Micro-organisms from freshly harvested cut flower stems and developing during the vase life of chrysanthemum, gerbera and rose cultivars

Abstract

A wide variety of micro-organisms, bacteria and fungi, was isolated from freshly harvested cut flower stems and vase contents of Chrysanthemum (Dendranthema grandiflora) cultivar ‘Spider’, Gerbera cultivars ‘Appelbloesem’ and ‘Fleur’ and Rosa cultivar ‘Sonia’. Fungal spp. were isolated much more frequently than by other authors. Bacterial genera, present on the stems, were mainly also present in the corresponding vase water. The dominant initial stem microflora, Enterobacter, Bacillus spp. and fungi, lost their dominance in the vase water, which after 3 days of vase life showed a predominance of Pseudomonas spp. The longer the vase life, the greater were the changes in the microflora of the vase water, which later again showed a predominance of Enterobacter spp. and often also of Bacillus spp. After ⩾ 10 days of vase life, fungal growth increased dramatically in Chrysanthemum and Gerbera vase water. The unique ecological conditions in the vase fluid and, to a lesser extent, the antagonistic activities of many of the microbial species of the mixed vase flora will have led to the initial predominance of Pseudomonas spp. and to typical changes in the dominant flora during the course of the flowers' vase life. The microbial load on stems of cut Rosa was found to be much lower than those on Chrysanthemum and Gerbera stems. The end of the vase life of the Rosa flowers was characterized by ‘normal’ senescence symptoms or by weak wilting of leaves and flowers. In Chrysanthemum and Gerbera however an extensive water stress developed. Further studies are required to evaluate the effects of pure cultures of stem micro-organisms on the vase life of cut flowers. For the prevention of microbial activity in cut-flower vase water, which leads to a shorter flower vase life, good commercial practices are desirable.