Abstract
Using shoot segments of Dendranthema grandiflora (Ramat.) Kitamura ‘Jinba’, hydration with hot water and water containing surfactants was studied in relation to the physical properties of vase water. Under nearly 100% relative humidities, fresh weight recovery was rapid with higher vase water temperatures. The fresh weight measured 6 h after the start of hydration (y) was negatively proportional to the kinematic viscosity of vase water (x) (y = −3.86x + 103.10, R2 = 0.92**), which decreased with an increase in vase water temperature, and water uptake during the initial 6 h (y) was inversely proportional to the kinematic viscosity [y = 10.36x/(−0.28 + x), R2 = 0.94**]. These results indicate that water uptake by cut stems can partly be explained by the Hargen-Poiseuille law and that the promotive effect of hot water on fresh weight recovery is attributed mainly to the decrease in kinematic viscosity by lowering the water conductance in the xylem vessels. The addition of surfactants such as polyoxyethylen (7) lauryl ether and "Shinguramin" to the vase water facilitated hydration even under a low temperature condition. These surfactants decrease surface tension by nearly half, which elevates the matric potential of water sucked into the xylem vessels, resulting in rapid hydration.
