How does apical dominance prevent lateral buds from growing?

Apical dominance is the phenomenon where the terminal (leading) bud of a shoot inhibits the growth of lateral, or axillary, buds. This process is primarily regulated by the flow of auxin from the shoot tip, which suppresses the activity of these lateral buds.12

The mechanism involves a complex coordination of hormonal and nutritional factors:

• Hormonal Control: Auxin produced at the shoot apex travels downward, inhibiting the development of axillary shoots. Conversely, cytokinins—substances that promote cell division—can release lateral buds from this inhibition when applied.2
• Nutritional Status: Apical dominance is often strongest when environmental conditions, such as light and mineral supply, are inadequate. The leading bud also acts as a primary sink, absorbing a significant portion of the plant's available nutrients, which further limits the resources available for lateral growth.23
• Dormancy: When the terminal bud is active, lateral buds often enter a state of dormancy. Removing the leading bud eliminates this source of inhibition, allowing the lateral buds to resume growth.23