ISHS Acta Horticulturae 181: III International Symposium on Postharvest Physiology of Ornamentals
STORAGE ENVIRONMENT RELATED STRESSES AND FLOWER SENESCENCE |
| Authors: | S. Mayak, J.D. Faragher |
| Abstract:
The effects of water stress and temperature, components of low temperature storage, were evaluated. Severe transient water stress, such as to induce a loss of 20% or more in fresh weight, results in advanced onset of the rise in rate of ethylene production. At the same time there is an increase in microviscosity of the cell me branes. These changes, however, do not occur during the stress phase, but considerably later. i.e., about 24 to 36 h after termination of stress. The effect of water stress in shortening rose petal longevity can be alleviated if immediately following stress the petals are detached and placed in water. This suggests that the water stress effect is primarily associated with the induction of an obstruction to water uptake by the petals. Water stress in carnations can be relieved if the flowers are pulse-treated with aminooxy acetic acid, an inhibitor of 1-aminocyclopropane-1-carboxylic acid and ethylene biosynthesis. Since the inhibitor exerted its effect while ethylene synthesis was low, this suggests that the low level of ethylene is important in mediating the stress effect. At low temperature ethylene biosynthesis follows a typical climacteric course. However, the rise in the rate of ethylene production is delayed, although maximum rates of production are similar to those observed at ambient temperature. Also, the high rates are maintained for a long time without visible development of symptoms of senescence. During storage, well before the rate of ethylene production starts to rise, X-ray analysis reveals an increase in the phase transition temperature (Tc) of the cell membranes. This physical change is a consequence of an alteration in the lipid molecular species. When neutral lipids extracted from stored flowers are subjected to interaction with phospholipids, the Tc of liposomes prepared from them is increased, thus clearly indicating that alterations in the neutral lipids are among the first changes to occur in response to the storage environment. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
