Drought stress is one of the main challenges in agricultural production in many parts of the world. especially in arid and semi-arid regions such as Iran. So far. several studies have been conducted on the way water is absorbed by the root growth of various plants. but the available information about the Koshia plant is still limited. For this reason. this study aimed to investigate macroscopic models of water absorption by roots under water deficit stress conditions on the Koshia plant in the climatic conditions of Ahvaz. This study was conducted in three irrigation levels including 60. 80 and 100% of water requirement and in five replications. based on a completely randomized design and in pots. during two years 2022-2023 and 2023-2024. In this experiment. the weight method was used to determine the irrigation time. By plotting relative transpiration against the absolute value of matric potential. fitting the models of Fedes et al. (1978). Vangenocht (1987). Dirksen et al. (1993) and Homaei (1999). the most appropriate model was determined using the statistical indices of maximum relative error (ME). coefficient of determination (R). root mean square of absolute and normalized errors (RMSE and NRSME). modeling efficiency or model efficiency (EF). residual mass coefficient (CRM) and correlation coefficient (r). The results showed that during both years studied. for the treatments of 80 and 60 percent of water requirement. the Vangenochten (1987)a model with statistical indices (R2=0.55 and RMSE=0.122) and (R2=0.53 and RMSE=0.120) (for the first and second years. respectively) showed a better fit to the measured data than other models and was introduced as the best model for reducing absorption. Also. in the treatments of 80 and 60 percent of water requirement separately. the Vangenochten (1987) model was introduced as the superior model.