The Effects of Postharvest Storage Temperature on Vegetative Cutting Respiration

Poinsettia `Prestige', New Guinea impatiens `Sonic White', and petunia `Improved Charlie' cuttings were harvested from stock plants, weighed, placed in glass jars, and placed at 10, 15, 20, or 25 °C. Carbon dioxide accumulation was measured and used to determine respiration rates at 2, 6, 10, 24, and 48 hours. Vegetative cuttings have very high initial respiration rates that quickly decline over time. At 2 hours, respiration rates at 25 °C were 5.4-, 2.4-, and 4.3-fold higher vs. 10 °C in poinsettia, New Guinea impatiens, and petunia, respectively. By 48 hours, there was little difference in respiration rates. In a second experiment, poinsettia `Prestige' cuttings were pre-cooled at 10 °C for 0, 3, 6, 12, or 24 hours before being transferred to 20 °C. Respiration rates were measured at 0, 2, 6, 10, 24, 48, and 72 hours in the 20 °C environment. Regardless of pre-cooling duration, respiration rates increased when cuttings were transferred from 10 to 20 °C. Respiration rates of cuttings pre-cooled for 3, 6, or 12 hours were not significantly different from cuttings maintained at constant 20 °C. However, after transfer, cuttings pre-cooled for 24 hours had a respiration rate significantly lower than cuttings maintained at constant 20 °C, but by 72 hours, there were no significant differences.