STEM PROPAGATION

 

Stem propagation or meristem is the only way to produce exact replica plants of phalaenopsis. I use this method to have back up of some valuable plants. The best stem for propagation is the one that has just opened its first flower. Selected stems are cut and left in a container of water with a drop of physan for a few hours. Meanwhile the laminar flow cabinet is sterilized and the media is prepared. For stem propagation I use media that contains all the hormones and nutrients needed for growth (phytamax orchid multiplecation medium Sigma P6793). As before, the media is sterilized and left in the laminar flow cabinet to gel. Meanwhile I prepare 3 vessels using sterilized water, one with Vircon S (2g to 100 ml), one with saturated solution of calcium hypochlorite (10g to 100 ml and strained through coffee filter paper) or 10% bleach with a drop of Tween 20 or soft soap and the 3rd veasel with 5% bleach.

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Using cotton wool dipped in alcohol, wipe the stem several times from the thicker stem end towards the tip and then leave the stem in the cabinet. With a sharp scalpel, section the stem 1/4 inch above the node and make an angled cut 1" below the node (see picture 1) and keep the stem sections in Vircon's solution. Then take each stem section individually and remove a thin section of the membrane covering the node with very sharp pointed tweezers (see picture 2). Take care not to damage the tissue of the stem. Keep all the sections of the stem in Vircon's solution until you have done them all. When this process has been completed, transfer the stems to a second vessel with 10% bleach (or calcium hypoclorite) to be sterilized for 10-15 minutes, shaking the container vigorously from time to time to ensure good coverage. Remove the stems and cut 1/8" off each end cleanly and put them in a third vessel with 5% bleach. If, however, you prefer more proliferation, insert them in Benzylaminopurine mixture (1g to 100ml alcohol) instead. This, of course, will slightly delay the growth reaction. After about a minute, take each stem out of this vessel with sterilized tweezers and, pushing the diagonally cut end of the stem into the media until the node is level with the surface, plant the stems individually in culture tubes which have been previously prepared ( see picture 3). Seal the tubes and cover them with cling film. Label and store them in a well-lit and warm place in excess of 70 degrees fahrenheit (see picture 5). Keep checking for phenol around the base of the cut. If you see any phenol, replate in fresh media to prevent any toxic build-up.

In about a week you should see the nodes swelling. After a while the growth should yield a rosette of little plant leaves. When they are about 1/4" in size (see picture 4), you transfer them to a larger vessel with a different growing media which includes banana and charcoal powder (Sigma P1056) to finish the growth and encourage a good root system.

After about 12 months, depending on the clone, the young phalaenopsis plants are ready to be deflasked and taken to the greenhouse. From then on treat them as seedlings, keeping them warm and moist until they are well established.



Copyright 1998 C. KOVAC