Irrigation management based on water consumption, for greenhouse roses growing on terrace soils in the Canary Islands

摘要

Experiments were conducted in 2 drainage lysimeters constructed inside a naturally ventilated greenhouse. The original clay soil was mixed with peat and used to fill the lysimeters. Tensiometers were set up at depths of 0.1, 0.3 and 0.5 m to monitorsoil suction values and each lysimeter planted up with rose bushes (1 with cv. Ilseta and the other with cv. Jaguar). Drip irrigation was applied whenever the average suction at 0.1 m reached 10 cbar, and the drainage water measured. A water balance model was developed to predict evapotranspiration and drainage outflow. Crop coefficients were obtained by calculating Penman-Monteith potential evapotranspiration (ET) values inside the greenhouse. Water uptake values were correlated with outdoor radiationmeasurements in order to automate the irrigation system. Results showed a good correlation between mean monthly ET and outdoor radiation values (r = 0.63-0.88) but poor correlation between daily ET values and outdoor radiation (r = 0.22-0.35), which indicates that radiation alone might not be a good irrigation criteria for greenhouses in this area, particularly those with little environmental control.