Zeynab Gholami - PhD student Irrigation & Drainage Engineering, Shahrekord university
Mahdi Ghobadinia - Assistant Professor of Irrigation and Drainage Engineering, Shahrekord university

Surface temperature measured with infrared thermometers is an important tool for irrigation scheduling which has been in practice for some decades. Several indices have been developed to time irrigation events. The most useful is the Crop Water Stress Index (CWSI). This research was conducted to correlate the crop water stress index (CWSI) with evapotranspiration. in order to apply these relationships to irrigation scheduling. Furthermore, the influence of air and soil parameters in the application of canopy and air temperatures differential (Tc - Ta) for irrigation scheduling of red Bean were investigated. The CWSI was 1.61 x (1 - ET/ETm) due to the fact that CWSI was measured and averaged over a portion of the growing season. the Results of evaluation the effect of time irrigation on yield reduction factor indicate that the coefficient changes at different times of irrigation. So that the maximum amount of this coefficient refers to irrigation time 14 pm.

crop water stress index, evapotranspiration, Red Bean