H.C.M. de Stigter, A.G.M. Broekhuysen
The degree of air embolism occurring in a cut rose stem left to dry for a while can be estimated by measuring the quantities of air flowing through stem segments under a slight pressure of 0. 1 bar, and expressing these quantities as percentages of the maximum flow through the individual segments after all water has been removed from the xylem vessels by forcing air through them under a higher pressure.

Apart from this 'primary' embolism which will disappear upon rehydration (if not too severe), we established the occurrence of 'secondary' embolism in cut roses standing in water. This type of embolism develops gradually during vase life as the cut surface of the stem becomes clogged by microbial growth and the water potential of the leaves becomes more and more negative. Initially, in the dark the embolism will disappear more or less completely, but as it becomes more severe, recovery no longer takes place.

Air embolism can be induced experimentally within a much shorter time by causing the stem base to become plugged by a suspension of finely dispersed particulate matter.

Treatments that prevent microbial stem clogging and maintain high water potentials, such as placing the roses in vase water containing slow-release chlorine, or in ice-cold water, also prevent the development of secondary embolism.

It is hypothesized that secondary embolism originates either from cavitation or from air set free from dissolution in absorbed vase water, due to the intensifying tension inside the stem.

It is discussed whether this type of embolism is merely a passive, accompanying effect of intensifying water stress, or actually reinforces the stress initiated by stem plugging.

The air-flow method is a valuable complement to the conventional one using gravitational water flow.

de Stigter, H.C.M. and Broekhuysen, A.G.M. (1989). SECONDARY GAS EMBOLISM AS AN EFFECT OF DISTURBED WATER BALANCE IN CUT ROSES. Acta Hortic. 261, 17-26
DOI: 10.17660/ActaHortic.1989.261.2

Acta Horticulturae