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Terril A. Nell, Ria T. Leonard, A.A. De Hertogh, Lena Gallitano, and James E. Barret

Postproduction evaluations of two cultivars each of Amaryllis (Hippeastrum), calla lily, Freesia, lily, and paperwhite Narcissus were conducted under postproduction temperatures of 18, 21 and 24C and irradiance levels of 7 or 14 μmol·m-2·s-1. Amaryllis longevity ranged from 10 to 24 days, with an increase of 7 to 10 days at 18C. Excessive stem elongation occurred and was greatest at 24C. Calla lily longevity ranged from 33 to 68 days, with up to a 25-day increase at 18C and 14 μmol·m-2·s-1. Freesia lasted 24 to 33 days with an increase of 6 to 9 days at 18C. Leaf yellowing and stalk elongation was a common problem of Freesia, especially at 24C. Lilies lasted 17 to 31 days, with an increase of 9 to 11 days at 18C. Asiatic lilies were superior to Oriental lilies. Paperwhite Narcissus lasted 13 to 27 days, increasing up to 10 days at 18C. Cultivar differences in longevity and quality were observed. Optimum postproduction conditions ranged from 18 to 21C at an irradiance of 14 μmol·m-2·s-1 for best quality and longevity.

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Trinidad Reyes, Terril A. Nell, James E. Barrett, and Charles A. Conover

The effect of irradiance and fertilizer level on the acclimatization of Chamaedorea elegans Mart. was studied. Chamaedorea elegans was grown for 4 months in 1.6-liter pots under 162, 306, or 564 μmol·m–2·s–1 and fertilized weekly with 20N–4.7P–16.6K soluble fertilizer at 220, 440, or 880 mg/pot. At the end of the production period, plants were moved to interior rooms and maintained for 2 months at 20 μmol·m–2·s–1 for 12 h daily at 21 ± 1C and a relative humidity of 50% ± 5%. At the end of the production phase, the light compensation point (LCP) and the concentration of nonstructural carbohydrates were lower, and chlorophyll concentration was higher the lower the irradiance level. Increasing fertilizer concentration decreased the number of fronds, LCP, and nonstructural carbohydrates. After 2 months in the interior environment, LCP and number of fronds of C. elegans did not differ among treatments. Chlorophyll concentration of plants grown under 564 μmol·m–2·s–1 had increased 61%, while starch in the stem had decreased 43% relative to the concentration found at the end of the production period. In C. elegans grown under 306 μmol·m–2·s–1, stem starch depletion was only 13% during the interior evaluation period. These results indicated that C. elegans grown under the highest irradiance level used reserved carbohydrates in the interior environment while adjusting to low light and producing new leaves. Chamaedorea elegans was best acclimatized at the intermediate irradiance and medium fertilizer concentration.

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Trinidad Reyes, Terril A. Nell, Charles A. Conover, and James E. Barrett

Effects of three light intensities (564, 306 and 162 μmol m-2 s-1) and three fertilizer rates (220, 440 and 880 mg/15 cm pot, weekly) were evaluated on acclimatization potential of Chamaedorea elegans. Treatments were applied during four months under greenhouse conditions after which plants were placed indoors (20 μmol m-2 s-1, 21±2C and 50% RH) for two months. Light compensation point (LCP) was significantly reduced by decreasing light intensity and increasing fertilizer rates. Leaf and root fresh and dry weights increased with irradiance while shoots were not affected. Chlorophyll a levels were higher in plants grown under the lowest light intensity. Carbohydrate content is being analyzed and anatomical examination of leaves studied. Plant performance indoors will be discussed. These studies demonstrate that Chamaedorea, a monocot, acclimatizes similarly to dicots.

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Trinidad Reyes, Terril A. Nell, James E. Barrett, and Charles A. Conover

This experiment was conducted to evaluate the interior performance of Chrysalidocarpus lutescens grown for 8 months under 481, 820, and 1241 μmol·m–2·s–1 and fertilized weekly with a 20N–4.7P–16.6K soluble fertilizer at 440, 880, and 1660 mg/pot. Afterwards, plants were placed indoors and maintained at 20 μmol·m–2·s–1 for 12 h daily at 21±1C and a relative humidity of 50%±5% for 3 months. At the end of the production phase, light compensation point (LCP) varied from 243 μmol·m–2·s–1 at the high irradiance level to 140 μmol·m–2·s–1 at the lowest one. Chlorophyll concentration in the leaves was not affected by irradiance or fertilizer rate. Starch concentration in stems and roots were higher the lower the fertilizer rate applied during production and the higher the irradiance level. After 3 months indoors, LCP declined for all the treatments, but the lowest LCP reached, 126 μmol·m–2·s–1, was still too high if the plant has to survive an interior environment. After the interior holding period, a 45% to 55% reduction was observed on leaf, stem, and root soluble sugar concentrations, and stem and root starch concentrations decreased by 97%, and 62% to 72%, respectively, compared to the concentration at the end of production. The number of fronds increased in all treatments during the postproduction evaluation. However, the drastic carbohydrate concentration depletion during the interior holding period indicates that C. lutescens is not a species for extended use under very low interior light conditions.

Open access

David A. Gilbertz, James E. Barrett, and Terril A. Nell

Abstract

Single stem Euphorbia pulcherrima Willd. cv. Eckespoint C-1 Red were exposed to single or repeated episodes of drought stress to leaf water potentials of −1.0 or −1.3 MPa at different times during crop development. Decreased plant height and delayed flowering generally were caused by treatments including stress prior to time of initial bract coloration. Plant quality was reduced by those treatments that inhibited bract development and caused leaf abscission. Inflorescence diameter was reduced the most by stress after bract coloration. Bract dry weight was sensitive to stress and was reduced by stress between the time of initiating long nights and bract coloration. Leaf abscission resulted from a single exposure to −1.3 MPa after flower initiation. Stress prior to start of long nights had little effect on plant development.

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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.

Free access

Jane Whittaker, Terril A. Nell, James E. Barrett, and Thomas J. Sheehan

The effect of postharvest dips on the longevity of Anthurium andraenum cultivar Nitta and Alpinia purpurata was evaluated. The inflorescences were dipped in a 200 ppm benzyladenine (BA) solution, an antitranspirant, or water for 10 minutes. After dipping, anthuriums were placed directly in water and gingers were placed in either water or a 2% sucrose solution and placed in interior conditions (10 μmol m-2s-1 for 12 hr/day, 21±2C). Ginger longevity was increased by 10 days or more by the sucrose solution. The greatest longevity of gingers was obtained when dipped in either BA or the antitranspirant and held in the sucrose solution. Anthurium longevity increased 10 days when dipped in BA, while the other treatments had little effect.

Free access

Jeff B. Million, James E. Barrett, Terril A. Nell, and David G. Clark

A broccoli (Brassica oleracea var. botrytis L.) seedling bioassay was used to measure paclobutrazol activity and distribution in two growing media following drench or subirrigation applications. The bioassay exhibited a saturation-type response curve for paclobutrazol concentrations up to 1000 μg·L-1 in solution and 100 μg·L-1 in the media. The concentration of paclobutrazol required to achieve one-half of the maximum observed bioassay activity was 3-fold as high in bark-based commercial potting medium as in a peat-based medium. Less than 2% of applied paclobutrazol leached out during the drench application despite the collection of up to 50 mL of leachate per 120 mL of the solution (1000 μg·L-1) that was applied per 15-cm pot. Immediately following drench application, paclobutrazol concentrations in both media were highest in the uppermost 2.5 cm and decreased downward. By 3 weeks after treatment, drench-applied paclobutrazol had moved into lower depths. Distribution of paclobutrazol was limited to the bottom 2.5 cm of media when applied as a subirrigation soak. Chemical name used: (±)-(R*,R*)-β-[(4-chlorophenyl)methyl]-α-(1,1-dimethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).

Free access

Richard K. Schoellhorn, James E. Barrett, Carolyn A. Bartuska, and Terril Nell

Effects of heat stress on viable and nonviable axillary meristem development and subsequent lateral branching in 'Improved Mefo' chrysanthemum [Dendranthema ×grandiflorum Ramat. (Kitamura)] were studied. Plants grown at 33 °C day/27 °C night produced more nonviable buds than did plants grown at 23 °C day/18 °C night. A negative linear relationship {y = 28.7 + [-0.66 (x days)], r 2 = 0.70} between timing of exposure to high temperatures and the number of nonviable buds was observed. Histological examination 28 days after exposure to 33 °C/27 °C revealed that plants showed both normal and abnormal bud development. Abnormal bud development occurred as a consequence of premature differentiation of axillary meristematic tissue into nonmeristematic parenchyma tissue immediately after separation of axillary from apical meristems.

Free access

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.