A CONTROLLED IRRIGATION METHOD USING INTEGRATED SOLAR RADIATION HAS EFFECT ON BOTH THE PRODUCTION AND QUALITY OF SINGLE-NODE CUTTING ROSE 'VERSILLIA'

A controlled irrigation method by integrated solar radiation was examined to understand the effect of solar radiation-dependent irrigation on the production and quality of a single-node cutting (SNC) rose variety, ‘Versillia’, in an aeroponic system. To determine the optimal ranges of integrated solar radiation, the irrigation system was set using either a time clock or using a sensor of accumulative solar radiation outside the greenhouse that whenever it reached to 1.25, 2.09 or 3.35 MJ•m^-2, irrigation was performed. The fresh and dry weight, length of the flowering shoot, and the diameter of stems, as well as the root characteristics, photosynthesis, and water use effect (WUE) were measured. Results showed that the differently controlled irrigation including a time clock irrigation and integrated solar radiation (ISR) significantly influenced the fresh and dry weight of cut flowers and the length of flowering shoot. A higher stem length and fresh weight of cut flowers resulted from irrigation controlled at ISR 1.25 and 2.09 MJ•m^-2 than that at ISR 3.35 MJ•m^-2. This result was associated with a higher photosynthetic rate in the irrigation controlled at ISR 1.25 and 2.09 MJ•m^-2 than that at ISR 3.35 MJ•m^-2. It is coincident with the result of the highest WUE at ISR 1.25 MJ•m^-2 compared to other treatments. These results indicate that a better growth performance is associated with a higher photosynthesis and water use efficiency resulted from the proper timing and amounts of irrigation. Ranges of ISR between 1.25 and 2.09 MJ•m^-2 appear to be optimal for both the production and quality of rose ‘Versillia’ compared to those of fixed time clock irrigation and those in the irrigation controlled at ISR 3.35 MJ•m^-2.