AIR LAYERING TECHNIQUES

Air layering is technique followed for propagation of plants and shrubs by means of which the emission of roots from a branch is caused. It could be cut and grown as a separate plant with characteristics identical to that of the mother plant. It is generally carried out for acquiring saplings of trees, which are difficult to propagate through other means. However  it is considered to be a more complex process than propagation by seeds or other simpler methods but useful for rooting ornamental plants.

The procedure believed to have originated in China, has spread far and wide, especially after the development of polyethylene film.

The process is to wound or hurt the stem or branch of a plant and enclose the wounded stem with moist sphagnum moss or similar rooting medium until roots develop from the wounded area.

Following are the methods of air layering :

Ring Bark Technique :

Two parallel cuts are made about 1.5 inches apart or two times the diameter of the bark.  Connect the two parallel cuts with one long vertical cut and remove the ring of bark , leaving the inner woody tissue exposed .

A handful of damp sphagnum moss would be applied in such a way that it envelopes the wounded portion of the stem. The moss should be kept in position. The two ends of the polythene film are tied after wrapping the ball of sphagnum around the wound.

After new roots are penetrated the moss ball and are visible on all sides the rooted branch may be removed from the parent plant.  The rooting time will vary with plan variety as well as the season during which it is performed.

Then remove the newly rooted plant from the parent plant with a sharp knife. To ensure that the root system is sufficiently developed to sustain and hold the plant above the new plant could be enclosed in  a polythene tent to prevent excessive loss of moisture.  Once the plant is well established,  it could be gradually exposed to normal atmosphere. A number of plants would be lost during the last stage as the root system may not be able to support the plant. Hence care should be taken to ensure that it does not happen.

 A slight variation of the ring bark technique is making two half ring cuts so that there is half the width of the branch or trunk between the two. The best position is just below a fork.

Skirt Technique :

The first step is to make  a circular cut around the bark with a few vertical slits. Then peel the bark upwards. A metal ring would be pushed up to ensure that the cut portion does not close off.

An idea moss should be used. If a heavy compost, sharp sand, or grit is used its weight will compress, and thus almost certainly damage the brittle roots. If there are a large number of leaves or branches on the newly-rooted air layering, you should remove some of them in order to reduce transpiration until the air layering is properly established.

A slight variation in the  method of wounding plants having less woody stems in preparation for air layering is as follows. This method is usually used on foliage plants such as the rubber plant, With a sharp knife, long upward cut from 1 1/2 to 2 inches long, almost to the center of the stem is made. Insert a wood sliver, toothpick or twisted piece of sphagnum moss into the wound to hold it open and prevent cut tissue from reuniting. At this point, the wounded area may be dusted with one of the commercial rooting compounds to speed up the rooting process. Such compounds, however, do not insure root production on difficult-to-root varieties.