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Daniel C. Bowman, Richard Y. Evans and Linda L. Dodge

A study was conducted to determine the potential for using ground automobile tires as a container medium amendment. Rooted cuttings of chrysanthemum [Dendranthema × grandiflorum (Ramat.) Kitamura] were planted in 1.56-liter pots containing 1 sand:2 sawdust (v/v) or media in which coarsely or finely ground particles of rubber substituted for 33%, 67%, or 100% of the sawdust. Amendment with the coarse material decreased total porosity and container capacity and increased air-filled porosity and bulk density relative to the sawdust control. Amending the medium with the fine material did not appreciably alter total porosity, container capacity, or bulk density, but did increase air-filled porosity. Plant height, fresh weight, dry weight, and number of open flowers were reduced significantly in rubber-amended media compared to sawdust controls. Rubber amendment reduced shoot tissue concentrations of N, P, K, Ca, Mg, and Cu, but increased Zn as much as 74-fold over control values. There was no accumulation of other heavy metals (Cd, Cr, Ni, Pb) or Na in the tissue due to rubber amendment. This study demonstrates that ground tires might be used as a component of container media in the production of greenhouse chrysanthemums. However, growth reductions and the potential for Zn toxicity may limit the usefulness of ground tires as a substitute for conventional organic amendments.

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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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George L. Staby, Richard M. Basel, Michael S. Reid and Linda L. Dodge

Three commercially available “anti-ethylene” treatment solutions were tested for their effectiveness in protecting carnations (Dianthus caryophyllus L. `Improved White Sim', `Atlantis', and `Nora'), Beard-Tongue (Penstemon hartwegii x P. cobaea `Firebird'), and Delphinium sp. from external ethylene levels ranging from 0.01 to 1.2 ppm. Flowers were treated according to label directions and then exposed to ethylene for 20 or 24 h at 20 to 23C after a 0-, 24-, or 48-h delay. Only the product containing silver thiosulfate (STS) provided protection against ethylene injury, whereas products containing inhibitors of ethylene synthesis identified as analogs of either aminooxyacetic acid (AOA) or aminoethoxyvinyl glycine (AVG) offered little or no protection. The safe commercial use of products containing STS is discussed.