Journal of Crop Production and Processing

The emitter discharge is affected by parameters such as pressure, irrigation water temperature, manufacturer’s coefficient of variation, and emitter clogging. In order to study the effects of irrigation water temperature on emitter discharge and to determine the discharge-pressure variations and manufacturer’s coefficient of variations, an experimental trickle irrigation system was designed and studied in the greenhouse, College of Agriculture, Isfahan University of Technology. Since the sensitivity of different emitters to water temperature variations is variable, four different, widely used, types of Iranian emitters including in-line long-path emitter, gun emitter, pressure compensating emitter, and double-chamber tube were used. Each emitter was evaluated under 14 different irrigation water temperature treatments ranging from 11 to 43.5°C.

 The results showed that in general as water temperature increases, the emitter discharge increases linearly in all types, except for the pressure compensating emitter in which the discharge decreases linearly. The emitter uniformity, absolute emission uniformity and Christiansen uniformity coefficient parameters were affected by emitter discharge variations. For each type of emitter under study, the changes in manufacturer’s coefficient of variations due to irrigation water temperature were different. The manufacturer’s coefficients of variations at a water temperature of about 20°C for double-chamber tube, in-line long-path emitter, gun emitter and pressure compensating emitter were equal to 5, 7, 13 and 22 percent, respectively. Moving from gun emitter to the double-chamber tube and finally to the in-line long-path emitter, the sensitivity to irrigation water temperature decreased. Sensitivity to pressure variations decreased in the order of gun emitter, double-chamber tube, in-line long-path emitter, and finally pressure compensating emitter.