The effect of transient water stress on sugar metabolism and development of cut flowers.

摘要

Rose (Rosa hybrida cv. Mercedes) cut flowers were held out of water for 11 h at 25鳦 and 50-70% RH, and then replaced in water. The changes in the content of carbohydrates as affected by water stressed was determined. Reductions of 3 and 5.5 units of glucose in corolla and leaves, respectively, of control flowers were measured while in stressed flowers the reductions were 4.2 and 6.2 units, respectively. Stressed cut flowers remained small and failed to open compared to the control which had enlarged flowers and an expanded corolla. The effect of water stress on wax flowers ( Chamelaucium unicatum [C. uncinatum]) was also evaluated. After harvesting the flowering branches, closed flower buds were tagged. The flowering branches were held out of water in a closed carton container for 24 h and then placed in water. During the following days, the numbers of widely open flowers were counted. The number of open flowers was similar in the control and stressed plants for the first 2 days. After 10 days,the number of open flowers in the control had increased to 25. In the stressed branches, 65 open flowers were counted by the end of 10 days. To evaluate the effect of water stress on the concentration of sugars in flower buds, flower buds at 2 developmental stages were tagged and then half of the branches were exposed to water stress conditions. The other branches were placed in water. After 24 h, the tagged buds were sampled and the concentration of soluble sugars was measured. Stress increased the soluble sugar concentration and decreased the starch and fructan concentrations.