CO2
Benefits for Flowers
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What
factors affect cut flowers?
Temperature:
Temperature is the major factor affecting the storage and vase life
of flowers. This is true for the grower, the shipper, the wholesaler
and the retailer. The sooner the grower can remove the field heat
from the flowers, the longer will be their storage potential (Elgar).
American Floral Endowment sponsored a test with more than 500 temperature
and storage shipping trials between the University of California and
the University of Florida using commercial floral transport trucks
and over 15,000 flowers. The results showed that most fresh cut flowers
must be stored at 33 – 35°F from the time they're cut to
the time they’re placed into a vase (Nell and Reid). (Flowers
freeze at 28°F)
Respiration:
Respiration is the process where the plant’s stored food reserves,
mostly sugars, are broken down to release energy. The energy is used
to maintain healthy cells and tissues. A cut flower has a finite supply
of food reserves. Temperature directly affects the respiration rates
of cut flowers; lowering product temperatures will decrease respiratory
activity, which in turn will slow down the use of stored reserves
and the generation of heat (Elgar).
Ethylene:
Ethylene gas reduces the longevity of some flowers and foliage by
causing rapid wilting of petals (e.g. carnations), shedding or shattering
of petals (e.g. snapdragons, delphiniums), or other changes to petal
tissues, such as loss or change of color (e.g. orchids). Low temperatures
can reduce both the rate of ethylene production and the sensitivity
of flowers to it (Elgar).
Ethylene gas is to plant life what carbon monoxide is to human life:
A colorless, odorless, tasteless gas that kills. Controlling ethylene
is critical in the floral industry. Some studies show that ethylene
is to blame for 30 percent of the industry’s crop losses. Unchecked
ethylene adversely affects how cut flowers perform in consumers’
homes and diminishes their value. (Hoogasian)
Dehydration
and Hydration:
The leaves and petals of flowers have stomata which themselves are
not plant tissue; they are holes! These holes are guarded and sealed
by Guard Cells, one pair per stomata. Together these air-ports make
up 1-2% of the leaf’s area. These cells can expand; sealing
the hole, or contract, opening the hole. Typically stomata shut when
the plant is thirsty, to minimize evapotranspiration, and open when
the plant is well supplied with water. If overheating is a danger,
a well-watered plant will open its stomata to reduce its temperature
by evaporation. (Shaw)
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How
does CO2 help?
Temperature:
CO2 is a refrigerant gas that can help you obtain lower temperatures
in your cooler and save energy. One florist recently said, “No
matter how low I set my thermostat on my cooler, the lowest temperature
I could achieve was 40°F. After I started using CO2 Activ-Pak
in my cooler, I could reach 33°F. The result was phenomenal.”
Respiration:
CO2 gas slows the respiration rate of the flower allowing it to save
its stored food reserves to add in sustaining the plant even after
it has left the florist’s cooler.
Ethylene:
CO2 gas is twice as dense as ethylene gas; therefore it displaces
the ethylene away from the plant and dramatically slows the adverse
affects associated with it.
Dehydration
and Hydration:
CO2 gas is absorbed by the stomata which slows the dehydration process.
CO2 also helps to reduce the bacteria growth in the water buckets
and mold in the cooler in general. Another observed phenomenon is
that the flowers absorb more water than normal
from their water bucket. The result is healthier flowers with better
coloring, more weight, longer vase-life and reduced stem wilting and
petals curling.
Other
Observed Benefits:
Cards left with a bouquet in the cooler overnight no longer get soggy
and bows do not get limp. Flowers last longer, cost of goods decreases
and customers are more satisfied. In one test, roses were kept in
a cooler with CO2 Activ-Pak for 31 days. The roses looked better when
they came out of the cooler then when they went into the cooler. Then
the roses were placed it in a vase on a desk and they lasted another
17 days before needing to be thrown out.
References:
Terril
A. Nell, Ayumi Suzuki, Ria T Leonard, Jim Barrett and Dave Clark Environmental
Horticulture Department University of Florida and Michael Reid and
Linda Dodge, University of California – Davis. Evaluation of
Current Post-Harvest Handling Practices on Imported Fresh Flowers.
http://www.endowment.org/projects/ppr_june99.htm
John Elgar - HortResearch, Mt Albert. Why Cool Flowers?. http://www.hortnet.co.nz/publications/hortfacts/hf305004.htm
Cindy
Hoogasian. Ethylene: A Stealth Destroyer. Floral Management, December
2003. Society of American Florist.
Peter Shaw. Leaves and Flowers.
http://www.shaw39fd.demon.co.uk/plantbiology/lfs.ppt
