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W. Roland Leatherwood, John M. Dole, and James E. Faust

Ethephon [(2-chloroethyl) phosphonic acid] is used to increase stock plant cutting productivity through increased flower and flower bud abscission and branching. However, ethylene evolution resulting from ethephon application is suspected to cause leaf abscission of unrooted cuttings during shipping. It was the objective of this study to assess ethylene evolution from ethephon-treated cuttings during storage and shipping of unrooted cuttings. Impatiens hawkeri W. Bull ‘Sonic Red’ and ‘Sonic White’ stock plants were treated with 0, 250, 500, or 1000 mg·L−1 ethephon. Cuttings were harvested from 1 to 21 days later and each harvest was stored at 20 °C in sealed jars for 24 h before ethylene measurement. Higher ethephon doses resulted in greater ethylene generation. Cuttings harvested 1 day after treatment with 0, 250, 500, or 1000 mg·L−1 ethephon evolved 0.07, 1.3, 1.7, or 5.8 μL·L−1·g−1 (fresh weight) ethylene in the first 24 h of storage at 20 °C, respectively. Twenty-one days after treatment, cuttings from the same plants evolved 0.05, 0.05, 0.15, or 0.14 μL·L−1·g−1 (fresh weight) ethylene in the first 24 h of storage at 20 °C, respectively. As cuttings were harvested from Day 1 to Day 21, ethylene concentrations evolved within the first 24 h of storage decreased exponentially. Rinsing cuttings, treated 24 h earlier with 500 mg·L−1 ethephon, by gently agitating for 10 s in deionized water reduced ethylene evolution to 0.7 μL·L−1·g−1 (fresh weight) as compared with 1.7 for unrinsed cuttings. Cuttings harvested 24 h after treatment with 500 mg·L−1 ethephon stored at 10, 15, 20, and 25 °C for 24 h evolved 0.37, 0.81, 2.03, and 3.55 μL·L−1·g−1 (fresh weight) ethylene. The resulting mean temperature coefficient (Q10) for the 10 to 25 °C range from all replications was 5.15 ± 0.85. Thus, ethylene continues to evolve from ethephon-treated Impatiens hawkeri stock plants for up to 21 days and can accumulate to high concentrations during cutting storage.

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Jaime K. Morvant, John M. Dole, and Janet C. Cole

Pelargonium ×hortorum Bailey `Pinto Red' plants were fertilized with equal amounts of N, P, and K derived from: 1) 100% constant liquid fertilization (CLF); 2) 50% CLF plus 50% controlled-release fertilizer (CRF); or 3) 100% CRF per pot and irrigated using hand (HD), microtube (MT), ebb-and-flow (EF), or capillary mat (CM) irrigation systems. The treatment receiving 100% CRF produced greater total dry weights, and released lower concentrations of NO3-N, NH4-N, and PO4-P in the run-off than the 100% CLF treatment. The percentage of N lost as run-off was greatly reduced with the use of CRF. MT irrigation produced the greatest plant growth and HD irrigation produced the least. The EF system was the most water efficient, with only 4.7% of water lost as run-off. Combining the water-efficient EF system with the nutrient-efficient CRF produced the greatest percentage of N retained by plants and medium (90.7) and the lowest percentage of N lost in the run-off (1.7).

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Uttara C. Samarakoon, James E. Faust, and John M. Dole

Vegetatively propagated unrooted cuttings are typically imported to the United States from Central America. Death or damage of cuttings during shipping and propagation can be reduced if cuttings can be made more resistant to external forces, such as physical damage or pathogen infection. However, strategies to develop durable cuttings via treating stock plants have not been previously quantified in controlled studies. During the current study, mechanical strength of leaves and resistance to infection by Botrytis cinerea were evaluated after weekly applications of calcium chloride (CaCl2) as a foliar spray to stock plants that delivered calcium (Ca) at the concentrations of 0, 400, or 800 mg·L−1. A texture analyzer quantified the peak force required to fracture the leaf and the work of penetration,or area under the force–displacement curve, and these measurements were indicators of mechanical strength. For poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) cuttings at the time of harvest from the stock plant, work of penetration increased by 10% with the application of 800 mg·L−1 Ca compared with the control, whereas peak force by 9%. For zonal geranium (Pelargonium ×hortorum Bailey), work of penetration increased 15% with the application of 800 mg·L−1 Ca compared with the control. Calcium concentration in the leaves increased from 1.2% to 2.0% in geranium and from 1.0% to 1.6% in poinsettia with increasing application from 0 to 800 mg·L−1 Ca. In poinsettia, disease incidence in response to inoculation with B. cinerea spores was 55% and 15% less with CaCl2 applications compared with controls with water and surfactant, respectively, whereas CaCl2 application to geranium did not affect disease incidence.

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Laurence C. Pallez, John M. Dole, and Brian E. Whipker

Days from sowing to anthesis were significantly different among six sunflower (Helianthus annuus L.) cultivars and ranged from 52 days for `Big Smile' to 87 days for `Pacino'. Height ranged from 13.5 cm for `Big Smile' to 37.3 cm for `Pacino'. Postproduction life ranged from 10 days for `Pacino' and `Elf' to 15 days for `Big Smile'. Postproduction quality ratings (1 to 5, with 5 the best) ranged from 3.9 to 5 after 5 days and 1 to 4.2 after 10 days. Quality ratings after 15 days were not significantly different among cultivars, because few plants were marketable at 15 days. Increasing the number of plants per pot from one to three or five reduced number of days to anthesis and postproduction life. Pot sizes of 10-, 13-, or 15-cm diameter, had no influence on production or postproduction characteristics. Promalin (62.5 to 500.0 mg·L–1) was not commercially useful in extending postproduction life. Two cultivars were found to be most suitable for pot production, `Pacino' and `Teddy Bear', with one plant per 15-cm pot and sprayed with B-Nine at 8000 mg·L–1.

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Iftikhar Ahmad, Brian E. Whipker, and John M. Dole

Effects of paclobutrazol and ancymidol on postharvest performance and growth control of potted sunflower (Helianthus annuus L.), zinnia (Zinnia elegans Jacq.) and marigold (Tagetes erecta L.), petunia (Petunia ×hybrida Vilm.) plugs, respectively, were studied. Paclobutrazol was applied as a drench at 0, 1.0, 2.0, or 4.0 mg of a.i. per 15.2-cm pot for sunflower and 0, 0.5, 1.0, or 2.0 mg per 12.5-cm pot for zinnia, while ancymidol was applied at 0, 40, 80, and 160 mg·L−1 with a volume of 0.21 L·m−2 as a foliar spray for marigolds or petunia plug crops. With an increase in paclobutrazol dose or ancymidol concentration, plant growth (plant height and diameter, shoot fresh or dry weight) was controlled for all species tested. Use of 1.0–2.0 mg paclobutrazol per pot produced 21% to 28% shorter plants with 12% to 15% smaller plant diameter, 13% to 19% less shoot fresh weight, 15% to 21% less dry weight, and darker green foliage color for potted sunflower than nontreated plants. Treatment with 1.0–4.0 mg paclobutrazol per pot delayed first wilting by 0.7–1.4 days compared with nontreated plants. For zinnia, 0.5–1.0 mg paclobutrazol controlled plant growth, produced dark green foliage, and extended shelf life by delaying first wilting by 2.6–3.9 days and second wilting by 1.4–2.0 days than nontreated plants. For marigold and petunia plugs, 40–80 mg·L−1 ancymidol provided ample growth control with darker green foliage; however, postharvest longevity was extended only when plugs were sprayed with 160 mg·L−1 ancymidol. During simulated storage and shipping, plant growth retardants maintained darker green foliage for potted sunflower, zinnia, and marigold plugs and prevented postharvest stem elongation of petunia plugs. In summary, use of plant growth retardants effectively controlled excessive plant growth and extended shelf life of potted plants and plugs.

Open access

Cristian E. Loyola, John M. Dole, and Rebecca Dunning

In the United States and Canada, there has been an increase in the demand for local specialty cut flowers and a corresponding increase in production. To assess the needs of the industry, we electronically surveyed 1098 cut flower producers and handlers in the United States and Canada regarding their current cut flower production and postharvest problems, and customer issues. We received a total of 210 responses, resulting in a 19% response rate. The results showed that the main production problem was insect management; crop timing was the second most important problem and disease management was the third. Crop timing encompasses a range of related issues such as determining the correct harvest stage, harvest windows that are too short, flowering all at once, or lack of control when the crop is ready to harvest. The main postharvest problems were temperature management, hydration, and flower food management. Timing and stem length were the two most mentioned species-specific production issues, with each one listed by 10% or more of the respondents for eight of the total 31 species. Regarding on-farm postharvest handling, hydration and vase life were the two most mentioned issues; they were reported for five and three species, respectively. For postharvest during storage and transport, damage and hydration were the most common issues; these were listed for three species each. The most commonly mentioned customer complaints were vase life and shattering, which were reported for six and two species, respectively. These results will allow researchers and businesses to focus on the major cut flower production and postharvest issues and on crops that are most in need of improvement in North America.

Full access

Bridget K. Behe, Paul B. Redman, and John M. Dole

Consumer flower-color preferences are of interest to market researchers, plant producers, and retailers because this information can help them to anticipate accurately the sales product mix. Our objective was to determine consumer bract-color preferences for 47 poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) cultivars. Visitors (124) to the Franklin Park Conservatory in Columbus, Ohio, rated `Sonora', a red cultivar, highest (4.6 of 5.0) of any cultivar. Nine of ten highest rated cultivars were red. We compared the ratings of poinsettia buyers with those of nonpoinsettia buyers and found only one difference: nonpoinsettia buyers rated `Jingle Bells III', a marble cultivar, higher (4.3) than poinsettia buyers (3.8). We also compared consumers who had purchased a red poinsettia to those who had purchased nonred colors and found that red poinsettia buyers rated `Sonora' higher (4.9) than nonred poinsettia buyers (4.5). Men rated `Red Elegance' higher (3.7) than women (3.3), whereas women rated `Freedom White' higher (3.1) than men (2.4). We found few differences between men and women, buyers and nonbuyers, and nonred buyers and red buyers, which may indicate a relatively homogeneous market that does not greatly differentiate among poinsettia bract color.

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Iftikhar Ahmad, John M. Dole, and Bruno T. Favero

Effects of pulsing with different concentrations of gibberellin plus benzyladenine (GA4+7 + BA), a proprietary mixture of GA4+7 plus BA in a commercial floral preservative (GA4+7 + BA + preservative), or a propriety mixture of sugar plus acidifier developed for bulbous flowers (floral bulb preservative) were studied on postharvest performance and quality of cut lily (Lilium hybrids) and gladiolus (Gladiolus hybrids) flowers. Pulsing of cut stems of lily with GA4+7 + BA at 5 or 2 mL·L−1 GA4+7 + BA + preservative for 20 hours at 3 ± 1 °C extended the vase life and controlled leaf chlorosis of ‘Cobra’ oriental lily and ‘Cappuccino’ and ‘Dot Com’ asiatic lily. Cut ‘Orange Art’ asiatic lily performed best when pulsed with GA4+7 + BA at 10 mg·L−1. For cut gladiolus, pulsing with GA4+7 + BA at 10 mg·L−1 extended the vase life of ‘Alice’, ‘Mammoth’, and ‘Passion’, while ‘Scarlet’ had the longest vase life when pulsed with 5 mg·L−1 GA4+7 + BA. GA4+7 + BA + preservative also extended the vase life and controlled leaf chlorosis, but the floral bulb preservative had no effect on vase life extension or preventing leaf chlorosis of lilies. Gladiolus cultivars had no or minor leaf chlorosis during vase period. Overall, overnight pulsing with GA4+7 + BA or GA4+7 + BA + preservative extended the vase life and prevented leaf chlorosis and can be used by growers and wholesalers for maintaining quality of cut stems.

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Iftikhar Ahmad, John M. Dole, Atyab Amjad, and Sagheer Ahmad

Effects of wet and dry storage methods were compared to improve postharvest performance of specialty cut flower species. While increasing duration of storage reduced vase life, vase life declined less with dry storage for marigold (Tagetes erecta) and rose (Rosa hybrida), but not for zinnia (Zinnia elegans) or lisianthus (Eustoma grandiflorum) over wet storage. Marigold stems had 1.9, 4.6, and 1.5 days longer vase life after 1, 2, or 3 weeks in dry storage, respectively, as compared with storage in water. Zinnia stems did not tolerate either wet or dry storage, while lisianthus stems had a longer vase life when stored in water as compared with dry storage. For rose, dry storage for 2 weeks increased vase life compared with wet storage. Dry stored marigold and lisianthus stems had higher water uptake after being placed in the vase as compared with the stems stored in water, while zinnia and rose had less uptake. Storage method had no effect on leaf relative water content (LRWC) in lisianthus, marigold, and zinnia; however, LRWC decreased with increased storage duration. This necessitates evaluation of storage method and duration effects for each species and cultivar to ensure extended storage life and improve postharvest quality.

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Ben A. Bergmann, John M. Dole, and Ingram McCall

Increasing cut stem length and reducing crop production time are producers’ goals for numerous cut flower species. One or both of these aims was met in several field-grown cultivars through foliar application of gibberellic acid (GA3), but effectiveness varied by cultivar, application rate, and timing. Of the 13 cultivars tested, stem length was increased in nine cultivars [Toreador Red celosia (Celosia argentea), Camelot White foxglove (Digitalis purpurea), Imperial Giants Pink Perfection larkspur (Larkspur hybrids), Compliment mix lobelia (Lobelia hybrids), Nippon Taka ornamental pepper (Capsicum annuum), Amazon Neon Duo and Bouquet Purple sweet william (Dianthus hybrids), Summer Pastels yarrow (Achillea millefolium), and Benary’s Giant Scarlet zinnia (Zinnia elegans)], and time to harvest was decreased in four cultivars [High Tide White ageratum (Ageratum houstonianum), lobelia, ornamental pepper, and zinnia], when GA3 was applied as a foliar spray. Concentrations of 400, 800, and 1600 mg·L−1 GA3 were most effective. Application of GA3 resulted in malformed or smaller flowers or lighter green foliage in foxglove, lobelia, sweet william, and zinnia. In most cases, only one application was tested, and greatest response to GA3 was observed during 3–6 weeks post application. Gibberellic acid did not influence stem length in three cultivars [High Tide White ageratum, Aurora Deep Purple delphinium (Delphinium hybrids), and Column Lilac Lavender stock (Matthiola incana)], and decreased flower stem length in one cultivar (High Tide Blue ageratum). Four cultivars were identified as good candidates for further research given their promising responses to GA3 treatments.