Botany - Plant Growth and Development Question with Solution | TestHub

Gibberellin is a class of plant growth regulators. This hormone was discovered from the fungusGibberella fujikuroi(Class Deuteromycetes), whose perfect stage was assigned to Fusarium moniliforme. This fungus causes Bakanae disease or Bakane foolish seedling disease of rice. This causes rice plants to grow unusually taller, spindle-shaped, pale green in color and production of rice much lesser.
Chemically, gibberellin is gibbane-ring containing complex chemicals with vivid biological activities in plants. There are more than 30 gibberellins known so far. They all are acidic in nature and are called Gibberellic Acid (GA).
The main physiological role of GA includes:
1. Stem and internode elongation. Thus, by applying GA, a genetically dwarf plant can be made into a tall plant.
2. Inducing parthenocarpy for pome type fruits.
3. Help in overcoming natural dormancy in seeds, tubers, rhizomes, etc.
4. Controlling flowering in the long-day plants.
5. Production of male flowers in cannabis like plants.
6. Breakdown of sugar by activation of alpha-amylase in germinating barley seeds, which promotes germination. This is another characteristic property of GAs.

Auxin helps in increased protein synthesis, rhizogenesis, parthenocarpy induction, etc.

Cytokinins are a class of hormones that induce cell division, break apical dominance, expanding leaves, etc.