Apical dominance
Under apical dominance the suppression of growth of is side branches by the main engine in plants understood. It is particularly pronounced in plants that grow in the shade of other plants and have a shadow flight.
The primary shoot of the plants is initially formed by the activity of the primary shoot apical meristem (SAM) . Side shoots, also called secondary axes, arise from secondary meristems in the axils of the leaves . After the creation of these secondary meristems, however, their outgrowth into side shoots is often suppressed by the primary shoot tip. This is particularly evident when the primary shoot tip is removed manually. Immediately after removal, the side shoots break their dormancy and start growing.
This effect, sometimes over a greater distance within the plant, is mediated by the plant hormone auxin . Auxin is produced in the tip of the shoot and transported down the plant body. This suppresses side shoot development in the lower part of the plant. After the primary tip of the shoot has been removed, the auxin source is no longer available and the side shoots begin to grow. If an agar block mixed with auxin is used instead of the removed tip of the shoot, the side shoots will not grow out. The other way around, a shoot also begins to grow when the cambium and thus the supply of the auxin z. B. is interrupted by a crescent-shaped cut.
literature
- Apical dominance. In: Gerhard Wagenitz : Dictionary of Botany. Morphology, anatomy, taxonomy, evolution. 2nd, expanded edition. Nikol, Hamburg 2008, ISBN 978-3-937872-94-0 , p. 21.
- Gerhard Friedrich (Ed.): Physiological foundations of fruit growing , p. 30ff, Ulmer Verlag, Stuttgart 2000, ISBN 3-8001-3475-6 .