Determining the Crop Water Stress Index for Scheduling Sesame Irrigation with Subsurface Drip Systems under Mediterranean Conditions

Investigating how plants respond to water stress is extremely important for effective irrigation management under changing climatic conditions and diminishing water resources. This study aimed to determine the plant water stress index (CWSI) values of sesame grown in semiarid climate conditions in Antalya province. In the study, the leaf crown temperature of the plant was determined by infrared thermometer (IRT) measurements. In addition, the relationships between yield, irrigation time and CWSI were determined using these index values. In this study, four different irrigation rates (I100, I70, I40 and I0) were created with subsurface drip irrigation method established at 40 cm lateral depths. Thus, full irrigation (I100), irrigation at two different stress levels (I70 and I40) and no irrigation (I0) were included. In the research, a total of 266 mm and 248 mm of irrigation water were given in the first and subsequent years, respectively, under I100 (control) irrigation. Plant water consumption values of control subjects were determined as 288 mm in the first year and 273 mm in the second year. In the mentioned irrigation, the yield per hectare was determined as 1840 kg in the first year and 1800 kg in the second year of the research. By combining the data from the first and second years of the study, the lower limit (LL) values for the case without water stress were calculated with the equation Tc-Ta= 4.67-2.43VPD (r2=0.86, P