Abscission
/æbˈsɪʒən/
Definition
Abscission is a plant biological process in which a leaf, flower, fruit, seed, or other organ is deliberately shed from the plant. It happens at a specialized separation layer, called the abscission zone, where cells weaken and detach in a controlled way. This differs from accidental breakage because the plant forms the separation point in advance, often as part of normal aging, seasonal leaf drop, or response to stress or damage.
Biological Role
- Seasonal resource management: In many deciduous plants, abscission helps conserve water and energy by shedding leaves before drought or winter, reducing surfaces that lose moisture and need maintenance.
- Fruit and seed timing: Abscission influences reproduction by controlling when flowers, fruits, or seeds detach, which affects seed release, fruit drop, and harvest timing in orchards and gardens.
- Stress and hormone signals: Drought, flooding, cold, injury, and some pathogens can trigger abscission. Plant hormones help regulate this response, especially ethylene, which promotes separation, and auxin, which can delay it.
- Visible clue for diagnosis: Unexpected leaf, bud, or fruit drop can signal stress rather than normal development. In plant care, noticing where and when abscission occurs can help narrow down watering, temperature, or pest problems.
Related Terms
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