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Two-year lysimeter experiments were conducted to determine groundwater contributions by safflower (Carthamus tinctorius L.) crop. The plants were grown in twenty columns each with a diameter of 0.40 m packed with Silty Clay soil. The experiments were carried out in a complete randomized blocks design with four replicates. In each experiment, five treatments were applied by maintaining groundwater salinity to a control treatment with EC 1 dS/m, while the groundwater salinity of the other treatments was 2, 5, 8 and 10 dS/m, and 0.8 m water table level, respectively. The use of groundwater as a part of crop evapotranspiration was characterized by using daily measurements of the water level in Mariotte tubes. The extra magnitude of irrigation water requirement for each treatment was applied by water with EC of 1 dS/m. The results of experiments showed that for different control treatments with 1 dS/m, 2, 5, 8 and 10 dS/m, the groundwater contributions were achieved as 59, 51, 38, 32 and 19% of the total plant water requirements, respectively.