What is meant by abscission? Name the phytohormone involved in it.

Explanation

**Step-by-Step Solution:**

1. **Definition of Abscission**: Abscission is the biological process in which leaves, flowers, or fruits detach from a plant. This process often occurs before the leaves or fruits have fully matured, leading to their premature fall.

2. **Mechanism of Abscission**: The abscission process involves the formation of an abscission layer, which is a specialized layer of cells at the base of the leaf or fruit stem. This layer acts as a barrier, preventing the flow of water and nutrients to the leaf or fruit, causing it to deteriorate and eventually fall off.

3. **Role of Phytohormones**: The process of abscission is regulated by plant hormones, specifically abscisic acid (ABA). This hormone promotes the formation of the abscission layer and signals the plant to initiate the detachment process.

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