to be 647 mm and (0.66, 1.19, 1.36, 0.98) and (0.21, 0.72, 1.10, 0.79), respectively. | |
