Journal of Rangeland

Precise estimates of plants water requirement is essential in the water, soil and plant management. Crop coefficient determination is required to prepare appropriate irrigation timing and enhance water resource management. FAO determined crop coefficient (Kc) of main horticultural and agricultural plants. This study aimed to determine crop coefficient of Medicago polymorpha, using weighing micro lysimeters in Fasa University, located at 140 km south west of Fars province. Circular micro lysimeters with 30 centimeters diameter and 40 centimeters depth were used in three replications to measure Kc of the species. According to the results, various growth stages of the species in a normal growing season including initial, developing, mid-season and late season stages take 5, 25, 35 and 15 days respectively. The crop coefficient (Kc) of these growth stages were 0.59, 0.95, 1.32 and 0.74, respectively. Results showed that Medicago polymorpha requires 541 mm of water during a growth season, therefore it has low water requirement and can be used in rangelands rehabilitation programs in arid and semi-arid regions.