Apical growth refers to the growth that occurs at the tips of a plant’s shoots and roots and is controlled by two phytohormones

• Auxin is responsible for cell elongation and is produced in the shoot tips of a plant

• Cytokinin is responsible for cell division and is produced in the root tips of a plant

Both hormones are required for apical growth and must be transported to the region of the plant where they are not produced

• Auxins are transported from the plant shoots towards the roots (downwards) within the sap of the phloem

• Cytokinin is transported from the plant roots towards the shoots (upwards) within the xylem vessels

Interactions between auxin and cytokinin ensure root and shoot growth is regulated

• Auxins promote root growth and inhibit shoot growth, while cytokinins have the reverse effect (antagonistic)

• Differing the concentrations of the two hormones allows plants to adapt their growth to different environments and nutrient availabilities

Apical Growth Control