|
From Seed to Community Pot
It takes from six months to one year for a seed capsule to mature. It is not uncommon for a seed capsule to contain 1,000,000 to 3,000,000 seeds. Orchid seeds are transparent and very small. Seeds having the possibility for growth are said to be viable. A viable seed must contain an embryo, but the presence of an embryo is no guarantee of viability. Embryos may be checked by placing seed samples under the microscope.
In "symbiotic germination" or nature's way, fungal infection of protocorm and roots occurs. The required nutrients are provided by the fungus. Growth of seedlings is rapid. From 1850 to 1922, it was the only known method of propagating orchids.
In 1922, Dr. Lewis Knudson of Cornell University provided us with a simpler method called "asymbiotic germination". Seed is germinated and seedlings are grown, without fungi, on a jelly like culture medium which contains sugars and many other nutrients. Today, his formula "C" medium is still being used in laboratories all over the world. Since unwanted bacteria and fungi grow even faster on a sugar rich medium than orchid seedlings, all seeds, flasks, medium and equipment must be sterilized.
Seeding of "Mother Flasks" is done in a sterile environment, such as a laminar flow cabinet in which filtered sterile air is passed over the work area. Seeding of "Mother Flasks" is a simple procedure. Germination medium is prepared and poured into clean flasks. Flasks and medium are then autoclaved for 20 minutes. Cooled flasks are moved into the laminar flow cabinet where sterile seed is placed on top of the medium. Flasks with filter tops are tightly sealed, to keep out micro organisms which would spoil the germination process. Flasks are then placed under florescent lights, on for 12-14 hours per day, except for some genera which germinate in total darkness. After spending two to six month in mother flasks, seedlings are ready for replating.
Replating is the process of moving seedlings from one flask to another flask, inside the laminar flow cabinet. Seedlings are replated when they have reached a stage of growth at which they will greatly benefit from being placed on a fresh and different formula medium. Seedlings now grow very rapidly and usually remain in these flasks for approximately one year, or until they are large enough to be planted out into community pots.
A community pot may hold from fifteen to forty seedlings for approximately one year; they are then transplanted to small individual pots. After several more transplants and lots of tender loving care in the years following, orchid plants reach "flowering size", finally! From seed to flowering orchid plant takes from three to seven years, depending on the orchid species.
Caring for Flasks
It is fun and educational to see orchids grow inside flasks. Flasked seedlings need the right amount of light, temperature and humidity. Handle flasks by grasping them near the bottom, away from the foil covered filtered top. Covered filter tops keep out micro organisms.
Light should be low level, 300 footcandles, gradually increased as seedlings grow bigger. Place them 30cm below two coolwhite fluorescent lamps. Keep lights on, twelve to fourteen hours per day.
Keep temperature in the 75 degrees F (24 degrees C) range, with minimum variation between lights "on" and lights "off" periods.
Flasks have filtered tops allowing air and humidity exchange with the area surrounding the flasks. To prevent the culture medium from drying out, place flasks in an environment where the relative humidity is 50% to 60%. Keep air movement to a minimum. No fans!
Deflasking Seedlings
Seedlings stay in flask close to one year from most recent replate date. Seedlings are removed when leaves are at least three to five cm (one to two inches) long, touch the top of the flask or when the medium is depleted (when you can hardly see it from the mass of roots). They are then deflasked and transplanted to community pots.
Pour some tepid water into the flask and carefully swirl it to break up the agar. A spatula may be used to gently aid the breakup. Pour contents out of the flask into a bowl of tepid water and clean seedlings of all agar. Put into a tepid Benomyl fungicide solution for ten minutes then place them on paper towels to dry.
Preparing Community Pots
Use a well drained, clean pot and line the bottom with drainage material. On top of that fill pot to 3/4 with medium to fine bark. Put a layer of loosely packed wet spagnum moss on top of the bark to within five centimeters (2 inches) from the rim of the pot. Cut sphagnum moss into one cm lengths. Dip gloved hands and tweezer into fungicide bowl. Pick up the largest seedling and place at the back of the pot, roots nestled on top of the sphagnum moss and support it in an upright position. Using tweezers place chopped sphagnum loosely on top of roots and cover them completely. Working from the back of the pot to the front, repeat until the pot is filled. Use extra sphagnum to fill the pot, if necessary.
Taking Care of Community Pot Seedlings
Place community pots 30 cm (12 inches) below two fluorescent lamps, of the coolwhite type, on for 12 to 14 hours per day. Keep day temperatures at about 75 degrees and night temperatures at 70 degrees. Relative humidity of 60% should be provided together with lots of air movement. For the first week mist the seedlings once or twice per day. After one week start a regular watering - fertilizing - misting program. Do not let the medium completely dry out. Balanced, water soluble fertilizers are used at half the recommended strength. As the plants grow bigger, gradually increase the light intensity by placing the seedlings closer to the lamps, tips of the leaves nevr closer than 8 cm. When the seedlings have grown to where the leaf length is 5 to 6 cm, they may be transferred to small individual pots.
Any fine textured growing medium may be used for seedlings, but sphagnum moss is ideal. Sphagnum moss can hold a lot of moisture and at the same time provide excellent aeration for seedling roots. Sphagnum moss holds the seedlings firmly in place and practically eliminates damping-off diseases.
|
|
