Determining Crop Water Requirement of Rose Varieties in Hydroponic Greenhouse

One of the strategies to reduce water losses in agriculture is proper irrigation scheduling, which is based on accurate estimation of crop water requirement. In order to determine the evapotranspiration rate of three rose varieties, a one-year study was conducted in a hydroponic greenhouse equipped with drip irrigation system in Arak Plain using drainage type lysimeters. Reference evapotranspiration was also determined using a drained micro-lysimeter with grass. The results showed that the total amount of reference evapotranspiration in the greenhouse was 1608 mm. Also, the total evapotranspiration value of Utopia rose during this growth period was 1423 mm, Dolcevita rose 1480 mm and White rose 1313 mm. The annual average of daily evapotranspiration of rose varieties was 3.8 mm/day. Due to rose bushes being perennial, the crop coefficients did not have four growth stages and, therefore, the average coefficients varied between 0.7 and 0.96 in 10-day intervals. The results also indicated that the average crop coefficient of rose varieties was 0.81 over a year and the average amount of applied irrigation water was 20573 m3.ha-1.year-1 for approximately 75000 rose plant /ha.