Developing Protocols for Cut Flower Longevity Progress Reports - June 2000
PROJECT PROGRESS REPORT
-
JUNE 1, 2000
Developing Protocols for Cut FIower Longevity
Terril A. Nell, Ayumi Suzuki, Ria T. Leonard, James E.
Barrett, and David G. Clark
Department of Environmental Horticulture
University of Florida, Gainesville FL 32611
and
Michael S. Reid, University of California, Davis, CA.
INDUSTRY NEEDS AND PROJECT OBJECTIVES
Postharvest handling methods that were developed over 20 years ago on
domestically produced flowers arc still current practice in the fresh flower
industry. However, many flowers sold in the U.S. today are imported from
Colombia and Ecuador and can be 8-10 days old when purchased by consumers.
Current problems with cut flower longevity and quality are associated with
shifts in the geographical locations of production. introduction of new
varieties, long-distance transport from farm to consumer, improper transport and
storage temperatures and undesirable handling practices.
The objective of our studies is to improve the performance of cut flowers in
the consumers’ home. To achieve this objective, we are evaluating traditional
handling methods on several cut flower species, storage time and temperature,
and testing new practices such as shipping flowers wet and developing protocols
for treatment with the new anti-ethylene compound, 1-MCP (Ethylbloc).
SUMMARY OF WORK COMPLETED:
I. 1-MCP TREATMENT PROTOCOLS
The newly introduced chemical 1-MCP is an anti-ethylene compound that blocks
the attachment of ethylene to the plant’s ethylene receptor. Cut flowers may
be treated when leaving the farm or wholesaler and potentially be exposed to
ethylene several days later. We tested the effects of this material on a wide
range of cut flower species, and found very beneficial effects in all species
where ethylene has deleterious effects. The 1-MCP proved useful for standard
ethylene-sensitive crops such as larkspur, carnations, snapdragon, alstroemeria,
stock and roses. In addition we found the material to be very effective in
preventing ethylene effects and extending the life of a range of minor and
specialty cut flower crops. Examples include crops as diverse as Anemone,
Bouvardia, Hydrangea, Sunflower, Lavender, Lysimachia, Peony, Phlox, Solidaster,
Sweet pea, and Veronica.
We are continuing to study the interactions among treatment temperature,
treatment time, and 1-MCP treatment concentration on the effectiveness of 1-MCP
NI CP treatment. Warm temperatures (above 70¬?F) allow short treatment times and
lower concentrations. Flowers will respond to 1-MCP if treated at low
temperatures, but at such temperatures longer treatment times and higher 1-MCP
concentrations are required to achieve maximal inhibition of ethylene action. An
example study was designed to determine how long 1-MCP is effective in delaying
or preventing ethylene injury on snapdragons and delphinium. Flowers were
treated with 1-MCP, upon arrival at a temperature of 75 F for 4 hours according
to the product label, then stored at 38¬?F in floral preservative for 0, 3, 6,
9, or 12 days. After storage, flowers were exposed to 1 ppm ethylene for 24
hours and evaluated under consumer conditions. Flowers not treated with 1-MCP
were used as the controls.
A. ‘Potomac Pink’ Snapdragon
Treating with 1-MCP delayed flower senescence 5 to 8 days and promoted
bud development and opening. Flowers were protected from the injurious effects
of ethylene for at least 6 days after 1-MCP was applied. Flowers exposed to
ethylene 9 days or later after the 1-MCP application began to wilt (not abscise)
within 4 days of being placed in the consumer environment compared to 9-11 1
days when exposed earlier. Buds continually developed and opened normally on
1-MCP treated plants. Control flowers (not treated with 1-MCP) showed the normal
abscission and wilting response of snapdragons to ethylene exposure, and the
effects became more pronounced as the flowers were held longer in storage. After
nine days of storage ethylene treatment caused 30% of the flowers to abscise
within 3 days.
B. ‘Belladona’ Delphinium
1-MCP was very effective in preventing abscission up to 9 days after 1-MCP
was applied and all flowers and buds fully opened within 3 days in the consumer
environment. When 1-MCP treated stems were exposed to ethylene 12 days after
1-MCP treatment. abscission occurred within 3 to 4 days. Control flowers showed
the normal response to ethylene exposure. Flowers opened poorly and flower size
was reduced. One to two flowers abscised daily and stems lasted only 5 to 6
days. Flower abscission started to occur in storage conditions after 9 days and
abscission was quicker in the consumer environment.
II. TRANSPORTATION SYSTEMS
The results of our studies on the effects of storage temperature on the vase
life of cut flowers were extended by studying temperatures during commercial
shipments of flowers from California. In a study partially supported by the
California Cut Flower Commission, we demonstrated that flower temperatures
commonly are well above what our AFE-funded research has demonstrated to be
optimal. Laboratory studies also demonstrated that dry storage is as effective
as storage in water, under optimal transportation temperatures.
To evaluate the commercial impact of this finding we conducted a test of the
effects of shipping flowers in a ‘Procona’ shipping container. Three
shipments of ‘Classy’ roses were transported from California to Florida.
Stems were shipped at normal shipping temperatures in a standard cardboard box
dry or in a shipping container (Procona) where stems were upright in water.
Roses that were shipped in the Procona container lasted 3 to 6 days longer.
Flowers shipped dry in a cardboard box had a high incidence of Botrytis’ infection
and most stems had neck rot. Supplying water to flowers during shipment seemed
to keep the flowers fresh compared to the dry box. The structure of the Procona
container with an aerated lid might have promoted air circulation around the
flower heads and prevented Botrytis infection, which resulted in longer
vase life.
III. HYDRATION TRIALS AT RETAIL LEVEL
Stems were either hydrated in Floralife Hydrafi or/100 for 30 minutes or not
hydrated and placed directly into a preservative. Stems were maintained in
consumer conditions of 70¬?F and 70 foot candles.
A. ‘Potomac Pink’ Snapdragon
No benefits in hydrating stems were observed on longevity or leaf quality. In
one experiment, hydrated stems had an increase in flower number. Snapdragons had
an average longevity of 13 days.
B. Pink Gerbera
No benefits in hydrating stems were observed on longevity or flower quality.
In one experiment. stems lasted 2 days longer when not hydrated.
C. Elegance’ Freesia
Flower opening was promoted by hydration treatment and buds opened faster
than non-h hydrated stems but no effects were found on longevity.
D. Liatris
No significant results in hydrated stems were observed . .Stems lasted
approximately 13 days No significant benefits in leaf quality were found, as all
treatments had leaf-yellowing problems.
E. ‘Elite’ Lily
Longevity of the stem was 14 to 17 days. Hydrated stems lasted 3 days longer
compared to non-hydrated sterns.
IV. HYDRATION SOLUTION TEMPERATURE
Postharvest performance was examined after hydrating sterns for 30 minutes in
hydration solutions temperatures maintained at 33¬?F or 110¬?F.
A. ‘Potomac Pink’ Snapdragons
No significant results were found in longevity between treatments. Leaves
wilted severely following warm hydration in one experiment.
B. Pink Gerbera
Stems hydrated at 1 1OF lasted 2 days longer and flowers recovered from stem
bending caused by shipping.
C. ‘Elegance’ Freesia
No significant differences were found between treatments.
V. TYPE OF CUT AND CONTAMINATION OF CUTTING WATER
Bacterial counts in water in the cutting tank were analyzed to determine if
water contamination effects longevity. Stems were cut under fresh deionized
water or cut in the same tank after 100, 200, 300, 400, 500, 600 and 900 flower
stems had been processed. Stems were also cut in the air (dry). Water samples
were collected periodically from the tank and the bacteria number quantified and
analyzed.
A. Water quality
The number of bacteria in the cutting tank water increased dramatically as
the number of stems cut increased. The fresh water in the tank before cutting
sterns had a bacterial count of 6.6×10 cfu/ml. which indicates that even tanks
cleaned with bleach can contain some bacteria. After 300 stems
were cut in the tank. the bacteria count increased to 1 .45x 10 cfu/ml and after
500 stems it had increased to 6.34x 106 cfu/ml it continued to increase from 500
to 900 stems, although the ratio of the increase was not as large as the
increase from fresh water 500 stems.
B. Madame Delbard’ Rose
When roses were cut in the tank after 500 stems had been processed. rose
longevity was significantly reduced (by 3 days!). Also, leaf damage was observed
more when roses were cut at water with a high bacteria count. Roses cut dry (in
air) had the same longevity and quality as roses cut in fresh water.
C. ‘Sheba’ Chrysanthemum
Stems cut in deionized water after 300 stems had been processed had 4 days
shorter vase life (13 days) compared to stems cut in fresh deionized water that
lived for 17 days. Sterns cut in the air had the greatest longevity (20 days).
Leaves of chrysanthemums cut in contaminated water became yellow and dried in 5
to 7 days while leaves of stems Cut in air or cut in fresh water remained turgid
and green.
D. ‘Nelson’ Carnation
In one experiment, cutting in fresh deionized water prolonged longevity of
carnation 2 to 3 days compared to sterns cut in used water but no difference was
observed in a repeat experiment. Flowers cut dry had the same longevity as those
that were cut in fresh deionized water.
E. Pink Gerbera
Longevity was reduced 2 days for flowers cut in water alter 500 stems were
processed in the tank. Cutting diy reduced longevity 2 days compared to cutting
in fresh water.
F. ‘Elegance’ Freesia
Freesia had less sensitivity to water contamination than the other flowers
tested. After 900 sterns were cut, the longevity of freesia was reduced by only
1.5 days. Cutting in air also reduced longevity 1 day compared to cutting under
fresh deionized water.
G. Elite’ Lily
Lily flowers cut under water that had been used to process 300 stems lasted
two days less than those cut under fresh deionized water. Cutting these flowers
in air reduced longevity by 4 days.
H. Snapdragon
No effects of water contamination were observed on snapdragons. Water that
had processed 900 sterns did not affect stem longevity or quality.
VI. EFFECTS OF FLORAL PRESERVATIVE
The longevity of flowers maintained in floral preservative was significantly
greater than that of flowers maintained in deionized water during the consumer
phase. This result was observed in all species tested. For example, longevity
increased 4-8 days for snapdragons, 3-4 days for gerbera, 2 days for freesia, 7
days for liatris, and 5 days for lilies. Also, floral preservative promoted
flower opening for snapdragon, liatris, and freesia, and prevented deformation
of freesia flowers. Clearly, of all procedures tested to date, the use of a
preservative during the consumer phase is the most effective means of increasing
longevity. The effects of sugar (an important component of floral preservatives)
were dramatic in improving opening and color of lisianthus, and preservatives
were found to benefit the postharvest life of a wide variety of specialty cut
flowers.
A common negative effect of sugar-containing preservatives is premature
yellowing of leaves. We have been examining leaf yellowing using a wide variety of
Alstroemeria cultivars. and have demonstrated very significant differences
between cultivars, both in the effects of sugar on yellowing, and in leaf
yellowing in the absence ofpreservative. For many modern cultivars. leaf
yellowing is the first symptom of quality loss, and often occurs while flowers
are still opening. As part of our studies we have developed a new and
inexpensive technique that can be applied at the grower level for delaying leaf
yellowing in cut flowers and potted plants.
FUTURE PLANS
We will continue to conduct studies on the shipping and handling of fresh
flowers at the wholesale/retail/consumer level to determine the primary issues
affecting fresh flower longevity and quality and to develop contemporary
recommendations for improving vase life. We will continue our examination of the
effects of transportation and storage temperatures on flower quality and vase
life. We plan to continue experiments to determine optimal treatment regimes for
the use of 1-MCP treatment. Our research will also explore the influence of
different packing methods and containers on postharvest longevity and quality of
fresh flowers. Domestic fresh flowers will be evaluated in this series of tests
at the University of California and the imported fresh flowers from Colombia
will continue to be evaluated at the University of Florida. Differences in
physiology and quality of Californian and Colombian roses will he compared at
the University of Florida.
