Inhibits leaf abscission Cytokinins are also formed in the roots and are carried up in a plant stimulating lateral bud growth. The balance of auxin to cytokinin determines the branching pattern of plants. Abscisic Acid is formed in many plant tissues. It is found in fruit, where it prevents seed germination. In buds, it promotes winter dormancy - with bud scales developing to protect the bud.
Abscisic acid helps leaves respond to drought.
When leaves wilt more abscisic acid is produced and the stomata close. It promotes fruit ripening. A tree grown in a field will have a thicker trunk than a tree grown in a forest. The stress from a tree moving in the wind promotes ethylene production, which make the tree wider. The interaction of abscisic acid and ethylene and possibly cytokinins promotes senescence.