Effect of Soil Texture and Different Levels of Irrigation Amount on Water Requirement and Crop Coefficient of Melia azedarach L. in Karaj Area

The growing population, the need to develop urban green space, water resources scarcity and the competition between different sectors of water consumption have necessitated to determine the accurate crop water requirement of different species in green spaces. In this study, a factorial experiment with two factors (soil texture and drought stress) was conducted to determine evapotranspiration (ETc) and crop coefficient (Kc) of Melia azedarach L. using microlysimeters based on a randomized complete block design (RCBD) with 10 replications. This study was performed in the climatic conditions of Karaj during 2019-2020. Soil texture consisted of clay loam and sandy loam and drought stress levels consisted of 0.3, 0.5, and 0.7 of management allowed depletion (MAD). The results showed that the 10-day ETc under 0.3, 0.5, and 0.7 MAD were 15.35, 13.81 and 12.63 mm in clay loam and they were 19.35, 16.9 and 16.58 mm in sandy loam soil, respectively. In both clay loam and sandy loam soils, the ETc decreased as drought stress increased. During the growing season, total net water requirement of Melia azedarach L. under 0.3, 0.5, and 0.7 MAD in clay loam soil were 445.15, 388.58 and 381.41 mm, and in sandy soil were 353.02, 317.59 and 290.54 mm, respectively. Also, the Kc coefficient of Melia azedarach L. during the growing period in clay loam soil under 0.3, 0.5, and 0.7 MAD were determined to be 0.34, 0.3, and 0.28 and in sandy loam soils were 0.27, 0.24, and 0.22, respectively.