A silver thiosulfate (STS)-mediated increase in pathogen susceptibility was investigated using shoot cuttings from stock plants of pelargonium (Pelargonium hortorum Bailey cv. Ringo Scarlet) with and without STS treatment. Callusing and rooting were reduced in shoot cuttings from ST&treated plants. The pathogen-tolerant tissue (no STS) was shown to produce enhanced levels of phenolic esters and glycosides during wound healing. Reactivity to the histochemical stain phloroglucinol-HCL was also enhanced during wound healing in cuttings from plants that had not received a silver treatment.
Christa Stark Whalen and George J. Wulster
Jessica D. Lubell and Mark H. Brand
(N) at every irrigation (200 mL/container). Plants were ≈6 inches high with two shoots when foliar sprays of STS were initiated. Silver thiosulfate solutions (0.3 and 3 m m ) were prepared by mixing silver nitrate with STS in a molar ratio of 1:4, per
Jessica DiMatteo, Lauren Kurtz, and Jessica D. Lubell-Brand
produce pollen grains that contain only X gametes that, when crossed with eggs from female plants, result in all-female seed ( Mohan Ram and Sett, 1982 ). Female plants can be masculinized by treatment with silver nitrate or silver thiosulfate (STS
B.K. Behe and T.S. Krentz
Research shows differences among flowering species in ethylene sensitivity in response to ethylene inhibitors, including silver thiosulfate. Buddleia sp. is an arching shrub with spike-shaped inlforescences in a wide range of colors, including pink, purple, yellow, and white. The objective of this study was to determine optimal pulsing time of silver thiosulfate to maximize the postharvest life of five cultivars of Buddleia sp.: `Empire Blue', `Lochinch', `Nanho Blue', `Pink Delight', `Royal Red', and `Sungold'. Flower stems harvested at 1/3 to 2/3 development were transported to a simulated consumer environment. Stems were recut under water and pulsed for 0, 30, 60, and 120 min prior to placing them in a solution of deionized water and Floralife at 10 3 g·liter–1. No silver thiosulfate treatment was more effective than the control at extending vaselife, increasing floret development, or increasing stem fresh weight.
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.
Michael R. Mason and William B. Miller
Interactions of ethephon and irradiance reduction were investigated in terms of flower bud blasting in Easter lily (Lilium longiflorum Thunb. `Nellie White'). Silver thiosulfate (STS) was investigated as an inhibitor of ethylene-induced bud abortion. Fourteen days of 92% irradiance reduction significantly increased bud abortion when plants were exposed to 2.1 mm ethephon. Bud abortion was 39% and 60% for plants grown in ambient and reduced irradiance, respectively. Silver thiosulfate was applied to plants 2 or 3 weeks after the date of the first visible bud, followed by ethephon treatment 2 days later. Bud abortion was significantly reduced by 1 or 2 mm STS, without phytotoxicity. Pretreatment with 1 or 2 mm STS as early as 4 weeks before ethephon exposure significantly reduced ethephon-induced bud abortion. Silver thiosulfate application could inexpensively reduce flower bud abortion during latter stages of greenhouse forcing of Easter lilies.
The postharvest quality of miniature pot roses is limited by bud abscission and premature flower senescence. Rosa hybrida `Victory Parade' plants were treated with ethephon to study their sensitivity to ethylene and with silver thiosulfate (STS) to investigate its inhibitory effects on ethylene action. Bud abscission and flower senescence were promoted by spraying plants with ethephon, and the longevity of individual flowers and whole plants was reduced. All STS concentrations (0.4, 0.8, 1.2, 1.6 mM improved postharvest keeping quality. Bud abscission and flower senescence were decreased and the longevity of flowers and whole plants was improved by applying STS. Chemical name used: 2-chloroethylphosphonic acid (ethephon).
Wen-Quan Sun and Nina L. Bassuk
The effects of silver thiosulfate (STS) on stored and freshly made cuttings of `Royalty' rose (Rosa hybrids) were examined in relation to rooting and subsequent budbreak. STS pretreatment at 0.5 mm during storage stimulated budbreak but decreased the percentage of cuttings that rooted and the number of roots. IBA at 4.9 to 9.8 mm inhibited budbreak but this effect was partially reversed by STS. Spraying the cuttings with 1.0 mm STS once daily during the first 5 days of the rooting period also reduced rooting but prevented IBA-induced leaf senescence. Ethephon and spermine, each applied at 0.5 mm before rooting, had no effect on rooting or budbreak. Chemical names used: (2-chloroethyl)-phosphonic acid (ethephon); indole butyric acid (IBA); N,N'-bis(3-aminopropyl) -l,4-buanediamine (spermine).
Dwight R. Tingley and Timothy A. Prince
A survey of 16 cut evergreen species found six clustered groupings of species based on ethylene production at 2 and 21C. Ethylene production (in nanoliters per kilogram of fresh weight per hour) at 21C ranged from 26 for Juniperus virginiana to 2800 for Sequoia sempervirens. Exposure to 0.1 or 1.0 ppm ethylene for 72 hours at 2C resulted in minor effects on two species, while significantly delaying senescence of Sequoia sempervirens. Silver thiosulfate (STS) pretreatment decreased or increased longevity of six species, but all effects were minor. Longevity of cut evergreens when held in preservative solution ranged from 14 days for Pinus sylvestris to 56 days for Chamaecyparis lawsoniana. Senescence symptoms observed were needle abscission, desiccation, and/or chlorosis.
Susan S. Han
Postharvest quality of cut Heuchera sanguinea Engelm. `Splendens' and `Bressingham' was significantly improved and vase life significantly increased by pulsing the inflorescences with 4 mm silver thiosulfate (STS) for 4 hours followed by placing the stems in vase solutions containing 0.5% sucrose and 200 mg·L-1 8-hydroxyquinoline citrate. Under these conditions, nearly all of the buds (>92%) on inflorescences harvested with ≈2% to 3% open flowers developed to anthesis, in comparison with 26% to 28% of the controls. Sucrose concentrations higher than 1% were detrimental and resulted in stem toppling. Treatment with 4 mm STS for 4 hours delayed bud and flower abscission, but longer treatment times resulted in blackening and shriveling of the flower buds. With the absence of sucrose in the vase solutions, flower buds on STS-treated inflorescences did not continue to develop. Ethylene is probably involved in the natural senescence of the flower buds, since exogenous ethylene induced rapid flower abscission, and senescence was delayed by treatment with STS.