pruning make it bushier?

Typically a shoot has leaves attached to a stem. The apex of the stem has an actively growing apical bud. It produces additional nodes and internodes to add to the length of the shoot. Additional leaves appear at the nodes as they are produced.

In some plants, the lateral bud located in the axil of each leaf does not grow to form branches, especially at first. This condition is known as strong apical dominance.

Apical dominance is thought to be caused by the apical bud producing IAA (auxin) in abundance. This auxin is transported basipetally from the apical bud. The auxin causes the lateral buds to remain dormant.

When the apical bud is removed, the source of IAA is removed. Since the auxin concentration is much lower, the lateral buds can now grow. In fact their growth will be stimulated by a relativley small drop in auxin concentration (see graph). Thus, decapitating (pruning) a shoot will cause it to branch.