Auxin Hormone
Auxin means “to grow”. They are mostly used in agricultural and horticultural practices. They are found in the growing apex of roots and stems.
Natural: Indole-3-acetic acid (IAA), Indole butyric acid (IBA)
Synthetic: 2,4-D (2,4-Dichlorophenoxyacetic acid), NAA (Naphthalene acetic acid)
Functions of Auxin :
(i)The elongation of stem and root cells
(ii) IAA in the apical bud inhibits the growth of lateral buds due to apical dominance.
(iii) Causes parthenocarpy, which is the formation of fruit without fertilisation, as in the case of tomatoes.
(iv) Stops the early loss of leaves, flowers, and fruits.
(v) useful for grafting and stem cuttings where it starts the rooting process
(vi) promotes flowering, such as in pineapple
(vii) Extensive use of 2,4-D as a herbicide kills undesirable weeds of dicot plants without damaging monocot plants.