Tomato is one of the most extensively cultivated horticultural crops in the world. Water supply is important for yield quantity and quality. The aim of the present study is to evaluate the canopy temperature and the yield on processing tomato substances with different water supply. There were two treatments, one of them was the irrigated plant material which got 333 mm water, including the precipitation and the other was the cut off substance which means the watering was stopped at the beginning of the ripening process, there was a control as well which got 189 mm precipitation. The canopy temperature was measured row by row with a Raytek MX 4 type infrared thermometer. The stomatal conductance was measured by AP4 type porometer. There were significant differences between the control and irrigated plants according to the water supply which was formulated the canopy values. The plants with a deficient water supply were decreased the transpiration rate, therefore its cooling effect didn't show up. The permanently irrigated tomato plants' yield exceeded the unirrigated ones with almost 50%. It is emerged from the study that the irrigation has a positive effect on the amount of the harvestable yield. It's came from the regression analysis that over a specific amount of water (285 mm), the ripened yield is affected negatively.
