Physiological and hormonal Factors Related to Longevity of Flowering Potted Plants Progress Report –March 1991
Date 3/4/91
Title of Project Physiological and Hormonal Factors Affecting Flowering Potted Plant Longevity
Institution where work is being conducted University of Florida
Amount of Endowment Grant $14,500
CoveringPeriod 01/01/91 to 12/31/91
Anticipated Date of Project Completion/Final Report December 1992
Individual(s) Conducting Project:
(List Project Leader First)
T.A. Nell – Title Professor
Telephone Number (904) 392-7933
J.E. Barrett – Title Professor
Physiological and Hormonal Factors Affecting Flowering Potted Plant Longevity
Terril A. Nell and James E. Barrett
University of Florida
- A. Project Objectives:
- 1. To relate physiological parameters (photosynthesis, dark respiration, carbohydrate levels) toincreased longevity of flowering potted plants.
- 2. To evaluate the effects of exogenous growth substances on extending the longevity of floweringpotted plants.
- B. Summary of Work Completed:
- 1. Effect of production temperature (day/night temperatures of 82/72 and 65/75′F) on longevity, budand leaf drop and longevity of potted roses, chrysanthemums and poinsettias.
- 2. Relationship of various physiological parameters to longevity of chrysanthemums.
- C. Results to Date:
- 1. Our current results suggest a minimal effect of production temperature on longevity, as measuredby leaf drop, cyathia drop, flower death and overall appearance. These results will be related to
carbohydrate levels.
- 2. Carbohydrate levels are not providing a clear link to potted plant longevity or to cyathia drop inpoinsettias or bud drop in hibiscus. Fortunately, flower respiration has been identified as an
indicator of flower longevity in chrysanthemums.
- D. Future Plans Covered by the Endowment Grant:
- 1. We are continuing carbohydrate analysis on poinsettias, chrysanthemums and hibiscus todetermine the relationship with longevity.
- 2. Chrysanthemums and roses are being supercharged with sucrose (as in cut flowers) byconnecting the plants to a pediatric intravenous system which provides a 3% sucrose levels into
the stem. It this system works, it will enable us to track carbohydrate levels in the plant more
closely and to understand the significance of commercial practices.
- 3. Continue studies involving effects of production temperature to longevity, bud drop andcarbohydrate levels.
- E. Anticipated Benefits for Floral Industry:
- Cultural practices developed as part of this AFE grant are providing growers with methods toprovide customers with higher quality, longer lasting flowering potted plants. In addition, the current work
with physiological factors affecting longevity provides a long term means of directing breeding programs
and modification of environmental conditions for maximum longevity.
Where are We in Improving Flowering Potted Plant Quality and Longevity?
By: Terril A. Nell and James E. Barrett
- Introduction
- The 1990’s offer unprecedentedopportunities for the
flower production industry in
the U.S., with flower sales in
the U.S. expected to increase
8-9 percent annually between
now and the year 2000. Flowers have been demonstrated to
have positive social, psychological and environmental benefits
for people in their daily lives.
But public interest in plants and
flowers has produced more
sophisticated consumers –
buyers who recognize quality
and have come to expect top
performance products. The
challenge facing the flower
industry is to optimize quality
by carefully controlling not
only production factors, but
also shipping and marketing
environments.
- Consumers in the 90’s wantto purchase plants which will
perform well in a home or
office environment — plants
which will hold on to leaves
and buds under less-than-ideal
conditions, which will retain
their bright flower colors
throughout the blooming
period, and which will survive
reasonably well, even under
adverse conditions. Building a
solid market for flowering
plants means capitalizing on
impulse sales, assuring satisfaction and thereby increasing the
likelihood of repeat purchases.
And all this translates to quality, for disappointed consumers
will not be repeat customers.
- Endowment Sponsored Research at University of Florida
- Commercial growers striveto produce the highest quality
plants with aesthetically
pleasing characteristics (height,
width, flower number, etc.).
However, loss of marketable
product due to production
practices or damage during
handling, transport and storage
is 20% or more. Longevity is
generally determined by 3
factors:
- 1. Plant culture andproduction environment
- 2. Shipping and handlingpractices
- 3. Interior conditions (retailand consumer)
- Successful productiondepends on the grower, while
maintenance of plant quality
may depend directly on the
conditions provided by the
shipper and retailer. Factors
which affect quality and
longevity are: temperature,
light, ethylene, growing
medium, humidity, insects, and
diseases. Careful coordination
among grower, shipper and
retailer is necessary to guarantee
successful production and
delivery of a quality product to
consumer markets.
- Production Practices
- Major advances have beenmade in identifying production
practices which may affect
interior performance of
flowering potted plants, similar
to the success which
accompanies acclimatization of
tropical foliage plants.
Fortunately, increased longevity
can be realized with few, if any,
additional production costs.
However, each flowering
potted plant species must be
handled differently and few
generalizations can be made,
which requires that research
studies must be conducted for
each plant species and, in some
cases, for each variety.
- Table 1. Flowering Potted Plant Longevity.
- Plants were placed under interior conditions providing 800 Lux, 12 hours daily, 20′C (70′F)and 50% relative humidity daily.
| LONGEVITY OF VARIOUS COLORED CHRYSANTHEMUMS | ||||
| BRONZE | LIGHT BRONZE |
RED | WHITE | YELLOW |
| 2 WEEKS | ||||
| Glowing Mandalay | Red Torch | Free Spirit | Dark Yellow Paragon | |
| Torch | Paragon | Sunburst Spirit | ||
| Power House | Tip | |||
| Yellow Mandalay | ||||
| 3 WEEKS | ||||
| Favor | Mandalay | Mountain Snow | Mountain Peak | |
| Mandarin | 24-Karat | Spirit | Sunny Mandalay | |
| Surf | ||||
| Puritan | ||||
| 4 WEEKS | ||||
| Bright Golden Anne | ||||
| Iridon | ||||
- Cultivar Selection.
- Research at the Universityof Florida has evaluated interior
performance of various varieties
of poinsettias, chrysanthemum,
azaleas, potted roses, and
research findings shared with
growers, retailers and
interiorscapers.
- Variety selection candetermine success in terms of
interior performance. Growers
should select cultivars carefully,
not only for case of production
but also for resistance to transit
stress and ability to maintain
superior longevity under
interior conditions. For
instance, the interior longevity
of chrysanthemum cultivars
may vary by as much as two
weeks (Table 1).
- Poinsettia cultivars differ intheir response to handling
procedures; Hegg cultivars
exhibit epinasty after sleeving,
while ‘Gutbier V-14 Glory’
does not (Table 2).
- Also, poinsettia cultivarsdiffer in response to low
interior fight levels (Figure 1).
‘Eckespoint Lilo’ loses less tha
20% of its leaves when placed a
25 ft-c. of light, 12 hours daily
and 70′F while ‘GROSS
SUPJIBI’ loses 66% at the same
light and temperature levels.
Leaf drop of ‘GROSS SUPJIBI’
can be reduced by increasing
the interioer light level to
100 ft-c.
- Longevity of variouscultivars should be considered
in deciding which cultivars to
produce. Some cultivars will
not withstand shipping for long
periods, so they should be used
for local sales only.
- Table 2. The following poinsettia cultivars are susceptible to petiole droop (epinasty).
| Annette Hegg Dark Red |
| Annette Hegg Diva Starlight |
| Annette Hegg Pink |
| Annette Hegg Topwhite |
| Annette Hegg Lady |
| Annette Hegg Marble |
| Peace Cheers! (H-365) |
| Peace Regal Velvet |
| Peace Noel Blush |
| Peace Noel Hot Pink |
| Peace Frost |
| Peace Noel |
- Cultural Practices/Production Environment
- Numerous productionprocedures may influence
longevity, including light,
fertilization practices, produc-
tion mediuml temperature, and
irrigation. Appropriately man-
aging each of these factors can
lead to improved longevity.
- Reduced production lightlevel reduces subsequent leaf
drop of foliage plants indoors,
but low light during the final 3-4 weeks of production has been
related to reduced longevity in
chrysanthemums and premature
cyathia (bud) drop in Hegg
poinsettias. Thus, maintenance
of optimum production light
levels and, possibly the use of
high intensity lighting, may
ultimately improve plant longevity.
- Also, it is clear that fertilization practices have a majoreffect on longevity. Poinsettia
‘Gutbier V-14 Glory’ subjected
to high fertilizer rates from
Osmocote had increased bract
necrosis — a browning of the
bract margins at flowering
(Figure 2). Recommended
Osmocote levels were not
severely damaging. Frequent
irrigation, use of high ammonia
fertilizers and high greenhouse
relative humidities contribute
to this disorder and should be
avoided during production.
- Fertilization practices alsoinfluence chrysanthemum
longevity. Fertilization of
chrysanthemum ‘Mountain
Peak’ to the point of marketing
decreased plant quality and
longevity, compared to discontinuing or terminating fertilizer
at disbudding (approximately 3
weeks prior to marketing).
Longevity of plants was increased 7-12 days when
fertilizer was discontinued (Figure
3). Similar benefits have been
observed on potted azaleas.
Discontinuing or substantially
reducing fertilizer levels during
the second half of the production cycle should prove to be
extremely beneficial.
- Growers often expressconcern about the relationship
of greenhouse temperature to
longevity. Lowering the night
temperature by 3-5′F during
the final 2-3 weeks of chrysanthemum
production will intensify flower color, reduce
greenhouse energy bills and should
lead to increased interior longevity. However, the crop may
be delayed several days by the
lower finishing temperatures.
Research is currently underway
to evaluate the effect of production temperature as part of a
current Endowment-funded
project.
- Shipping and Handling
- Plant quality will notimprove during shipping or
handling! A high quality
flowering plant must be
shipped at the proper
temperature and for the
shortest possible time or quality
will decline and longevity will
be reduced. Darkness, improper
temperature, and the presence
of ethylene during shipping will
significantly affect plant quality.
- Some plants are so sensitiveto darkness that placing plants
into sleeves and boxes for
shipping, regardless of other
shipping conditions, will result
in leaf or flower drop, leaf
yellowing or failure of the
plants to develop properly.
Thus, it is critical that plants
remain in shipping containers
for only brief periods.
- Temperature problemsoccur when plants are exposed
to extreme temperature
conditions — either high or low.
Plants differ in their degree of
sensitivity to temperature, so no
single temperature can be used
for shipping all plant species
without a loss of quality in
some plants. The severity of the
quality loss and the speed with
which it becomes evident will
depend on the plant species.
- For instance, African Violetshipped at temperatures below
50′F will have brown leaves at
unboxing, a symptom of
chilling injury, while Hibiscus
shipped at 35-40′F will appear
uninjured at unboxing but will
lose all buds 3-4 days later. The
delayed bud drop is also a
symptom of chilling injury.
However, the quality and
longevity of still other plants,
such as azaleas and
chrysanthemum, is best
maintained at a 35-40′F
shipping temperature (Table 3).
- Another potential shippingproblem is exposure to
ethylene, a naturally-occurring
plant hormone. Ethylene injury
most commonly appears as leaf
or flower drop, although leaf
yellowing, or leaf and petiole
bending may also result. In
many cases, ethylene exposure
is capable of destroying the
marketability of plants. Injury is
directly proportional to
ethylene concentration, length
of exposure and temperature
during exposure. Damage is
most severe when
concentrations, temperatures
and exposure times are high.
Ethylene injury can often be
minimized or eliminated by
lowering the temperature
(generally to 35-40′F) during
transit. However, this practice is
effective only on plants which
are not sensitive to chilling at
these temperatures.
- Plants which are sensitive toethylene include kalanchoe,
browallia, bougainvillea and
Christmas cactus. The only
effective method to minimize
ethylene injury on plants which
are sensitive to both ethylene
and chilling is to avoid the
presence of ethylene. Some
work has been conducted with
use of silver thiosulfate, a
chemical which prevents the
action of ethylene, but
information is lacking as to
concentration, application times
and effectiveness on a large
number of crops.
- Table 3. Recommended shipping temperatures for flowering potted plants. A check represents recommended temperatures.
| SHIPPING TEMPERATURE | ||
| CROP | 35 to 40′F | 50 to 60′F |
| Amaryllis | x | – |
| African violet | – | x |
| Azalea | x | – |
| Begonia-elatior | – | x |
| Bougainvillea | – | x |
| Browallia | – | x |
| Calceolaria | x | – |
| Christmas cactus | – | x |
| Chrysanthemum | x | – |
| Cineraria | x | – |
| Clereodendron | – | x |
| Crocus | x | – |
| Crossandra | – | x |
| Cyclamen | x | – |
| Cymbidium | – | x |
| Daffodil | x | – |
| Easter cactus | – | x |
| Easter lily | x | – |
| Exacum | – | x |
| Freesia | x | – |
| Gloxinia | – | x |
| Grape hyacinth | x | – |
| Hibiscus | – | x |
| Hyacinth | x | – |
| Hydrangea | x | – |
| Kalanchoe | x | – |
| Oxalis | x | – |
| Poinsettia | – | x |
| Regal geranium | x | – |
| Rose | x | – |
| Streptocarpus | – | x |
| Tulip | x | – |
- Adapted from information by E.P. Stuling and W.H. Molenaar, Report No. 2286, Springe Institute, Wageringen, the Netherlands,
and T.A Nell. Flowering plants for interiors. Copyright 1990
GrowerTalks magazine. Reprinted with permission.
- Retail Conditions
- High quality plants can bedestroyed or longevity rapidly
diminished if not maintained
properly at retail stores. Low
display light levels may cause
leaf drop and yellowing, bud
drop and premature and rapid
aging of flowering plants.
Generally, results indicate that
flowering plants require higher
light levels during display than
foliage plants and that the light
level depends on interior
temperature. Also, interior light
level varies among flowering
potted plant species (Figure 4).
- Conclusion
- Educated consumers areincreasingly demanding
flowering plants which maintain
high quality characteristics over
a reasonable period of time,
even when placed in less-than-ideal conditions. The challenge
facing the flower industry in the
1990’s is to optimize quality by
carefully controlling not only
production factors, but also
shipping and marketing
environments. Endowment
research is proving that optimal
quality can be achieved.
However, a coordinated effort
will be required to capitalize
the market opportunities in the
decade ahead.
- Anyone desiring more information may write
Dr. Terril Nell or Dr. James
Barrett at the address below:
- University of Florida
- Ornamental Horticulture Department
- 1505 Fifield Hall
- Gainesville, Florida 32611
- The Endowment began supporting University of
Florida research on flowering
potted plant quality and
longevity in 1985. During
thelast 5-6 years the
program has studied
production, shipping and
retail factors affecting the life
and interior performance of
numerous flowering potted
plants. Results led to
recommendations for
growers, Shippers and retailers
to improve flowering potted
plant longevity, some of
which will be discussed in
this update on care and
handling procedures.
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