Date 9/3/91

Title of Project Postproduction Longevity of Potted Bulbs

Institution where work is being conducted University of Florida and North Carolina State Univ.

Amount of Endowment Grant $ 11,000
Covering Period 01/01/91 to 12/31/91

Anticipated Date of Project Completion/Final Report December 1993

Individual(s) Conducting Project:

(List Project Leader First)

T.A. Nell - Title Professor

Telephone Number (904) 392-7933

A.A. DeHertogh - Title Professor

J.E. Barrett - Title Professor

Postproduction Longevity of Potted Bulbs

T. A. Nell, A. A. DeHertogh, and J. E. Barrett

University of Florida and North Carolina State University

Progress Report to the American Floral Endowment, 9/3/91

A. Project Objectives:

1. To determine the effective home-life of selected rooting room and non-rooting room forced bulbs

and tuberous flowering potted bulbs.

2. To determine the effect of shipping temperature and duration on longevity and bud drop of potted

Asiatic Lilies.

3. To establish the optimal post-greenhouse light and temperature requirements for forced bulbous plants.

B. Summary of Work Conducted:

1. Effects of ethephon treatments on Amaryllis cv. ‘Cocktail’ and ‘Intokazi’. Bulbs are ordered to

repeat this work in October, November and December 1991.

2. Performance of Caladiums (3 varieties), Asiatic and Oriental Lilies at various interior temperature

and light levels.

3. Evaluation of silver thiosulfate sprays on bud drop and longevity of potted freesia.

4. Response of Asiatic Lilies to simulated shipping times and durations.

C. Results to Date:

1. Forced Amaryllis (Hippeastrum) and Paperwhite

Narcissus plants were shipped in the fall season. Caladiums,

Freesias and Lilies were sent in Spring, 1991. Calla lilies and

Astilbes were forced but could not be sent to the University of

Florida due to excessive disease problems.

2. Ethephon reduced stem height of Amaryllis, but longevity was reduced from 1 to 11 days as a

result of the treatments, depending on time of production and variety.

3. Caladiums performed well for six weeks or longer under interior conditions. Leaf color fading was

a problem on darker leaf varieties but placement of plants into the interior at a more advanced

stage minimized this problem. Few new leaves were produced at any interior temperature or light

level, thus emphasizing the need to market the plants at a mature stage of development.

4. Freesia lasted 15 - 20 days indoors but STS had no effect on any of the varieties tested. It is

possible that earlier applications are needed to obtain positive results.

5. Extended shipping did not affect longevity or performance of lilies indoors provided shipping

temperature was maintained at 35 - 45′F.

D. Future Plans Covered by the Endowment Grant:

1. Amaryllis bulbs are being planted to repeat the studies with Ethephon treatments to reduce stem

elongation.

2. Bulbs have been ordered from Holland for the studies outlined in the current proposal for fall

1991 and winter-spring 1992.

E. Anticipated Benefits for Floral Industry:

Potted bulbs offer the consumer an excellent product for spring holidays and floral sales. These results

illustrate the importance of proper handling and interior conditions. This information should be useful in

floral marketing programs.

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POSTPRODUCTION EVALUATION OF POTTED BULBS

Cooperative Research Project

University of Florida

North Carolina State University

Postproduction research on rooting and non-rooting room bulbs was continued during the

fall of 1990 and spring of 1991 at the University of Florida, Gainesville. Postproduction

evaluations during this period include astilbe, caladiums, growth regulators on amaryllis, silver

thiosulfate applications on freesia, and simulated shipping of lilies. Plants were grown at North

Carolina State University and shipped to the University of Florida at marketable stage. Plants were

boxed and shipped for 3-5 days at temperatures maintained at approximately 42′F.

Postproduction evaluation rooms were maintained at 65, 70 or 75′F at light levels of 50 and 100

ftc. (12 hr/day). Relative humidity was 50% +/- 5%. Results on the postproduction performance

is presented by crop.

I. ASTILBE

Plants were placed directly into postproduction conditions outlined above.

A. Interior Longevity

1. Plants lasted approximately 2 to 3 weeks under postproduction conditions. As

temperature increased from 65 to 75′F, longevity decreased 8 to 16 days for ‘Bumalda’

and 5 to 12 days for ‘Etna’, depending on production time.

2. Plant longevity increased approximately 1 week for both cultivars as light intensity

increased from 50 to 100 ftc.

B. Cultivar Evaluation

1. ‘Bumalda’ and ‘Etna’ cultivars performed similarly at each treatment.

C. Interior Performance

1. At unboxing, flower stalks had a tendency to bend over (2-4 cm) if the top of the box

was restricting.

2. Flower stalks on the average elongated 1 to 2 cm under postproduction conditions.

No significant change in stalk height was observed between cultivars or between

postproduction treatments.

3. Many buds did not develop into flowers when maintained in the postproduction

environment. Both cultivars experienced this problem at all treatments, especially when

maintained at the lower temperature and light level.

II. AMARYLLIS

The growth regulator Ethephon was sprayed on ‘Cocktail’ and ‘Intokazi’ amaryllis in an

attempt to maintain flower stem height control. Ethephon was applied at the following

stages of stem development: 1) stem height of 15 cm; 2) stem height of 25 cm; and 3)

stem height of 15 cm and repeated at 25 cm. Nontreated plants were also included.

Plants were placed into postproduction evaluation rooms maintained at 70′F at a light

intensity of 50 ftc. The experiment was repeated twice.

A. Height Control

1. Stem height. Results of stem height (average of stem 1 and stem 2) measured at the

last open flower of each experiment is presented in Graphs 1 and 2. In each experiment, height was

slightly reduced at each Ethephon treatment compared to control plants. The greatest

height control was obtained when Ethephon was applied twice. ‘Cocktail’ appears to be

more responsive to the growth regulator in each experiment. Although height was reduced

using Ethephon, stems were still very tall and had a tendency to topple over in the

postproduction environment.

2. Leaf height. Results of leaf height measured at the last open flower of each experiment is presented

in Graph 3 and 4. Results were variable within and between experiments. For example,

Ethephon appeared to control leaf height in ‘Cocktail’ when applied twice in experiment 2,

but failed to control height in experiment 1. Inherent variability in leaf development

between plants may play a role in masking Ethephon affects.

B. Longevity

Ethephon treatment reduced longevity up to 11 days when compared to untreated

control plants. Control plants of ‘Intokazi’ lasted 3 weeks while ‘Cocktail’ lasted 2 to 2

1/2 weeks. Longevity was reduced 1 to 7 days in experiment 1 and 3 to 11 days in

experiment 2 on plants treated with Ethephon.

C. Interior Performance and Quality

1. Most buds flowered, regardless of treatment in experiment 2 (Graph 8.), however,

an approximate 26% reduction in number of open flowers was observed in experiment 1

on ‘Cocktail’ when Ethephon was applied either at 15 cm once or twice (15 and 25 cm),

and on ‘Intokazi’ at the 15 cm stem height Ethephon treatment (Graph 7.). Flower size

was not affected by Ethephon.

2. Stem strength, which was evaluated at the first open flower, was categorized as

good’(according to N.C. State rating system) for both cultivars. No differences were

observed between Ethephon treatments. As stems continued to elongate, however, stem

strength progressively became weak and many stems toppled over.

3. Leaf strength, also evaluated at the first open flower, averaged between ‘1′ and ‘2′

(N.C. State rating system) which was the least desirable rating, for all treatments of

‘Inkotazi’, including control plants. ‘Cocktail’ had a better rating, averaging between ‘2′

and ‘3′ for all treatments.

4. An overall quality rating based on the N.C. State system categorized both cultivars

between ‘poor’ and ‘fair’ regardless of treatment. Plants were categorized as ‘poor’ if

plants had very short leaves, 1 stem or plants toppled over, while ‘fair’ plants were those

that had short leaves that were weak and had only 1 stem. Most plants developed 2

stems, therefore, the major factor that contributed to the low quality rating was the

occurrence of stem toppling.

III. Caladiums

Preliminary studies of three cultivars of caladiums ‘Freida Hempel’, ‘Rosebud’

and ‘Candidum Jr.’ were evaluated in postproduction conditions. Plants were kept

in interior conditions for 8 to 10 weeks after which an evaluation was conducted.

A. Interior Performance

1. Freida Hempel.‘Freida Hempel’, a red caladium cultivar, appeared to

do best when maintained

at 65 to 70′F. Plants maintained at these lower temperatures were smaller, but

leaf color was better maintained and did not fade. Plants held at 75′F were taller,

and had greater leaf development, but the red color was faded on new leaves that

developed in rooms.

2. Rosebud. ‘Rosebud’, a pink variety, did best when interior temperatures were maintained

at 65 and 70′F. Although leaf color was better maintained at these lower

temperatures, plants were shorter with less leaf development under interior

conditions. As temperature increased plant height increased and leaf color faded.

3. Candidum Jr. ‘Candidum Jr.’, a white caladium cultivar, did best when interior temperatures

were maintained at 70 and 75′F at a light level of 100 ftc. Plants maintained at

65′F were smaller and had a tendency of leaves to turn a greenish color.

B. Summary

This preliminary evaluation of caladium cultivars indicate that they perform fairly

well under interior conditions for a long period of time. A potential problem is the

fading of leaf color under high interior temperatures and the lack of growth and

development of new leaves under low interior temperatures. Results also indicate

that the stage of development when placed into interior conditions is important.

It is important that plants be of sufficient size when placed in interior conditions

since plant growth is reduced.

IV. FREESIA

Silver thiosulfate (STS) was sprayed on ‘Blue Navy’ and ‘Florida’ freesia in an

attempt to promote flowering. STS was applied at either 2.5 or 5.0 g/liter when

plants were at marketable stage. Nontreated control plants were also included.

A factorial experiment with two cultivars and three rates (0, 2.5, 5.0 g/liter) was

used with five replications of 2 plants each. Plants were placed in postproduction

evaluation rooms maintained at 70′F at a light level of 70 ftc.

A. Flowering

1. Number of Open Flowers.

The number of open flowers of each stem is presented in Graph 1. No

differences in the number of open flowers were observed between control and STS

treated plants. Statistical differences were observed between cultivars only in

stem 1 and stem 2, where ‘Blue Navy’ had a greater number of open flowers.

2. Number of Buds.

The total number of buds of each stem is presented in Graph 2. Differences in

bud number were found between cultivars on each stem. ‘Blue Navy’ averaged 6

to 8 buds per stem, while ‘Florida’ averaged 4 to 6. No differences in bud number

were observed between control plants and STS treated plants.

3. Percent Flower Opening.

Percent flower opening of each stem is presented in Graph 3. No statistical

differences were found between cultivars or STS rates, including control plants.

Generally, both cultivars had between 75% to 80% of flowers open on each stem.

4. Percent Stems that Flowered.

The percentage of stems that flowered is presented in Graph 4. The percentage

of stems that flowered in each cultivar averaged between 90 to nearly 100%. No

differences were found between cultivars or between STS treatments.

B. Interior Longevity

1. Stem Longevity.

Individual stem longevity is presented in Graph 5. Differences in stem longevity

were observed between cultivars in stem 1, 2 and 3 only. ‘Blue Navy’ stems had

an increase in longevity of 1 to 3 days compared to ‘Florida’. No differences in

stem longevity were observed between the three STS rates. A slight decrease in

stem longevity from stem 1 to stem 8 is evident, especially in ‘Blue Navy’ freesia.

This could be related to the fact that fewer buds develop on stems which develop

under interior conditions.

2. Plant Longevity.

Total plant longevity, which was determined from first flower opening until the

last flower died, is presented in Graph 6. No statistical differences were found

between cultivars or STS treatments. These freesia cultivars lasted between 16

to 20 days in interior conditions.

V. Lily

Three cultivars of lilies, ‘Aristocrat’, ‘Polka’ and ‘Horizon’ were boxed and shipped at

35, 45 or 55′F, for 3, 6 or 9 days. Plants were then placed in postproduction rooms

maintained at 70′F at an interior light intensity of 100 ftc.

A. Interior Longevity

1. Aristocrat.

Plant longevity was not significantly affected by shipping treatments. Plant longevity

averaged 12 days for control plants and 11 days for all shipping treatments, excluding

plants shipped at 55′F for 9 days, where longevity averaged 10 days.

2. Polka.

Most treatments, including control plants, lasted 11 to 12 days. Longevity was

reduced to 8 days on plants shipped at 55′F for 9 days.

3. Horizon.

This cultivar lasted 6 to 8 days for both control plants and shipping treatments.

B. Flowering

1. Few flowers opened during shipping when plants were shipped at 35′F and 45′F or

when shipped at 55′F for 3 days. The percentage of flowers that opened after shipping

at 55′F for 9 days averaged 24% for ‘Aristocrat’, 15 % for ‘Horizon’ and 10 % for ‘Polka’.

2. Days to the first open flower, based on when plants were placed into interior rooms

from their shipping treatment, was faster on plants shipped at 55′F.

3. Individual flower longevity, which averaged 4 to 6 days for each cultivar, was not

affected by the shipping treatments.

4. Flower diameters of each cultivar were not affected by shipping treatments.

5. The percentage of flowers that opened for control plants was 96% for ‘Aristocrat’,

85% for ‘Polka’ and only 54% for ‘Horizon’. These averages were similar within each

cultivar when shipped at 35 or 45′F, but were reduced to 63% for ‘Polka’ and 43% for

‘Horizon’ and were the same for ‘Aristocrat’ when shipped at 55′F.

C. Bud Drop

1. Aristocrat.

Bud drop was 2% or less for treatments, including control.

2. Polka.

Bud drop in ‘Polka’ increased as shipping duration and shipping temperature

increased. Bud drop averaged 11% when plants were shipped at 35′F or 45′F for

9 days, and increased up to 23% when shipped at 55′F for 9 days. These

percentages were much higher when compared to a 2% bud drop observed in

control plants.

3. Horizon.

Bud drop averaged 24% in control plants, which was the highest bud drop

observed. Bud drop averaged 4% at shipping temperatures of 35′F, 8% at 45′F

and 10% at 55′F.

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