Question

Bring out five physiological effects of auxin.

Answer 1

Hint: Auxin is the plant hormone which plays important physiological roles in cell elongation, apical dominance, parthenocarpy etc. It plays an important role in plant life cycles and is essential for plant’s body development.

Complete answer:
Five physiological effects means functional effects of auxin:
> Cell elongation:
Cell elongation is the main function of auxins and these are well known to promote elongation of stem and coleoptiles. It also promotes the growth of the elongation of cells behind the apical meristem. Where the concentration of auxin is higher on the shaded side and it causes the cells on that side to elongate more rapidly which result in bending the stem tip towards the unilateral light.
Auxin elongates the cells by increasing the osmotic solutes of the cell, by reducing the wall pressure and by increasing the permeability of cells to water.

> Apical dominance:
It is seen in mostly tall and sparsely branch vascular plants that if their terminal bud is intact and growing then the growth of the lateral buds just below it remains suppressed. But the removal of apical buds results in their rapid growth i.e., the lateral buds grow super fast. It is called apical dominance since the apical bud dominates over the lateral bud and does not allow the latter to grow. This is called apical dominance.

> Root initiation:
The higher concentration of auxins inhibits the elongation of the root but the later branch roots get continuously increased which means that more the concentration of auxins more will be the growth of lateral branch roots. Root initiation is done by auxins. The application of AA in lanolin paste is of great importance and this is greatly used for the formation of roots in economically useful plants which are propagated by cuttings.

> Vascular differentiation:
In tissue culture experiments it has been confirmed that auxins induce the differentiation in plants. Cytokines are known to participate in vascular differentiation too so it is under control of both auxin and cytokinin.

> Parthenocarpy:
It is the process of development of fruits which fertilisation and these fruits are called as parthenocarpic fruits. Auxin can induce the formation of these fruits. Generally this process is not uncommon and more concentration of auxins are found in ovaries of plants which produce fruits only after fertilisation. In the latter cases, the concentration of auxins increases after pollination and fertilisation.

Note: All these physiological effects of auxins which are really important. All these steps are so easy if you read all of them carefully. None of them can be done without auxin since auxin plays an important role in these physiological functions and it helps in cell differentiation, apical dominance, root initiation, vascular differentiation and parthenocarpy.