Removing bark in air layering is done to expose the cambium layer, the site where new roots will develop.
Here's a more detailed explanation:
The process of air layering relies on stimulating a plant to grow roots from a stem while it's still attached to the parent plant. Removing a ring of bark, down to the cambium, is a crucial step. Here's why:
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Exposing the Cambium Layer: The cambium is a thin layer of actively dividing cells located just beneath the bark. These cells are responsible for producing new xylem (water-conducting tissue) and phloem (food-conducting tissue).
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Interrupting Nutrient Flow: Removing the bark (which contains the phloem) disrupts the downward flow of sugars and other nutrients produced by the leaves. These nutrients accumulate above the girdled area (where the bark was removed).
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Stimulating Root Formation: The buildup of sugars and plant hormones in the area above the removed bark promotes the formation of callus tissue (undifferentiated plant cells). Rooting hormones, often applied after bark removal, further encourage these callus cells to differentiate into root cells.
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Creating a Favorable Environment: By wrapping the exposed cambium with a moist rooting medium (like sphagnum moss), a humid and dark environment is created, which is optimal for root development.
In summary, removing the bark is essential for air layering because it exposes the cambium, interrupts nutrient flow, and stimulates root formation at the desired location on the stem.
