2.2. Treatments with soluble carbohydrates
The flower spikes were recutto 30 cm and individually placed in a 300-mL glass vessel containing 250 mL of carbohydrate solution. In the other experiments, three flower spikes were placed in a 500- mL glass vessel containing 500 mL of carbohydrate solution. Mannitol concentration was set at 1, 10, 100, 250, or 500 mM, whereas glucose, sucrose, or sorbitol concentration was set at 250 mM because in a preliminary experiment, the most pronounced effect in mannitol treatment was observed at this concentration. All solutions including the control were supplemented with 200 mg L1 8-hydroxyquinoline sulfate (8-HQS) to inhibit microbial proliferation. The spikes were kept at 23 C, 70% relative humidity, and 12-h light at 10mmol m2 s1 from coolwhite fluorescence lamps.