Auxin is a plant growth promoter which is present in shoot and root tip. Ist plant growth regulator to be discovered/ proposed by the biologist Charles Darwin. He observed that, apical shoot tip of seedling show ‘phototropism’. Phototropism means growth of seedlings of plant depend upon the sun sunlight movement. Similarity kind of observation was noted by the Businessman in 1913. He was working on oat coleoptile.
Auxins are two types natural and artificial synthesis auxin. Auxins which is synthesis by plants are known as natural auxin and main term used for these types of auxins are ‘phytohormones’. Mainly, auxin synthesis/ found in shoot and root apical tip and this help to promote cell division. If synthesis of auxin high in the apical part of shoot then it promote cell division which help to increase the height of plant and auxin promote root growth at a low concentration. It is present or synthesis in apical part of shoot and root, developing embryo and fruits. Auxin have a polar movement apex to downward.
IBA, IAA, 2,4-D, NAA, MCPA, 2,4,5-T these are auxins and they use for different purposes these are following: -
1. For Rooting: IBA (indole-3-butyric acid), in micropropagation it is use for root induction. In plant tissue culture micropropagation is a process using small tissue of plant i.e., seed embryo, explant, leaf to grow differentiated or undifferentiated cells. In cuttings IBA play an important role in root induction. For sweat lime cuttings, grape cutting and air layering of jackfruit small and different concentrations for above listed methods of multiplication. Ornamental plants in semi-hard wood and hardwood cuttings IBA works better for root induction. IAA (Indole-3-acetic acid) use for root multiplication and it is naturally occurring plant hormone. It is use in plant tissue culture and loquat air layering, grape cuttings, for better root induction.
2. 2,4-D (2,4-Dichlorophenoxyacetic acid) having dual purposes in agriculture, firstly use in plant tissue culture in callus culture, embryo culture and same other uses like control fruit drop. Secondly, it is use for control weeds in agriculture field, effectively control broad leave weeds same other plant hormones which effectively control weeds these are NAA(Naphthalene acetic acid), MCPA (2-methyl-4-chlorophenoxyacetic acid), 2,4,5-T (2,4,5-Trichlorophenoxyacetic acid).
3. NAA (Naphthalene acetic acid) also widely used in plant tissue for callus induction and in agricultural field it is use to prevent fruit drop.
Same roles of auxin are listed below these are follow: -
i. Prevent/ control fruit drop.
ii. Root and shoot growth.
iii. Cell division.
iv. In plant tissue culture: Auxin play role in callus induction, embryo culture and rooting of explants.
Source: -
- Jitendraa Singh, (2014). Plant growth regulators, Basic of horticulture. Kalyani publishers, pp. 180-189.
- Plant Growth Regulator-Auxin. Link: clinisciences.com
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