Terminology use in Apical Dominance

Here are a few terms that will be used in discussing apical dominance. A clear understanding of these terms is needed for understanding the intricate mechanisms of physiological control of branching.

Apical Dominance

The inhibition of growth of lateral buds by the presence of active shoot apex of either the main stem or branches is called apical dominance.

Lateral Buds

Buds which are present in the axils of leaf primordia which are similar to main shoot apex in structure but generally remain dormant.

Dormancy

Arrested condition of growth

Phytohormones

Specific chemical substances that are produced at one site in plants and travel to other areas (targets). At the target they regulate physiological responses.

Shoot Apex

The terminal tissue of main stem or of a branch. Very simple in structure consisting of just two different types of cells which are actively dividing to produce multiple number of cells which differentiate into various structures and tissues of the stem.

Root Apex

The terminal tissue of root consisting of actively dividing cells that differentiate into various tissues of root as the elongation of root takes place. A root apex does not generally give rise to other organs or structures.

Apical dominance can be recognized if we carefully observe the growth of plants. That the shoot apex is responsible for the inhibition of the growth of lateral buds can also be demonstrated "experimentally". You choose any actively growing plants in your courtyard and count the number of branches present immediately below the shoot apex. Take a fine blade and severe the shoot apex. Observe the growth pattern for a period of 10 or 15 days. Count the number of lateral branches sprouting below the cut.