Few points to remember about Plant growth Hormones

1. Auxin

• Ist plant hormone to be discovered.
• Chemical structure contains an indole ring.
• Naturally occurring auxin is Indole-3-acetic acid.
• NAA à Synthetic auxin

Movement of Auxin

• Apical to basal end.
• Moves through phloem parenchymatous cells.
• IBA àSynthetic auxin for root initiation.

2. Gibberellin

• Product of fungus Gibberella funjikuroi.
• Kurosawa (1926) from Fusarium moniliformi.

Movement of Gibberellins

• Move radially in all directions.

3. Cytokinin @First King

• First plant cytokinin à Zeatin
• First Cytokinin à Kinetin (Synthetic)

Movement of cytokinin

• Roots to shoots and leaves through xylem.

4. Ethylene

• At anaerobic condition, ethylene formation is completely suppressed.
• Ethylene cause triple response in plant.

a) Inhibition of elongation

b) radial enlargement of tissue (Swelling)

c) Epinastic response

Movement of Ethylene

• Through air spaces ( tissue porosity), through membranes.

Note :

• GA> ABA, Germination proceeds.
• GA< ABA, Germination inhibited.
• ABA promotes dormancy
• Ethylene break dormancy
• Parthenocarpy is produced by NAA and IBA treatment.
• GA induce male flower whereas Ethylene induces female flowers.