1. EXECUTIVE SUMMARY

Numerous opportunities exist to improve the quality of flowering potted
plant quality and

longevity for consumers. Scientific efforts have demonstrated the importance
of plant genetics and

production practices in maximizing longevity of flowering potted plants.
The majority of the previous

research has been conducted on two or three of the most economically important
crops and no

physiological link has been made to predict the potential longevity of
flowering potted plants. The

basic principles used in development of practices for extending longevity
of flowering potted plants in

the past will serve as the basis for future studies.
It is necessary to investigate the effects of

production practices on longevity on a crop by crop basis. This project
is designed to broaden the

knowledge base related to production and handling factors affecting flowering
potted plants.

Specifically, we will strive to fill the scientific voids in care and handling
information for flowering

potted plants identified in the Kiplinger manual (Nell, 1993) and the SAF/FMA
Grades and Standards

manual. This project will be provide a practical approach
for growers, wholesalers and retailers to

increase flowering potted plant longevity.
2. INTRODUCTION AND LITERATURE REVIEW

Floriculture crops represent 11% of crop agriculture in the United States
with a wholesale value

exceeding $2.8 billion. Over the last 14 years, floriculture sales have
increased 8% each year and has

been the most rapidly expanding segment of crop agriculture in the U.S.
Fower marketing is changing

rapidly as flowering potted plants are transported longer distances and
stored for longer periods during

distribution and sales than in the past two to three decades. Often, plants
are handled improperly

during distribution and sales, especially with increased sales through
mass market outlets. Changes

in marketing have forced significant modifications in production and handling
practices. Research

conducted in our program and at other locations in North America and Europe
have demonstrated the

importance of production and handling practices on flowering potted plant
quality and longevity.

Production conditions must be optimal if plants are to last for consumers.

Flowering plants are in direct competition with a multitude of other discretionary
purchase

items, and if floral sales are to continue increasing, consumers must be
satisfied with the flowers they

buy. In today’s market, florists and mass market buyers are
demanding flowering plants that

demonstrate increased performance, as well as, attractive physical characteristics.
Repeat consumer

purchases are discouraged by plants that fade, wither and die under ordinary
interior conditions.

The potential for flowering potted plant quality and maximum longevity
are determined, to a

large extent, during production. Crop quality must be at the highest level
when the plant leaves the

production facility. Conditions during distribution and retail display
will only maintain plant quality –

plant quality will not increase during distribution and retail facilities.
Quality often declines and

longevity is decreased during transport, storage and retail conditions
as plants are exposed to adverse

transport conditions, such as exclusion of light in closed containers and
sleeves, exposure to harmful

gases and temperature extremes, poor air movement, high humidity, and vibration.

Specific cultural, transportation and interior conditions have been published
for a wide variety

of flowering potted plants (Nell, 1993). Also, grades and standards for
flowering potted plants have

been published by SAF and FMA. However, these publications, grower/retailer
experiences and results

of numerous research experiments demonstrate the voids that exist in the
scientific knowledge about

care and handling of flowering potted plants. In writing the Kiplinger
Manual on Care and Handling of

Flowering Potted Plants, we have tried to achieve the goals of the Kiplinger
Trustees — to provide the

most recent information to all segments of the floriculture industry and
to identify the researchable

areas for future postproduction projects. This project is designed to fill
the voids and assist the

industry in implementation of this information for a wide range of floriculture
crops.

Past accomplishments of the University of Florida Floriculture Postproduction
Program (with

the support of the American Floral Endowment) includes: increasing potted
chrysanthemum longevity

through fertilizer termination and variety selection, reduction and/or
elimination of poinsettia bract edge

burn in poinsettias, development of optimum transport temperatures on numerous
flowering potted

plants, evaluation of fertilizer termination on several flowering potted
plants and evaluation of other

production, handling and retail conditions affecting longevity and quality.
Results of these studies

have appeared in trade magazine articles and industry newsletters on a
regular basis and talks have

been presented at industry short courses throughout the U.S. It is imperative
that the development

of this information continue if growers and retailers are to meet the challenges
of a demanding floral

consumer for a long lasting, high quality flowering potted plant.

All segments of production, handling and marketing influence the longevity
of flowering potted

plants. The importance of production factors becomes evident as each of
the following factors on

longevity are reviewed: genetic influence (cultivar), nutrition, irrigation
practices, growing medium and

production environment. Also, conditions during transport and retail display
can significantly affect

longevity,

Genetic Influence

The importance of genetics in flowering potted plant longevity and quality
is evident with many

plants. Differences range from delayed senescence increased longevity)
to increased tolerances to

low irradiance levels and ethylene exposure.

Longevity of chrysanthemum cultivars having the same flower color and form
varied by as much as

two weeks when produced and maintained similarly. Longevity ranged from
28 days in ‘Iridon’ and

‘Bright Golden Anne’ to 13 days in ‘Tip’ and ‘Mountain Peak’. Similarly,
leaf drop in poinsettia

cultivars ranges from 15% in ‘Eckespoint Lilo’ to 58% in ‘Gross Supjibi’.

Cultivar quality and longevity differences are often associated with interactions
between

cultivar, production environment, plant nutrition or other production related
factors. Longevity of

cyclamen ‘Rose of Aalsmeer’, ‘White Caramel Eye’, ‘Cattleya’, ‘Rose of
Marienthai’ and ‘Pearl of

Zehlendorf’ were greater at production temperatures of 17C compared to
13C (Molinar and Williams,

1977). Termination of fertilizer three weeks prior to flowering increased
longevity in ‘Mountain Peak’

chrysanthemum, a short lasting cultivar, by 7-11 days but longevity of
‘Iridon’, a long lasting cultivar,

increased only 3-5 days.

Nutrition

Nutrition programs may have more impact on flowering potted plant longevity
and quality than

any production factor other than cultivar. The effect is similar to responses
observed with potted

foliage plants (Conover and Poole, 1984) and cut flowers (Halevy and Mayak,
1979) Fertilizer

concentration, fertilizer source and fertilizer type influence plant performance
indoors. Fertilizer type

(slow release, liquid or granular) does not have a significant affect on
longevity or quality provided the

elemental source and balance and concentration applied to the crop are
provided at optimum levels.

In most flowering potted plants, there is a direct response between fertilizer
concentration and

longevity — high fertilizer levels result in decreased longevity. Scott
et al., 1984, demonstrated that

application of Osmocote 14-14-14 at 3g*15cm container decreased leaf drop
in poinsettia compared

to plants receiving 6 go 15 cm pot. Liquid fertilizer applications providing
approximately 2.6 kg*m-3 per

crop are recommended for poinsettias in order to achieve minimal leaf drop.
In chrysanthemums,

Roude et al. (1991 a) showed that longevity averaged 21 days using 5.2
kg*m-3 N per crop from a

soluble fertilizer compared to 34 days using 1.3 kg*m-3 N per crop. These
differences were associated

with growing medium soluble salt concentration. Termination of fertilizer
three weeks prior to

flowering in potted chrysanthemums has been shown to reduce leaf browning
and increase longevity

of chrysanthemums by as much as 7 days (Nell et al., 1989).

Poor nutrition management has been a major factor in the development of
bract edge burn in

poinsettias. Bract edge burn appears as a marginal browning
or necrosis as the bracts expand.

Necrosis may spread to the center of the bracts and render the plants unmarketable.
High fertilizer

concentrations and high ammoniacal-N levels increases the incidence of
bract edge burn. Termination

of fertilizer two to four weeks prior to anthesis did not reduce leaf drop,
but bract edge burn was

reduced significantly (Nell and Barrett, 1986). Woltz and Harbaugh (1966)
demonstrated that calcium

deficiency is the causal factor in bract edge burn. Also, a reduced Ca:K
ratio and low calcium levels

in the bract margins are related to the incidence of bract edge burn (Stromme
et al., 1994). They

found cultivars sensitive to bract edge burn had low calcium levels in
the bract margins while less

sensitive cultivars had high Ca levels.

Apparently, continued fertilization, high nutrient concentrations and high
ammoniacal-N limit

Ca uptake, thus limiting calcium levels necessary for cell development
in the bracts. Incorporation of

supplemental calcium in the growing medium has not reduced the occurrence
of bract edge burn.

However, spray applications of 400 ppm Ca to the bracts weekly beginning
at bract color can eliminate

or greatly reduce bract edge burn (Neil and Barrett, unpublished data).

As with bract edge burn, nutrient balance is important in the production
of high quality, long

lasting flowering potted plants. The ammoniacal-N and nitrate-N levels
must be properly balanced.

Chrysanthemums fertilized with 50% or more nitrate-N

lasted longer than plants having higher levels of ammoniacal-N (Roude et.
al., 1991 b). Changing the

N:K ratio from 1:1 to 0.5:1 during the final four weeks of production has
been emphasized in

chrysanthemum nutrition in the past. Results by Roude et al. (1991 b) suggest
that the N:K ratio may

not be as important as switching to a nitrate based fertilizer near the
end of the crop. The responses

to fertilization may be either a direct result of high medium soluble
salts or elemental toxicity in the

plant. Work in Germany by ter Hell and Hendricks (1995), has demonstrated
a direct relationship

between leaf and cyathia loss in poinsettia and bud drop in rose and impatiens
with increased levels

of nitrogen. They related these results to high soluble salts and reduced
numbers of roots. Reyes

(personal communication, 1996) has demonstrated that medium soluble salt
levels may be responsible

for premature leaf yellowing in chrysanthemum rather than the amount of
nitrogen applied to the

plants.

Growing medium characteristics have an important role in the interior performance
of flowering

potted plants. Longevity increased as N concentration decreased when chrysanthemums
were grown

in metro mix 350, whereas N concentration had no significant effect on
chrysanthemums grown in

Vergro Klay Mix or a peat-perlite-sand mix (Roude et al., 1991 a). Differences
in response to media

type may be related to differences in conductance as affected by high cation
exchange capacity of

Vergro Klay Mix compared to the other media. Thus, correlating medium soluble
salt levels with

longevity must be conducted with each growing medium.

Irrigation practices

Little is known about the relationships between irrigation practices and
longevity, due primarily

to the lack of technology that allows for the monitoring of growing medium
moisture tension in

containers during production. Establishing a well developed root system
is important in the production

of a high quality and long lasting plant. Thus, irrigation practices must
be related directly to the

nutrition program and growing medium soluble salts. Excessive irrigation
will leach excess nutrients

from the medium and could lead to root injury and poor longevity. Conversely,
low irrigation may

result in high medium salt levels and poorly developed root systems if
the nutrient levels are high.

Irrigation and nutrition programs must be coordinated to produce a strong,
functional root system if

maximum longevity is to be achieved. Similar relationships have been demonstrated
for potted foliage

plants (Conover and Poole, 1984).

Proper medium moisture levels for flowering potted plants becomes an issue
in the retail setting

and in interior locations. Increased sales of flowering potted plants through
mass market retailers have

led to increased problems due to poor irrigation of plants during marketing.
Growing media used in

commercial floriculture contain high proportions of peat moss which lose
water rapidly and are difficult

to re-wet once dry. Drying out is a serious problem during retail sales.
Chrysanthemums that were

allowed to wilt before watering lasted 21 days while plants watered prior
to wilt lasted 28 days (Nell

and Barrett, unpublished data). Two approaches have been evaluated as a
means of minimizing the

wilting of plants following production — 1) increasing the growing medium
moisture retention and 2)

reducing leaf moisture loss. Modification of the growing medium by changing
the proportion or type

of components has not led to significant changes in moisture retention
characteristics to have a major

effect on the time to wilt under interior conditions. In many cases, improved
medium moisture

retention characteristics have led to production of plants with increased
leaf area and greater moisture

loss than plants produced in media having less desirable characteristics.
The increased moisture

retention of the medium is not sufficient to counter the effect of increased
transpiration water loss as

a result of increased leaf area. Polyacrylamide gels have been incorporated
into the growing medium

for poinsettias, chrysanthemums and other flowering potted plants as a
means of increasing the

moisture retention of the medium and to delay the time to wilt in retail
settings. Results have been

inconsistent and, generally, no significant benefit has been observed with
the use of gels. Research

has demonstrated a benefit from application of a wetting agent prior to
removal of the plant from the

production area. The wetting agent increases the water holding capacity
of the medium by allowing

for more uniform wetting of the medium at each irrigation. No research
is available to show that

irrigation requirements under interior conditions can be modified through
osmotic adjustment of the

plants during production. Application of antitranspirants have been evaluated
as a means of reducing

moisture loss on several flowering potted plants. Results have been inconsistent
and phytotoxicity has

been apparent on hydrangea and cineraria flowers (Tracey and Lewis, 1981;
McDaniel and Bresenham,

1978).

Production Environment

Production temperature and light levels affect plant size and flower color
and may impact

production quality and longevity significantly. Flower color is enhanced
by lowering the temperature

1 to 2C during the final 1 to 2 weeks of crop production (Nell, 1990).
Research has not been

conducted to demonstrate a reduction in longevity as a result of production
temperature. However,

a number of postproduction problems have been associated with production
temperature, High night

temperatures (relative to day temperatures) increase bract size and lead
to a greater incidence of bract

edge burn and more rapid cyathia drop after plants are moved to interior
conditions (Moe et al., 1992).

Also, high night temperatures increase the level of postproduction leaf
yellowing in Easter lily. The

differences in lily leaf yellowing at different production temperatures
has been related to a reduction

in carbohydrate levels at high night temperatures (Miller et al., 1993).

Lowering the production light level has reduced leaf drop in Ficus benjamina
and other potted

foliage crops (Conover and Poole, 1984). Reduction in light compensation
point has been correlated

with this decreased leaf drop at low light levels. Acclimatization of chrysanthemums
to reduced light

levels also causes a reduction in the light compensation point, but is
of little significance because

longevity is reduced when grown at low light levels (Nell et al., 1990).
These results suggest that the

acclimatization process in flowering potted plants is different from foliage
plants and that light

compensation point is not a useful technique to predict the potential longevity
of flowering potted

plants. Other postproduction problems, such as premature cyathia drop in
poinsettias, has been related to low
production light levels (Miller and Heins, 1986).
3. OBJECTIVES

To identify specific production and handling practices that can be used
to improve quality and increase

longevity of a wide range of flowering potted plants.
4. MATERIALS AND METHODS

Due to the large number of crops that will be grown in this project, specific
crop culture cannot be

provided for each crop. Crop culture will be those recommended for the
crop based on recent

published information or developed through conversations with commercial
growers. The scope of the

work can be best demonstrated in the following table:

Postproduction Research to be conducted at the University of Florida

1996-2000

Crop Cultivar
Fertilizer Fertilizer
Storage Stage of
Interior

Evaluation Rate
Terminatio Duration/
Market- light/temp

n
temperatur ability
erature

e

African
x
x
x
PD
x
x

Violet

Calceolaria x
x
PD
PD
x
x

Cinneraria
x
x
x
x
x
x

Cyclamen
x
x
PD
PD
x
PD

Easter Lily NA
x
C
PD
C
x

Elatior

Begonia
PD
x
PD
PD
x
x

Exacum
x
PD
x
x
x
x

Gerbera

Daisy
x
x
x
x
PD
x

Gloxinia
x
x
x
C
PD
x

Kalanchoe
PD
x
x
PD
x
x

Hibiscus
PD
NA
NA
C
C
PD

Hydrangea
PO
x
C
PD
PD
x

x Research will be conducted as part
of this project. No data are currently available.

PD Preliminary data are available from previous
research in our program or other programs

(only one study conducted). Additonal research required prior to development
of

industry recommendations.

NA Not applicable.

C Work complete. Information currently
in industry recommendations.

For each of the parameters listed above, a series of studies will be conducted
to determine the optimal

production, transport, storage or interior conditions to maximize longevity
or quality. Specific

treatment conditions will vary so greatly with the numerous crops that
it is impossible to provide exact

treatments for each of these crops and studies. The treatment conditions
i.e. temperatures, fertilizer

levels etc. will be based on current recommendations or discussions with
growers. Other crops or

treatments may be added during the course of the project, depending on
needs expressed by industry.
5. LITERATURE CITED

Conover, C.A. and R.T. Poole. 1984. Acclimatization of indoor foliage plants.
Hort. Rev.

6:119-154.

Halevy, A.H. and S. Mayak. 1979. Senescence and postharvest physiology
of cut flowers,

Part 1. Hort. Rev. (1):204-236.

McDaniel, G.L. and G.L. Bresenham. 1978. Use of antitranspirants to improve
water

relations of cineraria. HortScience 13:466-467.

Miller, W.B., P.A. Hammer and T.I. Kirk. 1993. Reversed greenhouse temperatures
alter

carbohydrate status in Lilium longiflorum Thunb. ‘Nellie White’. J. Amer.
Soc. Hort. Sci.

118:736-740.

Miller, S.H. and R.D. Heins. 1986. Variation in cyathia abscission of poinsettia
cultivars in

a greenhouse and a simulated postharvest environment. HortScience 21:270-272.

Moe, R., T. Fjeld and L. M. Mortensen. 1992. Stem elongation and keeping
quality in

poinsettia (euphorbia pulcherrima Willd. ex Klotzsch) as affected by temperature
and

supplementary lighting. Scientia Hortic. 50:127-136.

Molinar, J.M. and C.J. Williams. 1977. Response of Cyclamen persicum cultivars
to different

growing and holding temperatures. Can. J. Plant Sci. 57:93-100.

Nell, T.A. 1990. Lure return customers with flowers that last. GrowerTalks
55(3):45-47.

Nell, T.A. 1993. Flowering potted plants : prolonging shelf life : postproduction
care and

handling. Ball Publishing, Batavia, IL.

Nell, T. A. and J. E. Barrett. 1986. Growth and incidence of bract necrosis
in ‘Gutbier V-14

Glory’ poinsettia. J. Amer. Soc. Hort. Sci. 111:266-269.

Nell, T.A., R.T. Leonard and J.E. Barrett. 1989. Fertilizer termination
influences postharvest

performance of pot chrysanthemum. HortScience 24(6):996-998.

Nell, T.A., R.T. Leonard and J.E. Barrett. 1990. Production and postproduction
irradiance

affects acclimatization and longevity of potted chrysanthemum and poinsettia.
J. Amer. Soc.

Hort. Sci. 115:262-265.

Roude, N., T.A. Nell and J. E. Barrett. 1991 a. Nitrogen source and concentration,
growing

medium, and cultivar affect longevity of potted chrysanthemums. HortScience
26:49-52.

Roude, N., T.A. Nell and J.E. Barrett. 1991b. Longevity of potted chrysanthemums
at

various nitrogen and potassium concentrations and NH4:NO3 ratios. HortScience
26(2):163-

165.

Scott, L.F., T.M. Blessington and J.A. Price. 1984. Influence of controlled
release fertilizers,

storage duration and light source on postharvest quality of poinsettias.
HortScience

19(1):111-112.

Stromme, E., A.R. Selmer-Olsen, H.R. Gislerod and R. Moe. 1994. Cultivar
differences in

nutrient absorption and susceptibility to bract necrosis in poinsettia
(Euphorbia pulcherrima

Willd. ex Klotzsch). Gartenbauwissenschaft 59(1):6-12.

ter Hell, B. and L. Hendricks. 1995. The influence of nitrogen nutrition
on keeping quality of

pot plants. Acta Hort. 405:138-147.

Tracey, T. E. and A.J. Lewis. 1981. Effects of antitranspirants on hydrangea.
HortScience

16:87-89.

Woltz, S. S. and B. K. Harbaugh. 1986. Calcium deficiency as the basic
cause of marginal

bract necrosis of ‘Gutbier V-14 Glory’ poinsettia. HortScience 21:1403-1404.
6. ANNUAL BUDGET

Labor
$18,000

Greenouse suppiies/operation
5,000

Interior room operation
5,000

Total
28,000

7. QUALIFICATIONS

Terril A. Nell, Ria Leonard and Jim Barrett have worked on factors
affecting the

longevity and quality of flowering potted plants for over 15 years. Dave
Clark has recently

joined are floriculture team and will address molecular genetics related
to longevity. The

postproduction facilities at the University of Florida are unmatched in
the United States. We

have 3200 square feet of interior simulation space and 8 coolers for simulation
of storage and

transport conditions. In addition, our greenhouses are less than 7 years
old. These facilities

allow for an integrated approach to postproduction handling through production,
transport and

retail conditions.

This entry was posted on Saturday, June 22nd, 1996 at 9:45 am and is filed under Floricultural Post Production Studies, Research Proposals. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.