Abstract of a paper presented to the 32nd Annual General Meeting of the
Australian Society of Plant Physiologists, Melbourne.October 1992
The influence of vase solution bacteria on the longevity of cut Boronia heterophylla flowers
Virginia G. Williamson and John A. Milbum Department of Botany, University of New England, Armidale, N.S.W. 2351
Boronia heterophylla F. Muell. (red boronia) has a reported vase life of two days in water, but t shows a positive response to vase solution additives. Longevity was tested using nine vase solution treatments (pH 2.5 to 5.7). Vase life ranged from 4.2 days (10 mM citric acid + 50 ppm chlorine, pH 2.5) to 12.9 days (STS pulse, then distilled water, pH 5.7). Solutions containing 50 ppm chlorine resulted in decreased longevity, whereas the STS pulse, an ethylene inhibitor, significantly increased vase life. The end of vase life was deemed to have occurred when >50% of flowers on the raceme exhibited wilting.
The number of colony forming units (cfu) of bacteria in the vase solutions was determined after 11 days. The solution which had the greatest number of bacteria (4.0 x 10^10 cfu/mL), was also the solution in which flowers lasted the longest: the STS pulse, then distilled water. The second highest number of bacteria (1.0 x 10^10 cfu/mL) was found in the germicide solution, 250 ppm 8-hydroxyquinoline citrate (pH 3.1), in which the flowers lasted 6.5 days. There did not appear to be a correlation between longevity and pH, or longevity and bacterial number. It is concluded that the vase life of B. heterophylla is influenced by the vase solution composition, rather than pH or the number of bacteria present.