Possible roles of soluble carbohydrate constituents in cut rose flowers

To investigate the role of soluble carbohydrates, particularly methyl glucoside, myo- inosital and xylose;, cut 'Sonia' roses were continuously treated with distilled water (control) or a solution containing 30 g.liter(-1) sucrose and 200 mg.liter(-1) 8-hydroxyquinoline sulfate (HQS). Changes in carbohydrate concentrations in different plants of the cut flowers were determined. This treatment extended the vase life of cut flowers and increased fresh weight of petals. Fructose, glucose, and sucrose were the main carbohydrates in petals, whereas the concentrations of others were lower at harvest. Although xylose concentration was very low at harvest, it increased with time; the rest of the carbohydrates changed little with time. Fructose, glucose, and sucrose were the main carbohydrates in the remaining flower part, which were slightly affected by the treatment with sucrose plus NQS. Sucrose, fructose and methyl. glucoside were main carbohydrates in the stem at harvest; their concentrations in the control decreased with time but sucrose plus HQS suppressed this decrease. Sucrose was most abundant in leaves, followed by myo-inositol at harvest. The sucrose concentration in the control decreased sharply during first day after harvest but the treatment with sucrose plus HQS suppressed this decrease. On the contrary, the myoinositol concentration was almost constant with time regardless of the treatment. Treatment with methyl glucoside and xylose markedly promoted flower bud opening, whereas myo- inositol did not. These results suggest that methyl glucoside and xylose are readily metabolized and contribute to flower opening in cut roses.