Water Requirement and Crop Coefficient of Polianthes tuberose L. in Varamin

The main purpose of irrigation is to achieve an optimum amount of yield with an economical use of water according to the crop water requirement. An improved irrigation scheduling would lead to the reduction of the excess water use, and the enhancement of crop production. In order to develop a proper irrigation scheduling, actual crop water requirement must be determined. Accordingly, it was attempted to determine the water requirement of tuberose (Polianthes tuberose L.) irrigated by a drip irrigation system and grown in a glass greenhouse located in Varamin during 1392. In order to calculate the water requirement of the tuberose, a simple water balance method was applied.. Tensiometers were installed at two soil depths and were used to determine the time of irrigation events. Irrigation was applied at any time when the soil suction reached to 30 centibar. The Water requirement of Polianthes tuberose for a 144 day growing season (Jun. to Oct.) was found to be 350 mm. The average actual evapotranspiration of Polianthes tuberose was 2.5 mm/day. Based on the data collected from a Class A evaporation Pan located inside the greenhouse, the monthly crop coefficients for tuberose were between 0.5- 0.7.