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  • Author or Editor: W.G. van Doorn x
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Placing a daffodil (Narcissus pseudonarcissus L. `Carlton') flower in a vase with a rose (Rosa hybrida L. Sonia) flower reduced water uptake by the rose and resulted in precocious wilting of its leaves and flower and in pedicel bending. These symptoms were also observed when mucilage from daffodil stems was placed in the vase water. The effects of the mucilage and the daffodil stem were overcome by adding 8-hydroxyquinoline (HQC) to the vase solution. HQC inhibits ethylene production and is an antimicrobial compound. Aminoethyoxyvinylglycine (AVG) or silver thiosulfate (STS), inhibitors of ethylene synthesis and action, respectively, did not alleviate the mucilage effects, but sodium hypochlorite, an antimicrobial compound, did. Bacterial counts in the basal 5-cm segment of rose stems increased after placing mucilage or a daffodil stem in the vase water, and counts were reduced by adding HQC or sodium hypochlorite. One daffodil stem also reduced the vase life of tulips (Tulipa gesneriana L. `Frappant' and `Apeldoorn'), which showed precocious leaf yellowing. This was not alleviated by HQC and was also found when mucilage was placed on the leaf surface. Placing mucilage on the leaf produced no effect in roses. Separating the mucilage indicated that the effect in roses is mainly due to the sugar and polysaccharide fraction and the effect in tulips is due to a fraction containing several alkaloids. The results indicate that the decreased vase life of rose flowers, after one daffodil is placed in their vase water, is due to daffodil mucilage, which, in the rose cultivar tested, blocks water uptake, mainly as a result of increased bacterial growth. In the tulip cultivars tested, the negative effect on vase life is primarily due to mucilage toxicity.

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Cut rose (Rosa hybrida L.) flowers placed in water often wilt prematurely, which is partially due to bacterial accumulation in the stems. Bacterial strains in the stems are mainly pseudomonads and enterobacteria. The possible sources of these organisms were investigated in `Sweet Promise' (trade name Sonia) roses. No bacteria were found in the xylem of intact plants. Cutting the stems with sterile secateurs introduced no bacteria at the cut surface or the stem interior, but cutting with nonsterile secateurs used by rose growers did. The secateurs sampled at rose growers contained Enterobacter agglomerans along with several other bacteria not found inside the xylem of cut flowers but did not contain pseudomonads. Although the plant surface may contain bacteria, freshly cut stems placed in water introduced no bacteria. Bacteria rapidly developed on the cut surface and inside the water-conducting elements when rose stems were placed in tap water, even when the stems had been surface-sterilized. However, there were no bacteria in vase water when the water and the stem surface had been sterilized. Since the stem and the secateurs are not a main source of bacteria inside stems and tap water contains pseudomonads and Enterobacter spp., we conclude that tap water is the main source of the bacteria inside cut rose stems.

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