BEINGZARA

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2. DIVISION VEGETABLE SCIENCE
TOPIC ON ROLE OF AUXINS IN VEGETABLES
SUBMITTED TO DR. G.M.WANI
SUBMITTED BY WANI BARKAT UL ISLAM
REGISTRATION
NO.
21-HORTI-2014
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3. S/NO TOPIC
Introduction
Types of Auxins
Role of Auxins
Practical applications of Auxins
Commercial applications of Auxins
Auxins use in Horticulture and Agriculture
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4.  First growth hormone to be studied in plants.
 Plays important role in growth and development of
plants.
 Developmental processes like stem elongation,
apical dominance, root intiation, fruit development,
meristem development is controlled by auxin.
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5.  Natural Auxins
 These are naturally occurring in plants. The best
known and universally present natural auxin is Indole
- 3 - acetic acid.
 Other natural auxins are
Indole - 3 - pyuruvic acid,
Indole - 3 - ethanol,
Indole - 3 – acetaldehyde.
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6.  Synthetic Auxins
 These are the chemicals synthesized by chemists that
cause various physiological actions similar to IAA.
 Some of the synthetic auxins are
Indole- 3 - butyric acid (IBA),
napthalene acetic acid (NAA) and
2,4 -dichlorophenoxy acetic acid (2,4 - D).
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7.  Antiauxins
 These are chemicals which inhibit the action
of auxins.
 Examples: 2, 3, 5 triiodobenzoic acid (TIBA)
and napthylthalmic acid (NPA
 Free auxins - are auxins which can be easily
extracted. They are active.
 Bound auxins - are auxins which are difficult
to extract. They are inactive.
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8.  APICAL DOMINANCE
 Removal of apical bud stimulates lateral buds.
 Auxins inhibit lateral bud formation since
they are synthesised in apex. This
phenomena is called apical dominence.
 Cell Division And Elongation: Shoot and
Root growth.
 . Nucleic Acid Activities of IAA increases
total RNA – synthesises specific enzymes
lead to cell enlargement
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9.  Xylem Differentiation:
 Auxins helps in establishing contact
between
vascular tissues of the callus and that of
the bud and makes it possible for the bud
to grow properly in callus.
 By adding auxin and sugar continued
growth of callus may be obtained and new
shoots and even new plant can be
produced.
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10. Manifold Activities Play specific role in
seed germination,
growth,
rooting,
flowering (Reproductive phase),
abscission,
parthenorcarpy and tissue culture.
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11. Seed Germination:
 IAA, IBA, NBA, 2,4-D are mostly used for seed
germination at low concentrations.
 In Tomato pre-sowing seed treatment with 100 ppm
IAA,NAA and IBA enhance seed germination.
 IAA,NAA @20 ppm enhance seed germination in Okra.
 Flowering:
 IAA promotes formation of female flowers in cucurbitis.
 NAA 50ppm has been reported to induce early flowering
in Paprika.
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12. Parthenocarpy:
IBA, NAA produces seedless fruits - smaller sized
fruits, but more in number, hence yield not affected.
 Seed treatment with 2,4D@2-5ppm gives early fruit
set and leads to parthenocarpy in Tomato.
Fruit setting:
IAA, IBA and NAA induce high percentage fruit set.
 NAA @ 10ppm and 2,4-D @ 1-5ppm enhances fruit
set in Tomato,chillies and brinjal.
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13.  . Tissue and Organ culture:
IAA & Kinetin are used in tissue and organ culture.
 Auxins as inhibitors:
High concentration of auxins inhibit the growth and
exert toxic effect on plants. In normal case, self
produced auxins inhibit the growth and development of
lateral buds, and as a result apical buds, remains
dormant.
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14. Rooting:
It is an important technique to reproduce genetically
similar plants. The cuttings are dipped in rooting
powders containing NAA or IBA. This promotes root
initiation and stimulates their development.
 Fruiting:
Naphthalene acetic acid (NAA) and indolebutyric
acid (IBA) help in natural or parthenocarpic fruit
setting that increases crop yield in tomato,pepper,
etc.
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15. Weeding:
2,4-dichlorophenoxyacetic acid (2,4-D) and 2,3,6-
trichlorobenzoic acid (benzoic acid) are used to kill
dicot weeds among the monocot crops as the latter are
unaffected.
Storage:
2-methyl-4-chlorophenoxyacetic acid (MCPA) inhibits
sprouting of buds in potatoes and hence is used in their
storage.
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16. Propagation of plants by hormone treatment of
cuttings.
Increasing parthenocarpy.
 Increasing fruit set.
Prevention of sprouting by inhibiting buds.
Inhibition of prolonged dormancy.
 Control of flowering.
Defoliation of plants
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17. Prevention of leaf fall or abscission.
Thinning of compact fruits.
Selective weed
Prevention of pre harvest drops of plants
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