Vase Water Bacteria Isolations and Their Effects on Vase Life of Cut Zinnia elegans

Research has shown that bacterial growth in vase solutions can lead to stem vasculature blockage causing petal and leaf wilt, bent neck, or similar water stress related symptoms that reduce vase life. However, some species of cut flowers are not negatively affected by high bacteria counts in vase solution. Therefore, controlling the species of bacteria present in the vase solution may be more important than maintaining low microbial population levels. This research isolated and identified ten bacteria species associated with cut Zinnia elegans postharvest and investigated the effects of pure cultures on vase life of cut Zinnia ‘Benary’s Giant Wine’, including: Pseudomonas fulva, Serratia ficaria, Rhizobium radiobacter, Chryseobacterium sp., Pantoea ananatis, Bacillus pumilus, Chryseobacterium daejeonense, Brevundimonas sp., Escherichia coli K 12, and Pseudomonas marginalis.  Cut Zinnia stems inoculated with P. fulva and E. coli K 12 had significantly greater vase life of 9.5 and 9.4 d, respectively compared to  the nutrient broth control, P. marginalis, P. ananatis, and R. radiobacter (7.3, 7.0, 6.9, and 6.8 d, respectively). The deionized (DI) water control had a vase life of 8.6 d. The other bacterial species had an intermediate vase life, which were statistically similar to each other and to the DI water control. There was no significant difference in water uptake, percent incidence of termination criteria, change in vase solution pH and electrical conductivity, and bacteria concentrations in the vase at termination among all treatments.  This research shows that bacteria species present in the vase solution have an effect on vase life in addition to number of bacteria. Knowing the effects of different bacteria may lead to novel postharvest treatments.