AUXINS ; PLANT GROWTH AND MOVEMENT HORMONES
Auxin is phytohormones and the first group of plant hormones.Auxin was discovered by botanist . F.W.Went in 1928 from the tips of Avaena (oat) coleoptiles. On the basis of oat coleoptiles curvature test,he demonstrated that this substance can induce growth .
One of the widespread auxins occurring in plant is Indole -3-acetic acid . ( IAA ). IAA is the principal natural auxin present in the plants. A number of synthetic auxins are :
- Naphthalene acetic acid ( NAA)
- Indole butyric acid ( IBA )
- Indole -3- acetonitrile
- Indole -3- acetaldehyde
- Indole -3-Pyruvic acid
Auxins are synthesized in the root and shoot apices and young leaves . It moves from apex to base by diffusion through phloem .
Role of auxins are :
- Cell elongation
- Apical dominance
- Controlling abscission
- Root initiation
- Cell division in vascular cambium
Uses of auxins are:
- Adventitious root initiation
- Weed control
- Flower initiation
- Thinking of crops
- Inhibition of stem sprouting
- Prevent pre harvest fruit drop
- Root initiation and callus production in tissue culture.