Effect of Vase Water Temperature and Preservative on Water Relation and Flower Opening Characteristics in Cut Roses

The effect of vase water temperature and preservative on the water relation and bud opening characteristics were determined in cut roses. Freshly harvested 'Red Sandra' roses (Rosa spp.) were held in distilled water (Control), ambient-temperature (22.8℃) preservative solution (AT-Solution), or low-temperature (7℃) preservative solution (LT-Solution), and kept in an environment-controlled room (23℃, 60% RH and 12-h photoperiod at 20 μmolㆍm-¹ㆍsec-¹ PPF). Treatment effects evaluated were vase life, flower diameter, and changes in fresh weight and water uptake. Differences in water flow were determined by monitoring stem water flux rate, leaf temperature, and leaf boundary layer resistance in Control and LT-Solutions. Changes in flower opening were monitored by using CCD camera and image analysis software. While showing lower water uptake rate in the initial stage, roses held in preservative solutions exhibited a higher fresh weight, a larger flower diameter, and longer positive water balance duration, compared to Control flowers. The rate of water uptake was the lowest in AT-Solution and the highest in LT-Solution. Consequently, the vase life of cut roses held in LT-Solution was extended by 7.6 and 2.6 days compared to those in Control and AT-Solution, respectively, indicating a synergistic effect of low-temperature water and the preservative solution. A rapid decrease in stem water flux rate was observed in Control flowers along with increased leaf temperature and boundary layer resistance. Roses in the LT-Solution displayed a stable stem water flux rate with decreased leaf temperature and boundary layer resistance after day 8. Control flowers began unfolding after day 8 and those in the LT-Solution opened to an angle of 160°. The results indicate that placing roses in low-temperature water resulted in increased water flow and reduced hydraulic resistance, and with a preservative solution, significantly extended vase life.