1. Cell division
Auxuin helps in initiating and promoting cell division in certain tisues like cambium. When any wound is caused in the plant, the callus is formed to heal the wound. It is formed by proliferation of parenchymatous cells of the wound. Here, the cambial activity is stimulated by auxin.
In tissue culture, cell division entirely depends on the presence of auxins.
2. Shortening of internodes
In certain plantsl ike apple and pear, there arc two types of branches. The fruits arc borne by the dwarf branches caHed spurs. If the terminal shoots are treated with high concentrations of auxins, their elongation is prevented and they become dwarf shoots. These dwart shoots, later bear fruits.
3. Apical dominance
It has been observed that the apical bud grow and the lower axillary buds are suppressed. Removal of the apical bud, immediately, leads to the growth of the lower buds.
This means that auxins of the apical bud inhibit the development of lateral buds and the phenomenen is called apical dominance. If the auxin paste is replaced in the decapitated portion, then again, the activity of the lateral buds is hindered.
It has been further, interpreted that the effect of auxin on the lateral buds is related to the nutritional status of the plant.
4. Flower initiation
Auxins generally prevent flowering. However, in Pineapple, it has been observed auxins promote flowering.
5. Prevention of abscission layer
The abscission layer leads to fall of leaves, flowers and fruits. The auxins are frequently used for the prevention of abscission layer which may sometimes be formed prematurely at the base of petiole, pedicel or peduncle.
6. Root initiation
It has been demonstrated that root forming substance and auxin are identical. The auxin has been found to increase the rate of formation and the number of root initials.
7. Production of parthenocarpic fruits
Fruit that develop even in the absence of pollination and fertilization are called parthenocarpic fruits. The process can be accelerated by application of auxins.