levélzáródás

Levélzáródás refers to the phenomenon of leaf abscission in plants, the process by which a plant sheds its leaves. This is a natural and programmed process, typically occurring in deciduous trees and shrubs as a response to changing environmental conditions, most notably the onset of colder temperatures and shorter daylight hours in autumn. The formation of an abscission layer at the base of the petiole (leaf stalk) is a key cellular event. This layer consists of two distinct zones: the abscission zone, where cells weaken and eventually break, and a protective layer, often composed of cork cells, which forms on the stem side to prevent water loss and infection after the leaf has fallen. Hormonal changes play a significant role, with a decrease in auxin and an increase in ethylene triggering the abscission process. While primarily an adaptation to survive winter by conserving water and energy, levélzáródás can also be induced by stress factors such as drought, disease, or physical damage. The shedding of leaves reduces the plant's surface area, minimizing water loss through transpiration during periods when water uptake from the soil might be limited. The process is a vital mechanism for plant survival and seasonal adaptation.