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After we discuss in part I about the temperature, humidity and nutrition, we will discuss now about light and wather.

Light

Light is not as great of concern as other factors mentioned earlier; however, chronic darkness will cause foliar deterioration. Remember, optimum light levels during production are important to ensure high quality cut flowers.

Water

Plant tissue is comprised mainly of water (at least 95%). Water loss in cut flowers can occur rapidly leading to wilting. Maintaining a low temperature helps to reduce water loss and allows easier rehydration after shipping. Try to prevent any wilting, which will shorten vase life. While it is common to handle flowers dry and rehydrate them later, vase life generally suffers.

Stems will normally accept water as long as the xylem tissues (water conducting channels) are not blocked. Air bubbles may be drawn into the stem at time of harvest, resulting in restricted upward movement of water. Eliminate the blockage by removing an inch of the end of stems under water. Water uptake is enhanced by acidic (pH 3 to 4) and warm (110oF/43oC) water. Microorganisms such as bacteria also plug water conducting channels, necessitating the use of clean containers and solutions which contain germicides.

The lowered pH will also discourage bacterial colonization. Rehydrate wilted flowers in deionized water along with a germicide. Acidify the water with citric acid, 8-HQC (8-hydroxyquinoline citrate) or aluminum sulfate. Do not add sucrose to water when attempting to rehydrate wilted flowers. Rehydrate flowers in a cold room, but begin with water at 110oF/43oC. This same treatment is appropriate for treating non-wilted flowers, except sucrose may be added.

Hard water significantly reduces vase life. However, this can be overcome by deionizing or acidifying the water. Commercial flower preservatives are useful but may not be enough; in cases of very hard or alkaline water, additional acid will be required. High levels of sodium (Na), fluoride (F), or sulfate (SO4) can be toxic. Contact your county educator for help in acquiring a water test to determine salt levels from your water source. This test is inexpensive and will provide information on which to base chemical choice and chemical quantity decisions. Do not use chemically softened water in any stage of cut flower storage.

Ethylene

Flowers generate ethylene gas as a part of the normal aging process. This gas is also given off by several types of ripening fruits, gasoline or propane combustion, and during welding. Air containing 100 parts per billion ethylene (0.00001%) may damage flowers in the vicinity. Thus, a very minute amount can wreak havoc in the storage area. Besides avoiding ethylene producing sources near cut flower production and harvest areas, provide proper air circulation for dilution of the gas. Silver thiosulfate (STS) reduces harmful effects of ethylene and is readily available in various formulations. This product may be recycled and the costly silver recovered. In addition, silver is a heavy metal which pollutes soil and groundwater. SuperCan® is a silver recovery system long used by individuals in the photographic industry. This system allows the silver to be recycled to save money while sparing the environment. Refrigeration also helps to reduce ethylene production and lowers the sensitivity of vulnerable flower species ( Table 2 ).

Flowers listed are particularly sensitive to ethylene.

Agapanthus umbellatus, Freesia hybrids, Alstroemeria hybrids Solidago spp. , Anemone spp. Kniphofia uvaria, Astilbe spp. Lilium spp., Gypsophila spp. Aconitum napellus, Bouvardia hybrids Phlox paniculata, Campanula spp. Scabiosa spp., Dianthus spp. Rosa spp., Centaurea cyanus, Antirrhinum majus, Delphinium spp., Matthiola incana, Dendrobium spp., Lathyrus odoratus, Eremerus robustus. view flowers and plants database.

Geotropism

Geotropism is a growth response to gravity. Unless spikes of flowers such as gladiolus and snapdragon are shipped upright, spikes will bend upward (negative geotropism), causing abnormally shaped flowers. Most flowers, however, can be shipped horizontally.

Next week – Part III – about diseases, insects, storage and direct sale tables.