The Involvement of Water Stress and Ethylene in Senescence of Cut Carnation Flowers

Abstract

Exposing cut carnation (Dianthus caryophyllus, cv. White Sim) to short term (12 h) water stress resulted in a marked increase in the water saturation deficit (WSD) of the petals. Full recovery occurred upon transfer of the flowers to water in humid conditions (r.h. 85%). However, an increase in aminocyclopropane carboxylic acid (ACC) content occurred immediately upon stress. An associated rise in ethylene production following transfer to humid conditions was observed earlier than in the control. Exogenous ethylene, applied alone or in combination with water stress, increased the WSD of the petals. Continuous treatment of cut flowers with amino-oxyacetic acid (AOA), a known inhibitor of ACC synthesis, suppressed ethylene production, delayed the rise in WSD which accompanied development and senescence and hence delayed wilting. Similar results were obtained with short term (2 h) treatment with AOA prior to stressing the flowers. Short term AOA treatment partially inhibited the rise in WSD during the stress period. On the basis of our findings, in particular that no rise in ethylene production occurred during water stress, it is suggested that the effect of water stress is not directly mediated by ethylene. The possible modulatory effect of water stress and AOA on certain characteristics of the petal cell membrane is discussed.