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Ria T. Leonard, Terril A. Nell, Lars Hoyer, Jim E. Barrett, and David G. Clark

Postproduction evaluation trials have been developed in North America and Europe to test postproduction performance of potted roses from individual growers. The results of the trials have been compiled on the “Roses On The Web” Website (www.parade.dk). Roses on the WEB is a cooperative project between Poulsen Roses ApS, Denmark, the Danish Institute of Agricultural Sciences, and the Univ. of Florida. The goal of the Website is to provide growers participating in the evaluation trials a quick and easy way to obtain results on the postproduction quality of their roses. Plants receive 4 days of simulated transport, sleeved in a box in darkness at 16 °C. After transport, plants are maintained at 20 °C at 8 μmol·m–2·s–1 for 12 hours/daily. Relative humidity is maintained at 55% ± 5%. To determine quality, several parameters are recorded at day 0 (day of arrival), 11, 18, 22, and 28. The recordings include the number of open and damaged flowers and buds, percentage of damaged leaves, and the presence of disease and pests. Based on the results of all the measurements, each plant is given a postproduction rating or index, indicating quality. Results from each trial are tabulated and stored on the Website. Growers are able to view their results by entering a password. Growers can evaluate their quality over time and are also able to compare their quality with other growers. Many quality problems are manifested in the postproduction environment and can often be directly related to incorrect greenhouse conditions and/or cultural practices. “Roses On The Web” is a tool that provides quick, up-to-date information that can be crucial to the success of a grower. Differences in quality were found based on grower, time of year and variety.

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David G. Clark, Christopher Dervinis, James E. Barrett, and Terril A. Nell

Experiments were conducted to determine if the seedling hypocotyl elongation and petal abscission assays could be used to identify differences in ethylene sensitivity among seedling geranium (Pelargonium ×hortorum) cultivars. When seedlings of six geranium cultivars were germinated and grown in the dark in the presence of the ethylene biosynthetic precursor 1-aminocyclopropane-1-carboxylic acid (ACC) at various concentrations, they exhibited the triple response (measured as reduced hypocotyl length). While seedlings from all six cultivars were sensitive to ACC, `Scarlet Elite' seedlings were most sensitive, and `Multibloom Lavender', `Elite White' and `Ringo 2000 Salmon' seedlings were the least sensitive when germinated and grown on 20 mm [2022 mg·L-1 (ppm)] ACC. Florets representing three developmental stages of each of the six cultivars were exposed to 1 μL·L-1 of exogenous ethylene for 0, 30, or 60 min to determine if differences in cultivar sensitivity could be determined for petal abscission. Of the six cultivars tested, `Ringo 2000 Salmon', `Multibloom Lavender' and `Elite White' were the least ethylene sensitive. Florets were also self-pollinated to test for cultivar differences in ethylene synthesis and subsequent petal abscission. Ethylene production and petal abscission were both promoted in self-pollinated florets compared to nonpollinated florets. `Ringo 2000 Salmon', `Multibloom Lavender' and `Elite White' florets produced similar amounts of ethylene as all other cultivars, but abscised fewer petals after pollination. Our results indicate that the seedling hypocotyls elongation assay may be used to identify geranium cultivars with reduced sensitivity to ethylene. The data also suggest that genetic variability exists among geraniums for both ethylene sensitivity and biosynthesis.

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Oswaldo Macz, Ellen T. Paparozzi, Walter W. Stroup, Terril A. Nell, and Ria Leonard

Research on hydroponically grown mums showed that nitrogen (N) levels applied can be reduced when adequate sulfur (S) is also applied. However, changes in stem length, leaf area, and time-to-fl ower can be affected. Our goal was to evaluate whether reduced N levels in combination with S would affect commercial production and post-harvest longevity of pot mums. `White Diamond' was grown in a peat:perlite:vermiculite medium following a commercial production schedule. N levels applied were 50, 100, 150 and 200 mg/L. S levels were 0, 5, 10, 20, and 80 mg/L. The treatment design was a complete factorial 4 × 5 with 20 treatment combinations. The experimental design was a split-plot with N levels as the whole-plot and S levels as the split-plot factor. Variables measured were plant height, leaf area, days to bud set, days to first color, and days to flower opening. Plants were ship to the Univ. of Florida for postharvest evaluation. Data were analyzed using SAS PROC MIXED AND PROC REG. N and S interactions were significant for all variables measured except flower longevity. Plants receiving 0 mg/L S did not produce inflorescences, had shorter stems, and less leaf area regardless of N levels. Plants receiving 50 mg/L N and some S produced inflorescences, but were of inferior quality to plants receiving 100, 150, and 200 mg/L N. Plants receiving 200 mg/L N and 80 mg/L S showed breakdown of plant architecture. Plants of commercial quality were obtained at 100, 150, and 200 mg/L N in combination with either 5, 10, or 20 mg/L S.

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Andrew J. Macnish, Ria T. Leonard, Ana Maria Borda, and Terril A. Nell

Natural variation in the postharvest quality and longevity of ornamental plants can often be related to differences in their response to ethylene. In the present study, we determined the postharvest performance and ethylene sensitivity of cut flowers from 38 cultivated Hybrid Tea rose genotypes. The vase life of the cultivars varied considerably from 4.5 to 18.8 days at 21 °C. There was also substantial variation in the degree of flower opening among genotypes. Exposure to 1 μL·L−1 ethylene for 24 h at 21 °C reduced the longevity of 27 cultivars by 0.8 to 8.4 days (18% to 47%) by accelerating petal wilting and abscission. Ethylene treatment also significantly reduced rates of flower opening in 17 sensitive cultivars and in six cultivars that showed no ethylene-related reduction in vase life. Five cultivars showed no reduction in vase life or flower opening in response to ethylene exposure. Pre-treating stems with 0.2 mm silver thiosulfate liquid or 0.9 μL·L−1 1-methylcyclopropene (1-MCP) gas for 16 h at 2 °C reduced the deleterious effects of ethylene. The release of 1-MCP from two sachets containing EthylBloc™ into individual shipping boxes also protected flowers against ethylene applied immediately after a 6-d commercial shipment. The duration of protection afforded by the 1-MCP sachet treatment was greatest when flowers were maintained at low temperature.

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Ayumi Suzuki, Ria T. Leonard, Terril A. Nell, Jim E. Barrett, and David G. Clark

It has traditionally been recommended to cut flower stems underwater to reduce blockage and improve water uptake, although little scientific information relates this practice to vase life. The purpose of our study was to evaluate the benefit of this processing technique on quality and longevity of several cut flowers species. Stems were either cut dry or cut wet under deionized water with a stainless steel blade and placed into vases containing a commercial floral preservative. Water samples were obtained from the cutting tank over time during stem processing for bacteria counts. Stems were maintained at 2 °C at 10 μmol·m–2·s–1 (12 h/day). The results were variable from shipment to shipment, possibly due to differences in stem quality or cutting water quality. In most cases, cutting underwater had no effect on longevity of alstroemeria, chrysanthemums, gerbera daisy, roses, or snapdragons. However, in a few instances, cutting underwater improved longevity slightly. Cutting stems underwater was consistently effective in increasing longevity 2-4 days for carnations. Bacteria counts in the cutting tank water after 500 stems were processed were 6/34 × 106 propagules/mL and increased to 1.00 × 107 propagules/mL after 1000 stems. The increase in bacteria decreased leaf quality in roses and reduced the number of snapdragon flowers that opened, but did not affect longevity. In gerberas, however, longevity decreased 2 days. A high concentration of bacteria in the cutting water may effect quality and longevity of many cut flower species and may negate any benefit in cutting stems underwater.

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G.H. Pemberton, Terril A. Nell, Ria T. Leonard, A.A. De Hertogh, Lena Gallitano, and James E. Barrett

Forced `Bumalda' and `Etna' Astilbe were evaluated for postproduction quality and longevity. Plants were sleeved, boxed and held at 9±2C for 3 days to simulate shipping at the following stages of floral development: tight bud (TB), 1-3 florets open, 25% florets open, 50% florets open, and 75% florets open. They were then placed at 21C and 14 μmol·m-2·s-1 (12h daylength) until flower senescence. Percent of inflorescences flowering increased from 34% at TB stage to 94% when shipped with 25 % of the florets open. `Etna' longevity increased from 3 days at TB stage to 12 days at 25% open stage. Optimum quality and longevity occurred when ≥ 25% of the florets were opened at shipping.

In a second experiment, `Bumalda' and `Etna' Astilbe were held at 18, 21 and 24C at irradiance levels of 7 or 14 μmol·m-2·s-1 when 25% of the florets were open. At 18C, longevity increased under 14 μmol·m-2·s-1 from 14 to 17 days. At 24C, longevity was only 10 days for both irradiance levels.