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Abstract

Out of the 25 microorganisms commonly occuring in carnation (Dianthus caryophyllus L. ‘Improved White Sim’) vase solutions, 3 greatly reduced carnation vase life when added individually to vase solutions. Some of these microorganisms also reduced the vase life of roses (Rose hybrida ‘Cara Mia’), chrysanthemums (Chrysanthemum × morifloium Ramat. ‘May Shoesmith’) and other cultivars of carnation (‘Improved Red Sim’ and ‘Improved Pink Sim’). The microorganisms that reduced flower vase life were tentatively identified as a yeast, a fluorescent pseudomonad and a nonfluorescent pseudomonad. A 10-fold reduction in the initial inoculum level affected neither the final microbial concentrations nor the vase life of the test flowers. The effects of the different microbes were not correlated with their effects on solution pH.

Various postharvest treatments were evaluated for effect on longevity and quality of cut Campanula medium L. `Champion Blue' and `Champion Pink' stems. Stems stored at 2 °C either wet or dry had no difference in vase life or percent flowers opened; however, flowers stored dry had a slightly greater percentage of senesced flowers at termination. Increasing storage duration from 1 to 3 weeks decreased vase life. Stems pretreated for 4 hours with 38 °C floral solution (deionized water amended to pH 3.5 with citric acid and 200 mg·L^-1 8-HQC) or a 1-MCP pulse followed by a 5% sucrose pulse solution produced the longest vase life (10.3 or 10.4 days, respectively). Flowers opening after treatments commenced were paler than those flowers already opened and a 24-hour pretreatment with 5% or 10% sucrose did not prevent this color reduction. Stems had an average vase life of only 3.3 days when placed in floral vase foam but lasted 10.0 days without foam. Optimum sucrose concentration was 1.0% to 2.0% for stems placed in 22 °C floral vase solution without foam and 4% for stems placed in foam. High (110 μmol·m^-2·s^-1) or low (10 μmol·m^-2·s^-1) light levels did not affect postharvest parameters, but the most recently opened flowers were paler under low light conditions than under high light conditions. Chemical names used: 8-hydroxyquinoline citrate (8-HQC); 1-methylcyclopropene (1-MCP).

Physostegia purpurea Blake is a native, herbaceous perennial that has potential as a field-grown cut flower. Physostegia stems were harvested with one third of the florets open and were recut underwater in the laboratory. Fresh cut flowers treated with silver thiosulfate (STS) and held in a 2% preservative solution lasted 14 days, while control stems in deionized water (DI) lasted 6 days. Cut stems placed in darkness at 0C for 1 week had 8 days of vase life after removal from storage and treatment with STS and preservative, while stems held in DI after storage lasted only 4 days. Stems held dry at 22.5C and 43% RH for 8 hours before being placed in preservative had similar vase life as flowers placed in preservative immediately after harvest.

Five members of the Proteaceae and 13 Australian native cut flower cultivars were stored for 35 days under standard conditions at 1C to assess their ability to withstand long-term storage and transport. Protea cynaroides L., Leucadendron `Silvan Red', Leucospermum `Firewheel', Thryptomene calycina (Lindl.) Stapf., Telopea speciosissima R. Br., and Verticordia grandtiflora Endl. retained a vase life of at least 7 days after 21 days of storage. Leucospermum cordifolium Salisb. ex Knight, Protea neriifoli R. Br., Chamelaucium uncinatum `Alba', C. uncinatum `Purple Pride', Verticordia monadelpha Turcz., Verticordia plumosa (Desf.) Druce, and Verticordia nitens (Lindl.) Schau. suffered a decline in vase life ranging from 31% to 100% after 14 to 21 days of storage. Species of Verticordia and Chamelaucium were particularly susceptible to fungal infection. Anigozanthos pulcherrimus Hook. and the Anigozanthos cultivars Ruby Delight, Bush Harmony, Bush Haze, and Gold Fever all showed a significant reduction in vase life after 14 days of storage compared with unstored controls.

The effects of the duration of cold storage, as well as the concentration, timing, and means of application of a solution containing 25 mg·L^-1 each of benzyladenine (BA) and gibberellins (GA₄₊₇) on the postharvest quality of cut Asiatic and Oriental lilies (Lilium sp.) were evaluated. Depending on the cultivar, lower leaves began to turn yellow between 1 and 2 weeks after placing non-cold-stored stems in a 20 °C room illuminated 12 h·d^-1 with 8 μmol·m^-2·s^-1 from cool-white fluorescent lamps. Leaf yellowing continued to progress upward until the end of the vase life. Cold storage (3.3 °C) worsened the leaf disorder, particularly, on the Oriental lily `Stargazer'. The longer the duration of cold storage, the earlier the development of leaf yellowing and the higher the percentage of leaves that were chlorotic. In addition, cold storage induced bud blasting, inhibited flowers from fully opening, and reduced the longevity and fresh weight of open flowers and the vase life of cut stems. Spraying leaves with a solution containing 25 mg·L<sup>-1</sup> each of BA and GA<sub>4+7</sub> significantly reduced cold-storage-induced leaf yellowing, bud blasting, and vase life of three of the four cultivars tested. The development of leaf yellowing declined with increasing concentration of BA+GA<sub>4+7</sub>. The susceptibility of `Stargazer' to cold-storage-induced leaf yellowing and bud blasting can be counteracted by a concentration of growth regulators higher than that which was effective for the other cultivars. Timing of the BA+GA₄₊₇ application was not critical, as there were no differences in leaf yellowing or bud development when the solution was sprayed before or after the cold storage. Addition of BA+GA₄₊₇ (0.5 or 2.5 mg·L^-1 of each) to the preservative solution or a pulsed treatment in solutions containing 25 mg·L^-1 each of BA and GA₄₊₇ for 4 hours prevented leaf yellowing, but increased bud blasting. For practical applications, growth regulators can be sprayed prior to or after cold storage in order to improve the postharvest leaf and flower quality of cut lilies.

Heliconia (Heliconia spp.), red ginger (Alpinia purpurata), and bird-of-paradise (Strelitzia reginae) inflorescences have similar stem structures and postharvest handling regimes. Inflorescences, especially heliconia, should be harvested in the morning while still turgid, and at the most suitable stage of development which varies with the species, its proposed use, and market requirements. Treatments that extend postharvest vase life, either or both enhance water uptake or prevent water loss and provide an exogenous energy source. Use of the most suitable temperature for shipping and storage prolongs vase life. Heliconia should be shipped and stored at >10 °C (50.0 °F), red ginger >12 °C (53.6 °F), and bird-of-paradise at >8 °C (46.4 °F). Sucrose (10% w/v), citric acid [150 mg·L^-1 (ppm)] and 8-hydroxyquinoline citrate (250 mg·L^-1) are major chemicals used in pulsing and holding solution for bird-of-paradise. Holding solutions for red ginger are similar except 2% (w/v) sucrose is recommended. The response of heliconia inflorescences to different pulsing and holding solutions has been shown to be negligible. A 200-mg·L^-1 benzyladenine spray extends the vase life of red ginger and heliconia. Hot water treatment of red ginger at 49 °C (120.2 °F) and 50 °C (122.0 °F) for 12 to 15 min extends postharvest vase life, kills most of the pests that infest red ginger, and reduces the geotropic response. The major postharvest problems are saprophytic mold on bird-of-paradise, negative geotropic response of red ginger, and insect infestation of all three flowers. There is no reported method to control the postharvest nectar and slime production on bird-of-paradise that provides a substrate for saprophytic mold growth. Dipping inflorescences in benomyl or thiobendazole (TBZ) at 200 mg·L^-1 does help control postharvest mold growth in bird-of-paradise and heliconia. Compared to most temperate flowers, there is a need for greater understanding of morphological and physiological factors that limit the vase life of heliconia, red ginger and bird-of-paradise flowers.