Effect of hot water on red ginger (Alpinia purpurata) inflorescence vase life

Different ranges of temperatures and exposure times were studied to determine suitable hot water treatments to extend red ginger vase life. Hot water at 50 degrees C for 12-15 min showed a high potential to prolong vase life. The threshold for damage on the flower bracts was represented by the equation temperature = 55.23 - 4.5 log(exposure time, min), R-2 = 0.97 (P = 0.0001), with less than or equal to 5% of total bracts damage. Damage caused by hot water treatments correlated with the amount of rainfall 7 days before harvest (P = 0.004), whereas vase life of hot water-treated flowers showed a negative correlation with the amount of rainfall 1 month before harvest (P = 0.04). Preconditioning flowers at 40 degrees C for 15 min before hot water (50 degrees C, 12 min) significantly reduced damage from the hot water treatment. Preconditioned flowers lost their tolerance to the hot water treatment if the intervening period between preconditioning and hot water treatment, was longer than 6 h. The suggested treatment to extend vase life was a preconditioning at 40 degrees C for 15 min. standing in the bucket of water at room temperature (22 +/- 2 degrees C) for 1 h, and then a hot water treating at 50 degrees C for 12-15 min. (C) 1998 Elsevier Science B.V. All rights reserved.