NANDANI KUMARI

1. Promotion of cell division: The major physiological role of naturally occurring cytokinins is to promote cell division. It is now well established that these are true cell division factors in a number of lower and higher plants. In the presence of auxins, nearly all cytokinins stimulate cell division and subsequent callus growth in the parenchymatous cells of several plants.

2. Cell enlargement: The cytokinins can also induce cell enlargement like auxins and ...

Cytokinins are mild base growth hormones that promotes cell division.It was discovered by Miler et. Al.(1955).

It was later called kinetin.

Kinetin is an active ingredient obtained from coconut milk and yeast DNA.

Physiological effects of gibberellins are:- 

1. Elongation of intact stems:

Many plants respond to application of GA by a marked increase in stem length; the effect is primarily one of internode elongation.

2. Dwarf shoots:

Besides general increase in stem length, gibberellins specifically induce internodal growth in some genetically dwarf varieties of plants like Pea and Maize. It appears that dwarf- ness of such varieties is due to internal deficiency of gibberellins.

3. Bolting:

...

If planted in spring, winter varieties do not flower or generate mature grains in a span of the flowering season, hence they are cultivated in autumn. Over winter, they sprout and come out as tiny seedlings, resuming growth in the spring and are collected in mid-summer.

b) Vernalisation.

c) Gibberellin.

The important factors affecting the growth of plants include:

1. Temperature.
2. Light.
3. Water.
4. Soil Nutrients.
5. Plant Growth Regulators

 a) Apical buds and shoot tips

 b) Young leaves and root tips

 c) Root tips (meristematic zones).

Apical dominance means that the growing apex of a plant controls the quiescence of buds sitting in lower positions along a shoot. 

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.

The physiological effects of auxins are:-

1. 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  plant hormones are produced by several tissues like the root tips, shoot tips, leaves, meristematic tissues, and apical buds, etc. The presence of vascular tissues like phloem and xylem help in the translocation of hormones to sites of activity.

Auxins are one of the most important plant hormones. These plant hormones are generally produced at the tips of stems and roots. In all vascular plants, auxins play a vital role in:

1. Cell division.
2. Plant propagation.
3. Promoting flowering in plants.
4. Initiation of roots and stem cuttings.
5. Prevent premature dropping of fruits and leaves.

Ethylene, the ripening hormone in plants helps in maturation of sugarcane crops by increasing the storage of sucrose in plants.