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Julie P. Newman, Michael S. Reid and Linda Dodge

Commercial formulations of silver thiosulfate (STS) were evaluated for their efficacy in promoting postharvest longevity of gypsophila. Argylene, Chrysal AVB, Chrysal OVB, Oasis Dry Flower Conditioner, Rogard RS, and Silflor were compared to the anionic STS complex and to Physan plus sucrose. Flowers were pulse treated, then placed overnight at 2° C in Physan plus sucrose. Flowers treated with Rogard RS, Chrysal OVB, and Physan were held continuously in the solution. Overnight treatments of STS were compared to short pulses at higher concentrations. To simulate the effect of shipment, treated flowers were packed in boxes, then held either for 48 hours at room temperature (12-18° C) or for 60 hours in a range of ethylene concentrations. Individual stems were then placed in Physan plus sucrose. The number of open flowers, buds, and dead flowers was determined on each stem at various intervals. All products effectively extended the display life of gypsophila except Rogard RS and Chrysal OVB. Although overnight treatments with STS formulations were not as effective as pulse treatments, their convenience could warrant commercial use.

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Steven A. Tjosvold, Meng-Jen Wu and Michael S. Reid

Potted miniature roses (Rosa × hybrids L. `Belle Sunblaze') held after production in simulated home conditions (21C, continuous fluorescent light) yellowed prematurely, flower buds and leaves abscised, and flower buds failed to open. These symptoms were accelerated when the plants were exposed to low concentrations (1 μl·liter-1) of ethylene in the absence of inhibitors. Spray application of 100 μl BA/liter reduced leaf yellowing but had no significant effect on flower opening or bud abscission. Spray application of 1 mm silver thiosulfate (STS) strongly promoted flower display but did not prevent leaf yellowing. A combined BA and STS treatment greatly improved the postproduction quality of rose plants, particularly if applied 1 day before harvest. Chemical name used: benzyladenine (BA).

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Julie P. Newman, Linda L. Dodge and Michael S. Reid

Commercial floral products with claimed anti-ethylene effects were evaluated for their efficacy in promoting postharvest longevity of gypsophila (`Perfecta', `Gilboa', and `Golan' baby's breath, Gypsophila paniculata L.). These products were applied according to label directions and compared to a laboratory preparation of silver thiosulfate (STS) prepared as a short pulse treatment and as an overnight treatment; they were also compared to the new anti-ethylene gas, 1-methylcyclopropene (1-MCP). After these pretreatments, the flowers were exposed to ambient air or to 0.7 ppm ethylene gas for 36 hours; other flowers received a simulated shipping treatment. Products containing adequate concentrations of silver consistently extended the display life of gypsophila. Products with low concentrations of silver (<10 ppm) or containing aminoethoxyvinylglycine (AVG) offered no more protection than treatments without anti-ethylene compounds. Overnight treatments with STS were as effective as short pulse treatments. Although 1-MCP pretreatment helped prevent the effects of ethylene on flowers that were open at the time of pretreatment, it provided no protection for buds that opened subsequently. There were no marked differences in ethylene sensitivity among three gypsophila cultivars.

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Margrethe Serek, Edward C. Sisler and Michael S. Reid

A 6-hour fumigation of flowering Begonia ×elatior hybrida Fotsch. `Najada' and `Rosa', B. ×tuberhybrida Voss. `Non-Stop', Kalanchoe blossfeldiana Poelln. `Tropicana', and Rosa hybrida L. `Victory Parade' plants with 1-MCP, (formerly designated as SIS-X), a gaseous nonreversible ethylene binding inhibitor, strongly inhibited exogenous ethylene effects such as bud and flower drop, leaf abscission, and accelerated flower senescence. The inhibitory effects of 1-MCP increased linearly with concentration, and at 20 nl·liter-1 this compound gave equal protection to that afforded by spraying the plants with a 0.5 STS mm solution. Chemical names used: 1-methylcyclopropene (1-MCP), silver thiosulfate (STS).

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Margrethe Serek, Michael S. Reid and Edward C. Sisler

Pretreating `Victory Parade' potted miniature roses (Rosa hybrida L.) with photolyzed diazocyclopentadiene (DACP) inhibited the effects of exogenous ethylene (acceleration of leaf and bud drop). In an ethylene-free simulated interior environment, display life of the treated plants was also greater than that of the controls and similar to that of plants pretreated with the anionic silver thiosulfate complex (STS). DACP caused an increase in the binding constant for ethylene in petals and leaves of `Victory Parade' and `Cara Mia' (a cut-flower rose cultivar). Competitive kinetics for the effects of increasing ethylene concentrations on control and DACP-treated plants are consistent with the hypothesis that the effects of DACP are due to irreversible binding to the ethylene-binding site.

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Margrethe Serek, Rodney B. Jones and Michael S. Reid

The opening and senescence of gladiolus (Gladiolus sp.) florets was accompanied by climacteric or nonclimacteric patterns of respiration and ethylene production, depending on variety, and whether data were expressed on a fresh-weight or floret basis. A climacteric pattern of ethylene production by the youngest buds on the spike (which never opened) was stimulated by cool storage, and was not affected by holding the spikes in a preservative solution containing sucrose. Ethylene treatment had no effect on senescence of the florets of any of the cultivars tested. Pulse treatment of the spikes with silver thiosulfate (STS) improved floret opening but not the life of individual florets. Sucrose and STS had similar but not synergistic effects on floret opening, suggesting that STS improves flower opening in gladiolus by overcoming the effects of carbohydrate depletion.

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Victoriano Valpuesta, Nathan E. Lange and Michael S. Reid

Rapid senescence of day lily flowers (Hemerocallis sp. cv. Cradle Song) has been shown to be associated with a rapid disappearance of proteins. Senescence was significantly delayed by pulsing developing flowers with cycloheximide, an inhibitor of protein synthesis. A cDNA library prepared from mRNA extracted from flowers in the very early stages of senescence was probed with mRNA from flowers at different stages of opening and senescence. Characterization of senescence-specific clones, and implications for the control of senescence in this non-climacteric flower will be discussed.

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Rodney B. Jones, Margrethe Serek and Michael S. Reid

The vase life of cut sunflowers given a simulated transport period (3 days dry storage at 8C) was significantly enhanced by a l-hour pulse with 0.01% Triton X-100 administered before storage. The Triton pulse increased solution uptake during the l-hour pulse, decreased fresh weight loss during dry storage, and significantly improved water uptake thereafter, resulting in greater leaf turgidity and longer vase life. Leaf stomata] conductance measurements indicated that Triton X-100 maintained stomatal opening at a higher level during the pulse and after storage, but had no effect during dry storage. Chemical name used: octylphenoxypolyethoxyethanol (Triton X-100).

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Daryl C. Joyce, Michael S. Reid and Richard Y. Evans

Low concentrations of ethylene induced abscission of leaves and berries from cut branchlets of English holly (Ilex aquifolium L.) and American mistletoe [Phoradendron tomentosum (DC.) Engelm. ex Gray ssp. macrophyllum (Engelm.) Wiens]. Application of 1 μmol of Ag+ per branchlet (as the anionic silver thiosulfate complex, STS) via the transpiration stream was found to retard this abscission. A higher application rate (4 μmol Ag+ per branchlet) stimulated leaf abscission in mistletoe. There were marked differences in sensitivity to ethylene among various types of holly.

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Susan S. Han, Abraham H. Halevy, Roy M. Sachs and Michael S. Reid

Flowering of brodiaea (Triteleia laxa syn. Brodiaea laxa `Queen Fabiola') did not have an obligate requirement for manipulation of temperature or photoperiod. Vernalization of corms reduced the greenhouse forcing phase but did not alter the number of flowers per inflorescence or scape length. Long photoperiods hastened flowering but decreased flower quality and flowering percentage. Scape length, which was not affected by photoperiod or mother corm size, was increased when plants were grown at night temperatures < 10C. Diameter of the apical meristem in the dormant corm, flowering percentage, and flower quality were not affected by a 10-fold increase in corm size above a critical weight (0.6 g). In contrast, the weight and number of daughter corms were closely correlated with mother corm size. The optimum planting depth for brodiaea corms was 10 cm below the soil surface.