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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).

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‘Dama Taronja’ and ‘Dama Rosa’ are mid-early ripening apricot cultivars ( Prunus armeniaca L.) from the apricot breeding program at Instituto Valenciano de Investigaciones Agrarias (IVIA). They have optimal productivity, excellent fruit quality

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Poor germination in Rosa spp. has hindered breeding programs for years. Several methods exist to increase germination of rose seed. Unfortunately no consensus exists on the best method, or if any one method is best for all rose types. Rose seeds from a R. wichuraiana × Old Blush hybrid were broken into 3 replications with an average of 400 seeds per replication. Seeds were leached at room temperature with tap water for a period of 0, 3, 7, or 14 days. Constant filtration and aeration were supplied. After leaching, seeds were placed on either moist milled sphagnum moss or agar. Seeds were then placed in a cold stratification (≈2.8 °C) treatment for 8 to 12 weeks. Individual seedlings were planted when a root was visible. The combination of no leaching plus the moist milled sphagnum moss treatment significantly increased germination over leaching for 3 or more days and agar.

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The surface structure of rose (Rosa multiflora L. cv. Montse) leaves formed in vitro under several environmental conditions (light level, relative humidity) and with various growth regulator treatments was studied by light and scanning electron microscopy. The epidermis from leaves developed in cultures grown under a higher light level and a lower relative humidity (80 μmol·s-1·m-2 and 75% RH) than the conditions used in commercial laboratories (25 μmol·s-1·m-2 and 100% RH) showed anatomical modifications of the epicuticular wax, stomata, and epidermal cells similar to that of greenhouse-grown plant leaves. These results indicate that cultured plantlets can resemble greenhouse-grown plants under modified environmental conditions. In vitro pretreatment will reduce transplant losses and shorten the acclimatization period in the greenhouse.

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Abstract

Four Rosa hybrida cultivars were grown in 100 to 500, 700 to 1300, and 1500 to 2500 ppm CO2 atmospheres for at least half the daylight hours from November to May. Production was studied continually for 24 months.

Numbers of flowering stems and lateral buds, fresh weight, and stem length were greater in CO2 supplemented atmospheres on hybrid tea and floribunda roses. Non-flowering percentages were lower for floribundas in CO2 enriched atmospheres. Greater leaf abscission and less root development were noted for hybrid tea and floribunda roses in 1500 to 2500 ppm CO2. Higher yields in non-CO2 supplementation periods (May to October) largely reflected growing conditions rather than CO2 effects.

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The growth of Rosa × hybrida and Exacum affine under different spectral filters was evaluated. Three filters that altered light quality were developed. One, a red textile dye, filtered out much of the blue/green portion of the light spectrum but did not change far-red to red (FR/R) light ratio. Another, a blue textile dye, raised FR/R by filtering out a portion of red light. The third, a salt (copper sulfate) lowered FR/R by filtering out a greater portion of far-red than red light. Two controls were used that did not alter light quality. The filters were installed in specally built growth chambers. Photosynthetic Photon Flux Density (PPFD) was adjusted to equal values in each chamber.

Plants of both species were significantly shorter and had higher leaf chlorophyll, when grown under the low FR/R filter.

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Rosa × hybrida `Meijikatar' plants were fertilized on weekdays with Hoagland's solution at 100, 200, or 300 mg·liter-1 nitrogen. Prior to simulated shipping, plants were treated with benzyladenine at 0, 25, 50, or 100 mg a.i.·liter-1. Plants were subsequently paper sleeved and stored in cardboard boxes in darkness at 16 C for 5 days.

On the day of harvest, plant height and number of flowers per plant were not affected by production nitrogen level. After removal from simulated shipping, total chlorophyll was increased in the lower leaves of plants grown at higher nitrogen rates and treated with higher rates of benzyladenine. Three and five days after removal from simulated shipping, the least percent leaf chlorosis was observed on plants treated with higher rates of cytokinin, but there was no effect of production nitrogen regime.

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Rosa × hybrida `Meijikatar' plants were fertilized on weekdays with Hoagland's solution at 100, 200, or 300 mg·liter-1 nitrogen. Prior to simulated shipping, plants were treated with benzyladenine at 0, 25, 50, or 100 mg a.i.·liter-1. Plants were subsequently paper sleeved and stored in cardboard boxes in darkness at 16 C for 5 days.

On the day of harvest, plant height and number of flowers per plant were not affected by production nitrogen level. After removal from simulated shipping, total chlorophyll was increased in the lower leaves of plants grown at higher nitrogen rates and treated with higher rates of benzyladenine. Three and five days after removal from simulated shipping, the least percent leaf chlorosis was observed on plants treated with higher rates of cytokinin, but there was no effect of production nitrogen regime.

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Tropical hibiscus ( Hibiscus rosa-sinensis L.), also commonly known as the shoe flower or chinese hibiscus, is a widely planted tropical flowering shrub throughout the world. This cultivated species is generally a highly heterozygous polyploid of

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When compared with exposure to darkness, exposing Hibiscus rosa-sinensis L. `Nairobi' plants to red light (635 to 685 nm, 2.9 μmol·m-2·s-1) delayed flower bud abscission, while exposure to far-red light (705 to 755 nm, 1.7 μmol·m-2·s-1) accelerated this process. Flower bud abscission in response to light quality appears to be controlled partly by the presence of leaves. The delay of bud abscission was positively correlated to the number of leaves being exposed to red light. Excluding the flower buds from exposure to red or far-red light, while exposing the remaining parts of the plants to these light conditions, did not influence the effects of the light exposure on bud abscission. Exposing only the buds to red light by the use of red light-emitting diodes (0.8 μmol·m-2·s-1) did not prevent dark-induced flower bud abscission. Exposing the whole plants, darkness or far-red light could only induce flower bud abscission when leaves were present; bud abscission was totally absent when all leaves were removed. To prevent flower bud abscission, leaves had to be removed before, or at the start of, the far-red light treatment. These results suggest that in darkness or far-red light, a flower bud abscission-promoting signal from the leaves may be involved.

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