Page 6 - lesson notes-Plant Growth& Movement

Different structures develop in different phases of growth as well as in response to
environment. The ability to change under the influence of internal or external stimuli

is called plasticity. Heterophylly in cotton plant is the example of plasticity.

Plant Growth Regulators are simple molecules of diverse chemical composition which may

be indole compounds, adenine derivatives or derivatives of carotenoids.

Auxin was isolated by F.W. Went from tips of coleoptiles of oat seedlings.

The ‘bakane disease’ of rice seedlings is caused by fungal pathogen Gibberella

fujikuroi. E. Kurosawa found that this disease is caused due to presence of Gibberellin.

Skoog and Miller identified and crystallized the cytokinesis, promoting active
substance called kinetin.

Auxin- was first isolated from human urine. It is commonly indole-3-acetic acid (IAA). It is

generally produced at stem and root apex and migrate to site of action.

Functions-

1. Cell enlargement.

2. Apical dominance

3. Cell division

4. Inhibition of abscission

5. Induce Parthenocarpy

Gibberellins- are promotery PGR found in more than 100 forms named as , ,
…. . The most common one is (Gibberellic Acid).

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