Plants contain chemical substances that are responsible for growth, development, reproduction, stress control and many other related activities. These chemical substances are the plant hormones that have single molecules and exist in very moderate quantities. It is also known as phytohormone, which is the organic substance and not any form of active nutrients. Similar to the human and animal hormone, it regulates different activities in the plant cell. These are produced in specific parts of the plants and carried to other parts where it evokes biochemical, psychological and morphological responses. There are mainly five subclasses identified in phytohormones: auxins, gibberellins, cytokinin, abscisic acid and ethylene.
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Auxins and Gibberellins are two major classes of the hormone, which are plant growth regulators. The plant growth regulators are the hormones that manage and control all the aspects related to the plant’s growth and development. Both these hormones impact growth within the plant and take care of the development processes like flowering, root initiation, organogenesis, sex expression, etc. The physiological reactions of auxins and gibberellins show various effects.
Auxin hormones are produced naturally and synthesised artificially within the plants. This hormone is obtained from the amino acid called tryptophan. The term auxin means to enlarge or grow. These are typically located at the growing apices roots, and later it migrates to other parts of the plants to stimulate growth. This hormone has a crucial role to play in the development of the plant.
Gibberellins are a variety of plant and fungal hormones which are acids by the chemical nature. These are a group of hormones that induces plant growth and development. Being a plant growth regulator, it looks after various processes like stem elongation, germination, flowering, enzyme induction, etc. Gibberellins have a dramatic effect on the growth that determines the height of a plant.
The plant hormone auxin can exist naturally, or it can also be processed synthetically. The naturally occurring auxins are indole ethanol, indole acetic acid and indole acetaldehyde.
Synthetic auxins are sometimes used as growth inhibitors and are treated as a herbicide. It includes 2,4-dichlorophenoxyacetic acid indole butyric acid and naphthalene acetic acid.
Q1. What are Cytokinins?
Answer. Cytokinins are the plant hormones that promote cell division and cell differentiation in the plant root and shoot system. These are mostly detected in all thorny plants, and other organisms like mosses, fungi, bacteria and insects. The hormones are mainly produced at the meristem of the roots, and there are around 200 different varieties in both natural and synthetic form. It might promote cell division, but also maintains the level of protein that is essential for mitosis. The process of mitosis helps to replace the damaged cells daily, which further promotes growth. So, it also promotes cell development and growth that affects apical dominance and leaf senescence.
Q2. What are some common uses of Gibberellins?
Answer. Gibberellins are commercially obtained from the fungi that facilitate the quick germination of seeds. Some plants also produce gibberellins, but the quantity is very little compared to the ones obtained from the fungi. It is useful for the farm owners of vineyards as it increases the harvest tremendously. This is because when the gibberellins molecules are sprayed in the vines, it raises the amount of sugar and water content in each fruit. It equally promotes the growth of dwarf species which can be developed quickly by applying gibberellins. In plants like cucumber, gibberellins produce the male flowers that are used to get pollen of desired characteristics.