economic importance of plant growth...
TRANSCRIPT
Economic Importance of Plant Growth Regulators
Table of Contents
Introductionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip2
Plant growth regulatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip3
Auxin and it economic importancehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip3-6
Gibberellins and its economic importancehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip6-8
Cytokinins and its economic importancehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip8-9
Abscissic Acid and its economic importancehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip10
Ethylene and its economic importancehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip10-11
Other hormoneshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip12
Conclusionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip13
Referenceshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip14
Page 1 of 15
Economic Importance of Plant Growth Regulators
Introduction
According to Devlin and Witham (1986) ldquoplant growth regulators are organic
compounds other than nutrients that in small amounts promote inhibit or otherwise modify a
physiological process in plants Plant hormones or phytohormones are regulators produced by
plants in which a low concentration regulates plant physiological processesrdquo (p 354) The
growth regulators can either be natural or synthetic and are widely being used in the agricultural
production and even for economic importance
The plant growth regulators have various economic importances in agricultural field
Their importance has been boon and advantages for farmers and horticulturists They took
advantage to earn by the practical implication and implication of these hormones and growth
regulators The very assignment mainly comprises of economic importance of plant growth
regulators
The plant growth regulators primarily include auxin gibberellin cytokinin
ethylene and abscisic acid (ABA) Secondarily it also includes florigens anthesin
vernalin morphactins etc Each growth regulators have various role and functions
which contributes to economic of the farmers and horticulturists worldwide
This assignment basically contains economic importance of each growth
regulator with different uses and practical application in agriculture and horticulture
For example auxins are used to increase fruit-sets control flowering etc Gibberellins
is used to increase sugar content in sugarcane etc Similarly every hormone posses different role
and economic importance where this very assignment mainly discusses as below
Page 2 of 15
Economic Importance of Plant Growth Regulators
Plant growth regulators Plant hormones Phytohormones
Plant hormones and growth regulators are chemicals that affect flowering aging root
growth distortion and killing of leaves stems and other parts prevention or promotion of stem
elongation etc
Rastogi (2011) defined that the plant growth regulator or phytohormone as an organic
substance produced naturally in plants controlling growth and other functions at a site remote
from its place of production in minute quantities Philips as cited in Pandey and Sinha (2006)
defined growth hormones as substances which are synthesized and transferred to other cells
where in extremely small quantities influence the developmental processes The growth
regulators can either be growth promoters or inhibitors A plant growth regulator is also an
organic compound either natural or synthetic that modifies or controls one or more specific
physiological processes within a plant through translocation And they can be either synthetic or
natural The growth regulators include
1 Auxins
2 Gibberellins
3 Cytokinins
4 Ethylene
5 Abscisic acid
6 Flowering hormones
7 Florigen Anthesins Vernalin Morphactinsetc
But major plant growth regulators are first five ones and are discussed as follows
1 Auxins
It is the plant growth regulators that mainly help in rooting besides its minor functions
This growth substance was found out by Charles Darwin in his book called The Power of
Movement of Plants He demonstrated that apical tips of seedlings are sensitive to unilateral
illumination and positive phototropism He concluded that the tip senses the unilateral light
stimulus but the curvature occurs down as a result of more rapid growth on the shaded than
illuminated side of the coleoptiles And he also noted that when the tip of coleoptiles was excised
Page 3 of 15
Economic Importance of Plant Growth Regulators
no curvature response occurred Therefore he said that when seedlings are freely exposed to
lateral light some influence is transmitted from the upper to lower part causing the later bent
Similar observations were made by Boysen-Jensen (1913) and Went (1928) They too did
and demonstrated on coleoptiles
Characteristics
1 Polar translocation- movement from apex to downward
2 Apical bud dominance
3 Variable behavior root and shoot growth
4 Root initiation
5 Belay in abscission
There are many different natural and synthetic auxins with different functions
1 Indole acetic acid-IAA
2 Indolebutyrib acid=IBA
3 Napthalene acetic acid-NAA
4 24-dichlorophenoxy acetic acid-24-D
Role of Auxin
The following are some of the responses that auxin is known to cause as cited by Davies 1995
Mauseth 1991 Raven 1992 Salisbury and Ross 1992
Stimulates cell elongation
Stimulates cell division in the cambium and in combination with cytokinins in tissue
culture
Stimulates differentiation of phloem and xylem
Stimulates root initiation on stem cuttings and lateral root development in tissue culture
Mediates the tropistic response of bending in response to gravity and light
The auxin supply from the apical bud suppresses growth of lateral buds
Page 4 of 15
Economic Importance of Plant Growth Regulators
Can induce fruit setting and growth in some plants
Delays fruit ripening
Promotes flowering
Stimulates growth of flower parts
Promotes femaleness in dioecious flowers
Stimulates the production of ethylene at high concentrations
Practical Application and its economic importance
1 Germination IAA IBA NPA 2 4-D are widely used to soak seeds for
germinationAuxins are widely used to break the dormancy of the seeds The pre-
treatment of seeds before sowing with IAA IBA 2 4-D etc found to have increased the
length of the hypocotyls at low concentration and shortening at higher concentration
Bhardwaj and Rao as cited in Pandey and Sinha (2006) reported that the effect of 24-D
on the growth and maturity of wheat and recorded 33 increased at 10 ppm treatment
Auxins can have very effective effects at very low concentration The higher concentration
and prolonged treatment retard and reduce germination
2 Rooting NAA and IBA are used for inducing the rooting of cuttings of woody plants
Malik and Chhonker as cited in Pandey and Sinha (2006) studied that the rooting effects
of different auxins and found out that the treatment of IBA and IAA are more superiors as
compared to other auxin type The effect of auxin NAA on mango varieties too has the
importance as a 10 induces 100 rooting
3 Flowering Hitchcock and Zimnermann as cited in Pandey and Sinha (2006) showed that
the even a minute quantity of auxins accelerated the flowering It is also reported that
IAA promotes the formation female flowers The application of auxins also helps to
increase the yield and flowering of wheat Das and Singh (1958) also studied the effect of
auxin IAA on flowering and fruiting in pineapple NAA and 2 4-D to induce flowering
in litchi and pineapple
4 ParthenocarpyIt is produced mainly by NAA and IBA Treatment of NAA in cucumber
and melon fruits produce seedless fruits (Das 1962)
Page 5 of 15
Economic Importance of Plant Growth Regulators
5 Weeds controlThey are selective weeds killers and considerably used in the destruction
of weds in crop fields rail-roads lawns and forests Common weedicides of auxin in
nature includes 2 4-D and 2 4 5-T etc
In Agriculture and Horticulture
Auxins are used for
1 Propagation of plants by hormone treatment in cuttings scions
2 Prevention of pre-harvest drop of fruits
3 Increasing parthenocarpy
4 Increasing fruit-sets
5 Inhibition of prolonged dormancy
6 Control of flowering
7 Defoliation of plants
8 Prevention of leaf falls or abscission
9 Selective weed killers
2 Gibberellins
It is the second major plant hormones which is mainly functional for shoot proliferation
besides flowering and breaking of seed dormancy It was first known by a Japneses farmer
Konishi (1898) and working was found out by Kurosawa in 1926 He discovered as GA It was
first extracted from the ascomycetous fungus GibberellaFujikuroi the casual organisms of
ldquofoolish seedling of ricerdquo or commonly called bakanae of rice The infected plants were taller
seedless and pale in colour These symptoms were produced due the substances secreted by the
fungus
It is mainly of gibberrelinGA3 or A3
Characteristics
1 Prevention of genetic and physiological dwarfism
2 Breaking of dormancy
3 Induction of flowering long day plants
Page 6 of 15
Economic Importance of Plant Growth Regulators
4 Increase amylase activity and
5 Substitute for chilling effects
Role of gibberellins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulate stem elongation by stimulating cell division and elongation
Stimulates boltingflowering in response to long days
Breaks seed dormancy in some plants which require stratification or light to induce
germination
Stimulates enzyme production -amylase in germinating cereal grains for mobilization of
seed reserves
Induces maleness in dioecious flowers (sex expression)
Can cause parthenocarpic fruit development
Can delay senescence in leaves and citrus fruits
Practical Application and its economic importance
1 Germination It has been widely used for germination experiments GA is found to
increase the length of hypocotyls and cotyledonary leaf (Chakravarti 1958) GA also has
important role in seed germination of cereals
2 Rooting Various experiments have suggested that the gibberellins have effect on
rooting Kato (1958) reported that it not only root initiation is inhibited but also the
stimulation of rooting by the auxin is also counteracted
3 Flowering GA induces flowering in long day plants and in plants requiring inductive
cold period It also promotes the formation of male flowers as it plays important role in
development of male flower
4 Parthenocarpy Mukerje and Dutta as cited in Pandey and Sinha (2006) have found out
that GA induces the formation of parthenocarpic fruits in brinjal It can also be done in
guava to produce parthenocarpic fruits It is also used to induce the parthenocarpy in
pome fruits and use to increase the fruit size and bunch length in grapes as well
Page 7 of 15
Economic Importance of Plant Growth Regulators
5 Fruit Setting GA affects more positively on fruit setting Randhaw and Singh (1959)
observed an increase in fruit setting in seedless grapes an increased in fruit size fruit set
total yield and quality in sweet lime have also been due to the treatment of GA
GAs is used to increase the size of Thompson grapes berries It is used by some breweries to
increase the rate of malting by increasing the potential of starch digestion Gibberellins are also
use to increase sugar cane growth and sugar yields
It posses great uses in increasing stalk length and production breaking of dormancy
inducing uniform crop emergence producing staminate flowers loosening of fruit clusters
increasing the fruit size quickening of maturity improving fruit quality controlling cracking of
fruits reducing non-productive period promoting vegetative growth and flower size increasing
sugar content in sugar cane inducing flowering and so on
3 Cytokinins
Skoog (1964) noted that in general ldquothe term Cytokinin is universally used for substance
which promotes cell division and exerts other growth regulatory functions as kinetinrdquo It also
promotes cell division and influence cell differentiation and aging of leaves
Characteristics
1 Initiation of cell division
2 Delay of senescence
3 Use of tissue culture
4 Counteract apical dominance
5 Induces flowering short day plants
Page 8 of 15
Economic Importance of Plant Growth Regulators
Role of Cytokinins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulates cell division
Stimulates morphogenesis -shoot initiationbud formation in tissue culture
Stimulates the growth of lateral buds-release of apical dominance
Stimulates leaf expansion resulting from cell enlargement
May enhance stomata opening in some species
Practical Application and its economic importance
1 Cell division Braun and Wood (1962) demonstrated that on exogenous supply of
cytokinin a normal Vinca cell converts to a turmour cell Skoog also showed that IAA
alone produces few mitoses in tobacco pith tissue but kinetinin combination with IAA
induces more mitoses This hormone never acts alone but in association or combination
with hormones like auxins cytokinins etc
2 Cell enlargement Scot and Liverman as cited in Pandey and Sinha (2006) reported the
property of cell enlargement in the disc of etiolated leaf by cytokinin Similar results
were also made in tobacco pith and cortical cells of tobacco roots
3 Dormancy It ahs been found quite effective in breaking the dormancy of the seeds and
other plant organ
4 Apical dominance Wickson and Thimann (1958) found that this hormone counteract
the usual apical dominace of bud These hormones have also been reported to induce the
lateral bud formation which is apparently related to the vascular tissue differentiation
The major use for cytokinins derives from its ability to delay senescence and maintain
greenness The artificial highly active cytokinin benzyladenine is the main compound used
The treatment of holly for festive decorations enables its harvest many weeks prior to use Post-
harvest sprays are now available to prolong the storage life of green vegetables such as
asparagus broccoli and celery
Page 9 of 15
Economic Importance of Plant Growth Regulators
These hormones also have used to increase shelf life of fruits quickening of root induction
and production of efficient root system It is also used to increase the yield and oil contents in
ground nuts to break the dormancy delay senescence causes cell division and so on
4 Abscissic Acid( ABA)
It is regarded as one of the principal accelerators of abscission and also bud dormancy It is
natural growth inhibitors and acts as a stress hormone that helps to cope with adverse
environmental conditions
Role of Abscissic Acid
A list of some of the known physiological effects caused by cytokinins is listed below
(Davies 1995 Mauseth 1991 Raven 1992 Salisbury and Ross 1992)
Stimulates the closure of stomata-water stress brings about an increase in ABA synthesis
Inhibits shoot growth but will not have as much affect on roots or may even promote
growth of roots
Induces seeds to synthesize storage proteins
Inhibits the affect of gibberellins on stimulating
Has some effect on induction and maintenance of dormancy
Induces gene transcription especially for proteinase inhibitors in response to wounding
which may explain an apparent role in pathogen defense
5 Ethylene
The only ripening hormone Denny as cited in Pandey and Sinha (2006) reported that
ethylene is highly effective in fruits ripening It is actually the natural product of ripening fruits
It is a gas at temperature under which a plant can survive It is a powerful inhibitor of root and
stem elongation
Page 10 of 15
Economic Importance of Plant Growth Regulators
Role of Ehtylene
Ethylene is known to affect the following plant processes (Davies 1995 Mauseth 1991
Raven 1992 Salisbury and Ross 1992)
Stimulates the release of dormancy
Stimulates shoot and root growth and differentiation (triple response)
May have a role in adventitious root formation
Stimulates leaf and fruit abscission
Stimulates Bromiliad flower induction
Induction of femaleness in dioecious flowers
Stimulates flower opening
Stimulates flower and leaf senescence
Stimulates fruit ripening
Practical Application and its economic importance
Ethylene gas a wide variety of uses but its gaseous nature precludes its applications in
non-enclosed spaces Ethylene itself can be used to enhance the ripening of fruits such as
bananas in storage following their shipment in an unripe condition An ethylene-producing liquid
chemical 2-chloroethylphosphonic acid - commercially called Ethrel or Ethephon has been
introduced and it is sprayed onto the plant at a slightly acid pH When it enters the cells and
encounters the cytoplasm at about neutral pH it breaks down to release gaseous ethylene which
is commercially used for fruit ripening These hormones have a potential area of use in a wide
variety of fruits such as grapes cherries and citrus Promotion of female flower production in
cucurbits -cucumber squash and melon so as to increase the number of fruits produced per
plant It is also used for the promotion of flower initiation and controlled ripening in pineapples
Page 11 of 15
Economic Importance of Plant Growth Regulators
Other hormones
1 Florigen These hormones are synthesized in the older leaves and then transferred
to the growing region where it initiates the floral and bud initiation It is mainly
responsible for flowering in plants It also called flowering hormones
2 Anthesins Its newly discovered hormones responsible for flower formation
which horticulturists use to induce the early flowering in some plants
3 Vernalin It is used to undergo and bring nervalisation in some plants
4 Morphactins They are synthetic growth regulators which have the various roles
and functions as natural growth regulators It has been effective in flowering
stimulation sequence of flowering position and number of flowers formation of
flowers inflorescence parthenocarpy etc
Page 12 of 15
Economic Importance of Plant Growth Regulators
Conclusion
The plant growth regulators either synthetic or natural have been found great and wide
applications in agriculture and horticulture These growth regulators which in minute quantity
can have adverse effects to promote and modify a physiological process in plants On the
evidences of their adverse effects in small quantity these growth regulators have been found
greater applications and economic importance for farmers and horticulturists
The growth regulators are used to increase the fruit sizes to induce early flowering and
increase the number of flowering to break the dormancy of some seeds to quicken the maturity
and improve the fruit quality to increase the sugar content in sugarcane to increase the yield and
oil contents to promote the flower initiation and control ripening some other fruits and many
more Beside their major roles there are many other minor roles as sequence of flowering
position and number of flowers formation of flowers parthenocarpy root and shoot initiation
etc
The knowledge of these growth regulators have been advantages and boon to many
agriculturists and horticulturists globally Similarly we too can take advantages of their roles and
applications so as to make livelihood living and earn money some amount out of it Besides the
availability of these hormones in our places we too can go for it with the loaned investment
which is highly economic
In nutshell I would say that the plant growth regulators either synthetic or natural have
wide applications and uses for economical purposes and livelihood as well For it has been
found too crucial and economical to take the advantage of knowledge of the roles and
applications of growth regulators Theses growth regulators have been used widely in many other
countries unlike ours due to lack of access to the facilities
Therefore I request everyone to take advantage of its roles and applications and work for
economic purpose and livelihood Let us make use of those growth regulators
Page 13 of 15
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
Introduction
According to Devlin and Witham (1986) ldquoplant growth regulators are organic
compounds other than nutrients that in small amounts promote inhibit or otherwise modify a
physiological process in plants Plant hormones or phytohormones are regulators produced by
plants in which a low concentration regulates plant physiological processesrdquo (p 354) The
growth regulators can either be natural or synthetic and are widely being used in the agricultural
production and even for economic importance
The plant growth regulators have various economic importances in agricultural field
Their importance has been boon and advantages for farmers and horticulturists They took
advantage to earn by the practical implication and implication of these hormones and growth
regulators The very assignment mainly comprises of economic importance of plant growth
regulators
The plant growth regulators primarily include auxin gibberellin cytokinin
ethylene and abscisic acid (ABA) Secondarily it also includes florigens anthesin
vernalin morphactins etc Each growth regulators have various role and functions
which contributes to economic of the farmers and horticulturists worldwide
This assignment basically contains economic importance of each growth
regulator with different uses and practical application in agriculture and horticulture
For example auxins are used to increase fruit-sets control flowering etc Gibberellins
is used to increase sugar content in sugarcane etc Similarly every hormone posses different role
and economic importance where this very assignment mainly discusses as below
Page 2 of 15
Economic Importance of Plant Growth Regulators
Plant growth regulators Plant hormones Phytohormones
Plant hormones and growth regulators are chemicals that affect flowering aging root
growth distortion and killing of leaves stems and other parts prevention or promotion of stem
elongation etc
Rastogi (2011) defined that the plant growth regulator or phytohormone as an organic
substance produced naturally in plants controlling growth and other functions at a site remote
from its place of production in minute quantities Philips as cited in Pandey and Sinha (2006)
defined growth hormones as substances which are synthesized and transferred to other cells
where in extremely small quantities influence the developmental processes The growth
regulators can either be growth promoters or inhibitors A plant growth regulator is also an
organic compound either natural or synthetic that modifies or controls one or more specific
physiological processes within a plant through translocation And they can be either synthetic or
natural The growth regulators include
1 Auxins
2 Gibberellins
3 Cytokinins
4 Ethylene
5 Abscisic acid
6 Flowering hormones
7 Florigen Anthesins Vernalin Morphactinsetc
But major plant growth regulators are first five ones and are discussed as follows
1 Auxins
It is the plant growth regulators that mainly help in rooting besides its minor functions
This growth substance was found out by Charles Darwin in his book called The Power of
Movement of Plants He demonstrated that apical tips of seedlings are sensitive to unilateral
illumination and positive phototropism He concluded that the tip senses the unilateral light
stimulus but the curvature occurs down as a result of more rapid growth on the shaded than
illuminated side of the coleoptiles And he also noted that when the tip of coleoptiles was excised
Page 3 of 15
Economic Importance of Plant Growth Regulators
no curvature response occurred Therefore he said that when seedlings are freely exposed to
lateral light some influence is transmitted from the upper to lower part causing the later bent
Similar observations were made by Boysen-Jensen (1913) and Went (1928) They too did
and demonstrated on coleoptiles
Characteristics
1 Polar translocation- movement from apex to downward
2 Apical bud dominance
3 Variable behavior root and shoot growth
4 Root initiation
5 Belay in abscission
There are many different natural and synthetic auxins with different functions
1 Indole acetic acid-IAA
2 Indolebutyrib acid=IBA
3 Napthalene acetic acid-NAA
4 24-dichlorophenoxy acetic acid-24-D
Role of Auxin
The following are some of the responses that auxin is known to cause as cited by Davies 1995
Mauseth 1991 Raven 1992 Salisbury and Ross 1992
Stimulates cell elongation
Stimulates cell division in the cambium and in combination with cytokinins in tissue
culture
Stimulates differentiation of phloem and xylem
Stimulates root initiation on stem cuttings and lateral root development in tissue culture
Mediates the tropistic response of bending in response to gravity and light
The auxin supply from the apical bud suppresses growth of lateral buds
Page 4 of 15
Economic Importance of Plant Growth Regulators
Can induce fruit setting and growth in some plants
Delays fruit ripening
Promotes flowering
Stimulates growth of flower parts
Promotes femaleness in dioecious flowers
Stimulates the production of ethylene at high concentrations
Practical Application and its economic importance
1 Germination IAA IBA NPA 2 4-D are widely used to soak seeds for
germinationAuxins are widely used to break the dormancy of the seeds The pre-
treatment of seeds before sowing with IAA IBA 2 4-D etc found to have increased the
length of the hypocotyls at low concentration and shortening at higher concentration
Bhardwaj and Rao as cited in Pandey and Sinha (2006) reported that the effect of 24-D
on the growth and maturity of wheat and recorded 33 increased at 10 ppm treatment
Auxins can have very effective effects at very low concentration The higher concentration
and prolonged treatment retard and reduce germination
2 Rooting NAA and IBA are used for inducing the rooting of cuttings of woody plants
Malik and Chhonker as cited in Pandey and Sinha (2006) studied that the rooting effects
of different auxins and found out that the treatment of IBA and IAA are more superiors as
compared to other auxin type The effect of auxin NAA on mango varieties too has the
importance as a 10 induces 100 rooting
3 Flowering Hitchcock and Zimnermann as cited in Pandey and Sinha (2006) showed that
the even a minute quantity of auxins accelerated the flowering It is also reported that
IAA promotes the formation female flowers The application of auxins also helps to
increase the yield and flowering of wheat Das and Singh (1958) also studied the effect of
auxin IAA on flowering and fruiting in pineapple NAA and 2 4-D to induce flowering
in litchi and pineapple
4 ParthenocarpyIt is produced mainly by NAA and IBA Treatment of NAA in cucumber
and melon fruits produce seedless fruits (Das 1962)
Page 5 of 15
Economic Importance of Plant Growth Regulators
5 Weeds controlThey are selective weeds killers and considerably used in the destruction
of weds in crop fields rail-roads lawns and forests Common weedicides of auxin in
nature includes 2 4-D and 2 4 5-T etc
In Agriculture and Horticulture
Auxins are used for
1 Propagation of plants by hormone treatment in cuttings scions
2 Prevention of pre-harvest drop of fruits
3 Increasing parthenocarpy
4 Increasing fruit-sets
5 Inhibition of prolonged dormancy
6 Control of flowering
7 Defoliation of plants
8 Prevention of leaf falls or abscission
9 Selective weed killers
2 Gibberellins
It is the second major plant hormones which is mainly functional for shoot proliferation
besides flowering and breaking of seed dormancy It was first known by a Japneses farmer
Konishi (1898) and working was found out by Kurosawa in 1926 He discovered as GA It was
first extracted from the ascomycetous fungus GibberellaFujikuroi the casual organisms of
ldquofoolish seedling of ricerdquo or commonly called bakanae of rice The infected plants were taller
seedless and pale in colour These symptoms were produced due the substances secreted by the
fungus
It is mainly of gibberrelinGA3 or A3
Characteristics
1 Prevention of genetic and physiological dwarfism
2 Breaking of dormancy
3 Induction of flowering long day plants
Page 6 of 15
Economic Importance of Plant Growth Regulators
4 Increase amylase activity and
5 Substitute for chilling effects
Role of gibberellins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulate stem elongation by stimulating cell division and elongation
Stimulates boltingflowering in response to long days
Breaks seed dormancy in some plants which require stratification or light to induce
germination
Stimulates enzyme production -amylase in germinating cereal grains for mobilization of
seed reserves
Induces maleness in dioecious flowers (sex expression)
Can cause parthenocarpic fruit development
Can delay senescence in leaves and citrus fruits
Practical Application and its economic importance
1 Germination It has been widely used for germination experiments GA is found to
increase the length of hypocotyls and cotyledonary leaf (Chakravarti 1958) GA also has
important role in seed germination of cereals
2 Rooting Various experiments have suggested that the gibberellins have effect on
rooting Kato (1958) reported that it not only root initiation is inhibited but also the
stimulation of rooting by the auxin is also counteracted
3 Flowering GA induces flowering in long day plants and in plants requiring inductive
cold period It also promotes the formation of male flowers as it plays important role in
development of male flower
4 Parthenocarpy Mukerje and Dutta as cited in Pandey and Sinha (2006) have found out
that GA induces the formation of parthenocarpic fruits in brinjal It can also be done in
guava to produce parthenocarpic fruits It is also used to induce the parthenocarpy in
pome fruits and use to increase the fruit size and bunch length in grapes as well
Page 7 of 15
Economic Importance of Plant Growth Regulators
5 Fruit Setting GA affects more positively on fruit setting Randhaw and Singh (1959)
observed an increase in fruit setting in seedless grapes an increased in fruit size fruit set
total yield and quality in sweet lime have also been due to the treatment of GA
GAs is used to increase the size of Thompson grapes berries It is used by some breweries to
increase the rate of malting by increasing the potential of starch digestion Gibberellins are also
use to increase sugar cane growth and sugar yields
It posses great uses in increasing stalk length and production breaking of dormancy
inducing uniform crop emergence producing staminate flowers loosening of fruit clusters
increasing the fruit size quickening of maturity improving fruit quality controlling cracking of
fruits reducing non-productive period promoting vegetative growth and flower size increasing
sugar content in sugar cane inducing flowering and so on
3 Cytokinins
Skoog (1964) noted that in general ldquothe term Cytokinin is universally used for substance
which promotes cell division and exerts other growth regulatory functions as kinetinrdquo It also
promotes cell division and influence cell differentiation and aging of leaves
Characteristics
1 Initiation of cell division
2 Delay of senescence
3 Use of tissue culture
4 Counteract apical dominance
5 Induces flowering short day plants
Page 8 of 15
Economic Importance of Plant Growth Regulators
Role of Cytokinins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulates cell division
Stimulates morphogenesis -shoot initiationbud formation in tissue culture
Stimulates the growth of lateral buds-release of apical dominance
Stimulates leaf expansion resulting from cell enlargement
May enhance stomata opening in some species
Practical Application and its economic importance
1 Cell division Braun and Wood (1962) demonstrated that on exogenous supply of
cytokinin a normal Vinca cell converts to a turmour cell Skoog also showed that IAA
alone produces few mitoses in tobacco pith tissue but kinetinin combination with IAA
induces more mitoses This hormone never acts alone but in association or combination
with hormones like auxins cytokinins etc
2 Cell enlargement Scot and Liverman as cited in Pandey and Sinha (2006) reported the
property of cell enlargement in the disc of etiolated leaf by cytokinin Similar results
were also made in tobacco pith and cortical cells of tobacco roots
3 Dormancy It ahs been found quite effective in breaking the dormancy of the seeds and
other plant organ
4 Apical dominance Wickson and Thimann (1958) found that this hormone counteract
the usual apical dominace of bud These hormones have also been reported to induce the
lateral bud formation which is apparently related to the vascular tissue differentiation
The major use for cytokinins derives from its ability to delay senescence and maintain
greenness The artificial highly active cytokinin benzyladenine is the main compound used
The treatment of holly for festive decorations enables its harvest many weeks prior to use Post-
harvest sprays are now available to prolong the storage life of green vegetables such as
asparagus broccoli and celery
Page 9 of 15
Economic Importance of Plant Growth Regulators
These hormones also have used to increase shelf life of fruits quickening of root induction
and production of efficient root system It is also used to increase the yield and oil contents in
ground nuts to break the dormancy delay senescence causes cell division and so on
4 Abscissic Acid( ABA)
It is regarded as one of the principal accelerators of abscission and also bud dormancy It is
natural growth inhibitors and acts as a stress hormone that helps to cope with adverse
environmental conditions
Role of Abscissic Acid
A list of some of the known physiological effects caused by cytokinins is listed below
(Davies 1995 Mauseth 1991 Raven 1992 Salisbury and Ross 1992)
Stimulates the closure of stomata-water stress brings about an increase in ABA synthesis
Inhibits shoot growth but will not have as much affect on roots or may even promote
growth of roots
Induces seeds to synthesize storage proteins
Inhibits the affect of gibberellins on stimulating
Has some effect on induction and maintenance of dormancy
Induces gene transcription especially for proteinase inhibitors in response to wounding
which may explain an apparent role in pathogen defense
5 Ethylene
The only ripening hormone Denny as cited in Pandey and Sinha (2006) reported that
ethylene is highly effective in fruits ripening It is actually the natural product of ripening fruits
It is a gas at temperature under which a plant can survive It is a powerful inhibitor of root and
stem elongation
Page 10 of 15
Economic Importance of Plant Growth Regulators
Role of Ehtylene
Ethylene is known to affect the following plant processes (Davies 1995 Mauseth 1991
Raven 1992 Salisbury and Ross 1992)
Stimulates the release of dormancy
Stimulates shoot and root growth and differentiation (triple response)
May have a role in adventitious root formation
Stimulates leaf and fruit abscission
Stimulates Bromiliad flower induction
Induction of femaleness in dioecious flowers
Stimulates flower opening
Stimulates flower and leaf senescence
Stimulates fruit ripening
Practical Application and its economic importance
Ethylene gas a wide variety of uses but its gaseous nature precludes its applications in
non-enclosed spaces Ethylene itself can be used to enhance the ripening of fruits such as
bananas in storage following their shipment in an unripe condition An ethylene-producing liquid
chemical 2-chloroethylphosphonic acid - commercially called Ethrel or Ethephon has been
introduced and it is sprayed onto the plant at a slightly acid pH When it enters the cells and
encounters the cytoplasm at about neutral pH it breaks down to release gaseous ethylene which
is commercially used for fruit ripening These hormones have a potential area of use in a wide
variety of fruits such as grapes cherries and citrus Promotion of female flower production in
cucurbits -cucumber squash and melon so as to increase the number of fruits produced per
plant It is also used for the promotion of flower initiation and controlled ripening in pineapples
Page 11 of 15
Economic Importance of Plant Growth Regulators
Other hormones
1 Florigen These hormones are synthesized in the older leaves and then transferred
to the growing region where it initiates the floral and bud initiation It is mainly
responsible for flowering in plants It also called flowering hormones
2 Anthesins Its newly discovered hormones responsible for flower formation
which horticulturists use to induce the early flowering in some plants
3 Vernalin It is used to undergo and bring nervalisation in some plants
4 Morphactins They are synthetic growth regulators which have the various roles
and functions as natural growth regulators It has been effective in flowering
stimulation sequence of flowering position and number of flowers formation of
flowers inflorescence parthenocarpy etc
Page 12 of 15
Economic Importance of Plant Growth Regulators
Conclusion
The plant growth regulators either synthetic or natural have been found great and wide
applications in agriculture and horticulture These growth regulators which in minute quantity
can have adverse effects to promote and modify a physiological process in plants On the
evidences of their adverse effects in small quantity these growth regulators have been found
greater applications and economic importance for farmers and horticulturists
The growth regulators are used to increase the fruit sizes to induce early flowering and
increase the number of flowering to break the dormancy of some seeds to quicken the maturity
and improve the fruit quality to increase the sugar content in sugarcane to increase the yield and
oil contents to promote the flower initiation and control ripening some other fruits and many
more Beside their major roles there are many other minor roles as sequence of flowering
position and number of flowers formation of flowers parthenocarpy root and shoot initiation
etc
The knowledge of these growth regulators have been advantages and boon to many
agriculturists and horticulturists globally Similarly we too can take advantages of their roles and
applications so as to make livelihood living and earn money some amount out of it Besides the
availability of these hormones in our places we too can go for it with the loaned investment
which is highly economic
In nutshell I would say that the plant growth regulators either synthetic or natural have
wide applications and uses for economical purposes and livelihood as well For it has been
found too crucial and economical to take the advantage of knowledge of the roles and
applications of growth regulators Theses growth regulators have been used widely in many other
countries unlike ours due to lack of access to the facilities
Therefore I request everyone to take advantage of its roles and applications and work for
economic purpose and livelihood Let us make use of those growth regulators
Page 13 of 15
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
Plant growth regulators Plant hormones Phytohormones
Plant hormones and growth regulators are chemicals that affect flowering aging root
growth distortion and killing of leaves stems and other parts prevention or promotion of stem
elongation etc
Rastogi (2011) defined that the plant growth regulator or phytohormone as an organic
substance produced naturally in plants controlling growth and other functions at a site remote
from its place of production in minute quantities Philips as cited in Pandey and Sinha (2006)
defined growth hormones as substances which are synthesized and transferred to other cells
where in extremely small quantities influence the developmental processes The growth
regulators can either be growth promoters or inhibitors A plant growth regulator is also an
organic compound either natural or synthetic that modifies or controls one or more specific
physiological processes within a plant through translocation And they can be either synthetic or
natural The growth regulators include
1 Auxins
2 Gibberellins
3 Cytokinins
4 Ethylene
5 Abscisic acid
6 Flowering hormones
7 Florigen Anthesins Vernalin Morphactinsetc
But major plant growth regulators are first five ones and are discussed as follows
1 Auxins
It is the plant growth regulators that mainly help in rooting besides its minor functions
This growth substance was found out by Charles Darwin in his book called The Power of
Movement of Plants He demonstrated that apical tips of seedlings are sensitive to unilateral
illumination and positive phototropism He concluded that the tip senses the unilateral light
stimulus but the curvature occurs down as a result of more rapid growth on the shaded than
illuminated side of the coleoptiles And he also noted that when the tip of coleoptiles was excised
Page 3 of 15
Economic Importance of Plant Growth Regulators
no curvature response occurred Therefore he said that when seedlings are freely exposed to
lateral light some influence is transmitted from the upper to lower part causing the later bent
Similar observations were made by Boysen-Jensen (1913) and Went (1928) They too did
and demonstrated on coleoptiles
Characteristics
1 Polar translocation- movement from apex to downward
2 Apical bud dominance
3 Variable behavior root and shoot growth
4 Root initiation
5 Belay in abscission
There are many different natural and synthetic auxins with different functions
1 Indole acetic acid-IAA
2 Indolebutyrib acid=IBA
3 Napthalene acetic acid-NAA
4 24-dichlorophenoxy acetic acid-24-D
Role of Auxin
The following are some of the responses that auxin is known to cause as cited by Davies 1995
Mauseth 1991 Raven 1992 Salisbury and Ross 1992
Stimulates cell elongation
Stimulates cell division in the cambium and in combination with cytokinins in tissue
culture
Stimulates differentiation of phloem and xylem
Stimulates root initiation on stem cuttings and lateral root development in tissue culture
Mediates the tropistic response of bending in response to gravity and light
The auxin supply from the apical bud suppresses growth of lateral buds
Page 4 of 15
Economic Importance of Plant Growth Regulators
Can induce fruit setting and growth in some plants
Delays fruit ripening
Promotes flowering
Stimulates growth of flower parts
Promotes femaleness in dioecious flowers
Stimulates the production of ethylene at high concentrations
Practical Application and its economic importance
1 Germination IAA IBA NPA 2 4-D are widely used to soak seeds for
germinationAuxins are widely used to break the dormancy of the seeds The pre-
treatment of seeds before sowing with IAA IBA 2 4-D etc found to have increased the
length of the hypocotyls at low concentration and shortening at higher concentration
Bhardwaj and Rao as cited in Pandey and Sinha (2006) reported that the effect of 24-D
on the growth and maturity of wheat and recorded 33 increased at 10 ppm treatment
Auxins can have very effective effects at very low concentration The higher concentration
and prolonged treatment retard and reduce germination
2 Rooting NAA and IBA are used for inducing the rooting of cuttings of woody plants
Malik and Chhonker as cited in Pandey and Sinha (2006) studied that the rooting effects
of different auxins and found out that the treatment of IBA and IAA are more superiors as
compared to other auxin type The effect of auxin NAA on mango varieties too has the
importance as a 10 induces 100 rooting
3 Flowering Hitchcock and Zimnermann as cited in Pandey and Sinha (2006) showed that
the even a minute quantity of auxins accelerated the flowering It is also reported that
IAA promotes the formation female flowers The application of auxins also helps to
increase the yield and flowering of wheat Das and Singh (1958) also studied the effect of
auxin IAA on flowering and fruiting in pineapple NAA and 2 4-D to induce flowering
in litchi and pineapple
4 ParthenocarpyIt is produced mainly by NAA and IBA Treatment of NAA in cucumber
and melon fruits produce seedless fruits (Das 1962)
Page 5 of 15
Economic Importance of Plant Growth Regulators
5 Weeds controlThey are selective weeds killers and considerably used in the destruction
of weds in crop fields rail-roads lawns and forests Common weedicides of auxin in
nature includes 2 4-D and 2 4 5-T etc
In Agriculture and Horticulture
Auxins are used for
1 Propagation of plants by hormone treatment in cuttings scions
2 Prevention of pre-harvest drop of fruits
3 Increasing parthenocarpy
4 Increasing fruit-sets
5 Inhibition of prolonged dormancy
6 Control of flowering
7 Defoliation of plants
8 Prevention of leaf falls or abscission
9 Selective weed killers
2 Gibberellins
It is the second major plant hormones which is mainly functional for shoot proliferation
besides flowering and breaking of seed dormancy It was first known by a Japneses farmer
Konishi (1898) and working was found out by Kurosawa in 1926 He discovered as GA It was
first extracted from the ascomycetous fungus GibberellaFujikuroi the casual organisms of
ldquofoolish seedling of ricerdquo or commonly called bakanae of rice The infected plants were taller
seedless and pale in colour These symptoms were produced due the substances secreted by the
fungus
It is mainly of gibberrelinGA3 or A3
Characteristics
1 Prevention of genetic and physiological dwarfism
2 Breaking of dormancy
3 Induction of flowering long day plants
Page 6 of 15
Economic Importance of Plant Growth Regulators
4 Increase amylase activity and
5 Substitute for chilling effects
Role of gibberellins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulate stem elongation by stimulating cell division and elongation
Stimulates boltingflowering in response to long days
Breaks seed dormancy in some plants which require stratification or light to induce
germination
Stimulates enzyme production -amylase in germinating cereal grains for mobilization of
seed reserves
Induces maleness in dioecious flowers (sex expression)
Can cause parthenocarpic fruit development
Can delay senescence in leaves and citrus fruits
Practical Application and its economic importance
1 Germination It has been widely used for germination experiments GA is found to
increase the length of hypocotyls and cotyledonary leaf (Chakravarti 1958) GA also has
important role in seed germination of cereals
2 Rooting Various experiments have suggested that the gibberellins have effect on
rooting Kato (1958) reported that it not only root initiation is inhibited but also the
stimulation of rooting by the auxin is also counteracted
3 Flowering GA induces flowering in long day plants and in plants requiring inductive
cold period It also promotes the formation of male flowers as it plays important role in
development of male flower
4 Parthenocarpy Mukerje and Dutta as cited in Pandey and Sinha (2006) have found out
that GA induces the formation of parthenocarpic fruits in brinjal It can also be done in
guava to produce parthenocarpic fruits It is also used to induce the parthenocarpy in
pome fruits and use to increase the fruit size and bunch length in grapes as well
Page 7 of 15
Economic Importance of Plant Growth Regulators
5 Fruit Setting GA affects more positively on fruit setting Randhaw and Singh (1959)
observed an increase in fruit setting in seedless grapes an increased in fruit size fruit set
total yield and quality in sweet lime have also been due to the treatment of GA
GAs is used to increase the size of Thompson grapes berries It is used by some breweries to
increase the rate of malting by increasing the potential of starch digestion Gibberellins are also
use to increase sugar cane growth and sugar yields
It posses great uses in increasing stalk length and production breaking of dormancy
inducing uniform crop emergence producing staminate flowers loosening of fruit clusters
increasing the fruit size quickening of maturity improving fruit quality controlling cracking of
fruits reducing non-productive period promoting vegetative growth and flower size increasing
sugar content in sugar cane inducing flowering and so on
3 Cytokinins
Skoog (1964) noted that in general ldquothe term Cytokinin is universally used for substance
which promotes cell division and exerts other growth regulatory functions as kinetinrdquo It also
promotes cell division and influence cell differentiation and aging of leaves
Characteristics
1 Initiation of cell division
2 Delay of senescence
3 Use of tissue culture
4 Counteract apical dominance
5 Induces flowering short day plants
Page 8 of 15
Economic Importance of Plant Growth Regulators
Role of Cytokinins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulates cell division
Stimulates morphogenesis -shoot initiationbud formation in tissue culture
Stimulates the growth of lateral buds-release of apical dominance
Stimulates leaf expansion resulting from cell enlargement
May enhance stomata opening in some species
Practical Application and its economic importance
1 Cell division Braun and Wood (1962) demonstrated that on exogenous supply of
cytokinin a normal Vinca cell converts to a turmour cell Skoog also showed that IAA
alone produces few mitoses in tobacco pith tissue but kinetinin combination with IAA
induces more mitoses This hormone never acts alone but in association or combination
with hormones like auxins cytokinins etc
2 Cell enlargement Scot and Liverman as cited in Pandey and Sinha (2006) reported the
property of cell enlargement in the disc of etiolated leaf by cytokinin Similar results
were also made in tobacco pith and cortical cells of tobacco roots
3 Dormancy It ahs been found quite effective in breaking the dormancy of the seeds and
other plant organ
4 Apical dominance Wickson and Thimann (1958) found that this hormone counteract
the usual apical dominace of bud These hormones have also been reported to induce the
lateral bud formation which is apparently related to the vascular tissue differentiation
The major use for cytokinins derives from its ability to delay senescence and maintain
greenness The artificial highly active cytokinin benzyladenine is the main compound used
The treatment of holly for festive decorations enables its harvest many weeks prior to use Post-
harvest sprays are now available to prolong the storage life of green vegetables such as
asparagus broccoli and celery
Page 9 of 15
Economic Importance of Plant Growth Regulators
These hormones also have used to increase shelf life of fruits quickening of root induction
and production of efficient root system It is also used to increase the yield and oil contents in
ground nuts to break the dormancy delay senescence causes cell division and so on
4 Abscissic Acid( ABA)
It is regarded as one of the principal accelerators of abscission and also bud dormancy It is
natural growth inhibitors and acts as a stress hormone that helps to cope with adverse
environmental conditions
Role of Abscissic Acid
A list of some of the known physiological effects caused by cytokinins is listed below
(Davies 1995 Mauseth 1991 Raven 1992 Salisbury and Ross 1992)
Stimulates the closure of stomata-water stress brings about an increase in ABA synthesis
Inhibits shoot growth but will not have as much affect on roots or may even promote
growth of roots
Induces seeds to synthesize storage proteins
Inhibits the affect of gibberellins on stimulating
Has some effect on induction and maintenance of dormancy
Induces gene transcription especially for proteinase inhibitors in response to wounding
which may explain an apparent role in pathogen defense
5 Ethylene
The only ripening hormone Denny as cited in Pandey and Sinha (2006) reported that
ethylene is highly effective in fruits ripening It is actually the natural product of ripening fruits
It is a gas at temperature under which a plant can survive It is a powerful inhibitor of root and
stem elongation
Page 10 of 15
Economic Importance of Plant Growth Regulators
Role of Ehtylene
Ethylene is known to affect the following plant processes (Davies 1995 Mauseth 1991
Raven 1992 Salisbury and Ross 1992)
Stimulates the release of dormancy
Stimulates shoot and root growth and differentiation (triple response)
May have a role in adventitious root formation
Stimulates leaf and fruit abscission
Stimulates Bromiliad flower induction
Induction of femaleness in dioecious flowers
Stimulates flower opening
Stimulates flower and leaf senescence
Stimulates fruit ripening
Practical Application and its economic importance
Ethylene gas a wide variety of uses but its gaseous nature precludes its applications in
non-enclosed spaces Ethylene itself can be used to enhance the ripening of fruits such as
bananas in storage following their shipment in an unripe condition An ethylene-producing liquid
chemical 2-chloroethylphosphonic acid - commercially called Ethrel or Ethephon has been
introduced and it is sprayed onto the plant at a slightly acid pH When it enters the cells and
encounters the cytoplasm at about neutral pH it breaks down to release gaseous ethylene which
is commercially used for fruit ripening These hormones have a potential area of use in a wide
variety of fruits such as grapes cherries and citrus Promotion of female flower production in
cucurbits -cucumber squash and melon so as to increase the number of fruits produced per
plant It is also used for the promotion of flower initiation and controlled ripening in pineapples
Page 11 of 15
Economic Importance of Plant Growth Regulators
Other hormones
1 Florigen These hormones are synthesized in the older leaves and then transferred
to the growing region where it initiates the floral and bud initiation It is mainly
responsible for flowering in plants It also called flowering hormones
2 Anthesins Its newly discovered hormones responsible for flower formation
which horticulturists use to induce the early flowering in some plants
3 Vernalin It is used to undergo and bring nervalisation in some plants
4 Morphactins They are synthetic growth regulators which have the various roles
and functions as natural growth regulators It has been effective in flowering
stimulation sequence of flowering position and number of flowers formation of
flowers inflorescence parthenocarpy etc
Page 12 of 15
Economic Importance of Plant Growth Regulators
Conclusion
The plant growth regulators either synthetic or natural have been found great and wide
applications in agriculture and horticulture These growth regulators which in minute quantity
can have adverse effects to promote and modify a physiological process in plants On the
evidences of their adverse effects in small quantity these growth regulators have been found
greater applications and economic importance for farmers and horticulturists
The growth regulators are used to increase the fruit sizes to induce early flowering and
increase the number of flowering to break the dormancy of some seeds to quicken the maturity
and improve the fruit quality to increase the sugar content in sugarcane to increase the yield and
oil contents to promote the flower initiation and control ripening some other fruits and many
more Beside their major roles there are many other minor roles as sequence of flowering
position and number of flowers formation of flowers parthenocarpy root and shoot initiation
etc
The knowledge of these growth regulators have been advantages and boon to many
agriculturists and horticulturists globally Similarly we too can take advantages of their roles and
applications so as to make livelihood living and earn money some amount out of it Besides the
availability of these hormones in our places we too can go for it with the loaned investment
which is highly economic
In nutshell I would say that the plant growth regulators either synthetic or natural have
wide applications and uses for economical purposes and livelihood as well For it has been
found too crucial and economical to take the advantage of knowledge of the roles and
applications of growth regulators Theses growth regulators have been used widely in many other
countries unlike ours due to lack of access to the facilities
Therefore I request everyone to take advantage of its roles and applications and work for
economic purpose and livelihood Let us make use of those growth regulators
Page 13 of 15
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
no curvature response occurred Therefore he said that when seedlings are freely exposed to
lateral light some influence is transmitted from the upper to lower part causing the later bent
Similar observations were made by Boysen-Jensen (1913) and Went (1928) They too did
and demonstrated on coleoptiles
Characteristics
1 Polar translocation- movement from apex to downward
2 Apical bud dominance
3 Variable behavior root and shoot growth
4 Root initiation
5 Belay in abscission
There are many different natural and synthetic auxins with different functions
1 Indole acetic acid-IAA
2 Indolebutyrib acid=IBA
3 Napthalene acetic acid-NAA
4 24-dichlorophenoxy acetic acid-24-D
Role of Auxin
The following are some of the responses that auxin is known to cause as cited by Davies 1995
Mauseth 1991 Raven 1992 Salisbury and Ross 1992
Stimulates cell elongation
Stimulates cell division in the cambium and in combination with cytokinins in tissue
culture
Stimulates differentiation of phloem and xylem
Stimulates root initiation on stem cuttings and lateral root development in tissue culture
Mediates the tropistic response of bending in response to gravity and light
The auxin supply from the apical bud suppresses growth of lateral buds
Page 4 of 15
Economic Importance of Plant Growth Regulators
Can induce fruit setting and growth in some plants
Delays fruit ripening
Promotes flowering
Stimulates growth of flower parts
Promotes femaleness in dioecious flowers
Stimulates the production of ethylene at high concentrations
Practical Application and its economic importance
1 Germination IAA IBA NPA 2 4-D are widely used to soak seeds for
germinationAuxins are widely used to break the dormancy of the seeds The pre-
treatment of seeds before sowing with IAA IBA 2 4-D etc found to have increased the
length of the hypocotyls at low concentration and shortening at higher concentration
Bhardwaj and Rao as cited in Pandey and Sinha (2006) reported that the effect of 24-D
on the growth and maturity of wheat and recorded 33 increased at 10 ppm treatment
Auxins can have very effective effects at very low concentration The higher concentration
and prolonged treatment retard and reduce germination
2 Rooting NAA and IBA are used for inducing the rooting of cuttings of woody plants
Malik and Chhonker as cited in Pandey and Sinha (2006) studied that the rooting effects
of different auxins and found out that the treatment of IBA and IAA are more superiors as
compared to other auxin type The effect of auxin NAA on mango varieties too has the
importance as a 10 induces 100 rooting
3 Flowering Hitchcock and Zimnermann as cited in Pandey and Sinha (2006) showed that
the even a minute quantity of auxins accelerated the flowering It is also reported that
IAA promotes the formation female flowers The application of auxins also helps to
increase the yield and flowering of wheat Das and Singh (1958) also studied the effect of
auxin IAA on flowering and fruiting in pineapple NAA and 2 4-D to induce flowering
in litchi and pineapple
4 ParthenocarpyIt is produced mainly by NAA and IBA Treatment of NAA in cucumber
and melon fruits produce seedless fruits (Das 1962)
Page 5 of 15
Economic Importance of Plant Growth Regulators
5 Weeds controlThey are selective weeds killers and considerably used in the destruction
of weds in crop fields rail-roads lawns and forests Common weedicides of auxin in
nature includes 2 4-D and 2 4 5-T etc
In Agriculture and Horticulture
Auxins are used for
1 Propagation of plants by hormone treatment in cuttings scions
2 Prevention of pre-harvest drop of fruits
3 Increasing parthenocarpy
4 Increasing fruit-sets
5 Inhibition of prolonged dormancy
6 Control of flowering
7 Defoliation of plants
8 Prevention of leaf falls or abscission
9 Selective weed killers
2 Gibberellins
It is the second major plant hormones which is mainly functional for shoot proliferation
besides flowering and breaking of seed dormancy It was first known by a Japneses farmer
Konishi (1898) and working was found out by Kurosawa in 1926 He discovered as GA It was
first extracted from the ascomycetous fungus GibberellaFujikuroi the casual organisms of
ldquofoolish seedling of ricerdquo or commonly called bakanae of rice The infected plants were taller
seedless and pale in colour These symptoms were produced due the substances secreted by the
fungus
It is mainly of gibberrelinGA3 or A3
Characteristics
1 Prevention of genetic and physiological dwarfism
2 Breaking of dormancy
3 Induction of flowering long day plants
Page 6 of 15
Economic Importance of Plant Growth Regulators
4 Increase amylase activity and
5 Substitute for chilling effects
Role of gibberellins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulate stem elongation by stimulating cell division and elongation
Stimulates boltingflowering in response to long days
Breaks seed dormancy in some plants which require stratification or light to induce
germination
Stimulates enzyme production -amylase in germinating cereal grains for mobilization of
seed reserves
Induces maleness in dioecious flowers (sex expression)
Can cause parthenocarpic fruit development
Can delay senescence in leaves and citrus fruits
Practical Application and its economic importance
1 Germination It has been widely used for germination experiments GA is found to
increase the length of hypocotyls and cotyledonary leaf (Chakravarti 1958) GA also has
important role in seed germination of cereals
2 Rooting Various experiments have suggested that the gibberellins have effect on
rooting Kato (1958) reported that it not only root initiation is inhibited but also the
stimulation of rooting by the auxin is also counteracted
3 Flowering GA induces flowering in long day plants and in plants requiring inductive
cold period It also promotes the formation of male flowers as it plays important role in
development of male flower
4 Parthenocarpy Mukerje and Dutta as cited in Pandey and Sinha (2006) have found out
that GA induces the formation of parthenocarpic fruits in brinjal It can also be done in
guava to produce parthenocarpic fruits It is also used to induce the parthenocarpy in
pome fruits and use to increase the fruit size and bunch length in grapes as well
Page 7 of 15
Economic Importance of Plant Growth Regulators
5 Fruit Setting GA affects more positively on fruit setting Randhaw and Singh (1959)
observed an increase in fruit setting in seedless grapes an increased in fruit size fruit set
total yield and quality in sweet lime have also been due to the treatment of GA
GAs is used to increase the size of Thompson grapes berries It is used by some breweries to
increase the rate of malting by increasing the potential of starch digestion Gibberellins are also
use to increase sugar cane growth and sugar yields
It posses great uses in increasing stalk length and production breaking of dormancy
inducing uniform crop emergence producing staminate flowers loosening of fruit clusters
increasing the fruit size quickening of maturity improving fruit quality controlling cracking of
fruits reducing non-productive period promoting vegetative growth and flower size increasing
sugar content in sugar cane inducing flowering and so on
3 Cytokinins
Skoog (1964) noted that in general ldquothe term Cytokinin is universally used for substance
which promotes cell division and exerts other growth regulatory functions as kinetinrdquo It also
promotes cell division and influence cell differentiation and aging of leaves
Characteristics
1 Initiation of cell division
2 Delay of senescence
3 Use of tissue culture
4 Counteract apical dominance
5 Induces flowering short day plants
Page 8 of 15
Economic Importance of Plant Growth Regulators
Role of Cytokinins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulates cell division
Stimulates morphogenesis -shoot initiationbud formation in tissue culture
Stimulates the growth of lateral buds-release of apical dominance
Stimulates leaf expansion resulting from cell enlargement
May enhance stomata opening in some species
Practical Application and its economic importance
1 Cell division Braun and Wood (1962) demonstrated that on exogenous supply of
cytokinin a normal Vinca cell converts to a turmour cell Skoog also showed that IAA
alone produces few mitoses in tobacco pith tissue but kinetinin combination with IAA
induces more mitoses This hormone never acts alone but in association or combination
with hormones like auxins cytokinins etc
2 Cell enlargement Scot and Liverman as cited in Pandey and Sinha (2006) reported the
property of cell enlargement in the disc of etiolated leaf by cytokinin Similar results
were also made in tobacco pith and cortical cells of tobacco roots
3 Dormancy It ahs been found quite effective in breaking the dormancy of the seeds and
other plant organ
4 Apical dominance Wickson and Thimann (1958) found that this hormone counteract
the usual apical dominace of bud These hormones have also been reported to induce the
lateral bud formation which is apparently related to the vascular tissue differentiation
The major use for cytokinins derives from its ability to delay senescence and maintain
greenness The artificial highly active cytokinin benzyladenine is the main compound used
The treatment of holly for festive decorations enables its harvest many weeks prior to use Post-
harvest sprays are now available to prolong the storage life of green vegetables such as
asparagus broccoli and celery
Page 9 of 15
Economic Importance of Plant Growth Regulators
These hormones also have used to increase shelf life of fruits quickening of root induction
and production of efficient root system It is also used to increase the yield and oil contents in
ground nuts to break the dormancy delay senescence causes cell division and so on
4 Abscissic Acid( ABA)
It is regarded as one of the principal accelerators of abscission and also bud dormancy It is
natural growth inhibitors and acts as a stress hormone that helps to cope with adverse
environmental conditions
Role of Abscissic Acid
A list of some of the known physiological effects caused by cytokinins is listed below
(Davies 1995 Mauseth 1991 Raven 1992 Salisbury and Ross 1992)
Stimulates the closure of stomata-water stress brings about an increase in ABA synthesis
Inhibits shoot growth but will not have as much affect on roots or may even promote
growth of roots
Induces seeds to synthesize storage proteins
Inhibits the affect of gibberellins on stimulating
Has some effect on induction and maintenance of dormancy
Induces gene transcription especially for proteinase inhibitors in response to wounding
which may explain an apparent role in pathogen defense
5 Ethylene
The only ripening hormone Denny as cited in Pandey and Sinha (2006) reported that
ethylene is highly effective in fruits ripening It is actually the natural product of ripening fruits
It is a gas at temperature under which a plant can survive It is a powerful inhibitor of root and
stem elongation
Page 10 of 15
Economic Importance of Plant Growth Regulators
Role of Ehtylene
Ethylene is known to affect the following plant processes (Davies 1995 Mauseth 1991
Raven 1992 Salisbury and Ross 1992)
Stimulates the release of dormancy
Stimulates shoot and root growth and differentiation (triple response)
May have a role in adventitious root formation
Stimulates leaf and fruit abscission
Stimulates Bromiliad flower induction
Induction of femaleness in dioecious flowers
Stimulates flower opening
Stimulates flower and leaf senescence
Stimulates fruit ripening
Practical Application and its economic importance
Ethylene gas a wide variety of uses but its gaseous nature precludes its applications in
non-enclosed spaces Ethylene itself can be used to enhance the ripening of fruits such as
bananas in storage following their shipment in an unripe condition An ethylene-producing liquid
chemical 2-chloroethylphosphonic acid - commercially called Ethrel or Ethephon has been
introduced and it is sprayed onto the plant at a slightly acid pH When it enters the cells and
encounters the cytoplasm at about neutral pH it breaks down to release gaseous ethylene which
is commercially used for fruit ripening These hormones have a potential area of use in a wide
variety of fruits such as grapes cherries and citrus Promotion of female flower production in
cucurbits -cucumber squash and melon so as to increase the number of fruits produced per
plant It is also used for the promotion of flower initiation and controlled ripening in pineapples
Page 11 of 15
Economic Importance of Plant Growth Regulators
Other hormones
1 Florigen These hormones are synthesized in the older leaves and then transferred
to the growing region where it initiates the floral and bud initiation It is mainly
responsible for flowering in plants It also called flowering hormones
2 Anthesins Its newly discovered hormones responsible for flower formation
which horticulturists use to induce the early flowering in some plants
3 Vernalin It is used to undergo and bring nervalisation in some plants
4 Morphactins They are synthetic growth regulators which have the various roles
and functions as natural growth regulators It has been effective in flowering
stimulation sequence of flowering position and number of flowers formation of
flowers inflorescence parthenocarpy etc
Page 12 of 15
Economic Importance of Plant Growth Regulators
Conclusion
The plant growth regulators either synthetic or natural have been found great and wide
applications in agriculture and horticulture These growth regulators which in minute quantity
can have adverse effects to promote and modify a physiological process in plants On the
evidences of their adverse effects in small quantity these growth regulators have been found
greater applications and economic importance for farmers and horticulturists
The growth regulators are used to increase the fruit sizes to induce early flowering and
increase the number of flowering to break the dormancy of some seeds to quicken the maturity
and improve the fruit quality to increase the sugar content in sugarcane to increase the yield and
oil contents to promote the flower initiation and control ripening some other fruits and many
more Beside their major roles there are many other minor roles as sequence of flowering
position and number of flowers formation of flowers parthenocarpy root and shoot initiation
etc
The knowledge of these growth regulators have been advantages and boon to many
agriculturists and horticulturists globally Similarly we too can take advantages of their roles and
applications so as to make livelihood living and earn money some amount out of it Besides the
availability of these hormones in our places we too can go for it with the loaned investment
which is highly economic
In nutshell I would say that the plant growth regulators either synthetic or natural have
wide applications and uses for economical purposes and livelihood as well For it has been
found too crucial and economical to take the advantage of knowledge of the roles and
applications of growth regulators Theses growth regulators have been used widely in many other
countries unlike ours due to lack of access to the facilities
Therefore I request everyone to take advantage of its roles and applications and work for
economic purpose and livelihood Let us make use of those growth regulators
Page 13 of 15
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
Can induce fruit setting and growth in some plants
Delays fruit ripening
Promotes flowering
Stimulates growth of flower parts
Promotes femaleness in dioecious flowers
Stimulates the production of ethylene at high concentrations
Practical Application and its economic importance
1 Germination IAA IBA NPA 2 4-D are widely used to soak seeds for
germinationAuxins are widely used to break the dormancy of the seeds The pre-
treatment of seeds before sowing with IAA IBA 2 4-D etc found to have increased the
length of the hypocotyls at low concentration and shortening at higher concentration
Bhardwaj and Rao as cited in Pandey and Sinha (2006) reported that the effect of 24-D
on the growth and maturity of wheat and recorded 33 increased at 10 ppm treatment
Auxins can have very effective effects at very low concentration The higher concentration
and prolonged treatment retard and reduce germination
2 Rooting NAA and IBA are used for inducing the rooting of cuttings of woody plants
Malik and Chhonker as cited in Pandey and Sinha (2006) studied that the rooting effects
of different auxins and found out that the treatment of IBA and IAA are more superiors as
compared to other auxin type The effect of auxin NAA on mango varieties too has the
importance as a 10 induces 100 rooting
3 Flowering Hitchcock and Zimnermann as cited in Pandey and Sinha (2006) showed that
the even a minute quantity of auxins accelerated the flowering It is also reported that
IAA promotes the formation female flowers The application of auxins also helps to
increase the yield and flowering of wheat Das and Singh (1958) also studied the effect of
auxin IAA on flowering and fruiting in pineapple NAA and 2 4-D to induce flowering
in litchi and pineapple
4 ParthenocarpyIt is produced mainly by NAA and IBA Treatment of NAA in cucumber
and melon fruits produce seedless fruits (Das 1962)
Page 5 of 15
Economic Importance of Plant Growth Regulators
5 Weeds controlThey are selective weeds killers and considerably used in the destruction
of weds in crop fields rail-roads lawns and forests Common weedicides of auxin in
nature includes 2 4-D and 2 4 5-T etc
In Agriculture and Horticulture
Auxins are used for
1 Propagation of plants by hormone treatment in cuttings scions
2 Prevention of pre-harvest drop of fruits
3 Increasing parthenocarpy
4 Increasing fruit-sets
5 Inhibition of prolonged dormancy
6 Control of flowering
7 Defoliation of plants
8 Prevention of leaf falls or abscission
9 Selective weed killers
2 Gibberellins
It is the second major plant hormones which is mainly functional for shoot proliferation
besides flowering and breaking of seed dormancy It was first known by a Japneses farmer
Konishi (1898) and working was found out by Kurosawa in 1926 He discovered as GA It was
first extracted from the ascomycetous fungus GibberellaFujikuroi the casual organisms of
ldquofoolish seedling of ricerdquo or commonly called bakanae of rice The infected plants were taller
seedless and pale in colour These symptoms were produced due the substances secreted by the
fungus
It is mainly of gibberrelinGA3 or A3
Characteristics
1 Prevention of genetic and physiological dwarfism
2 Breaking of dormancy
3 Induction of flowering long day plants
Page 6 of 15
Economic Importance of Plant Growth Regulators
4 Increase amylase activity and
5 Substitute for chilling effects
Role of gibberellins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulate stem elongation by stimulating cell division and elongation
Stimulates boltingflowering in response to long days
Breaks seed dormancy in some plants which require stratification or light to induce
germination
Stimulates enzyme production -amylase in germinating cereal grains for mobilization of
seed reserves
Induces maleness in dioecious flowers (sex expression)
Can cause parthenocarpic fruit development
Can delay senescence in leaves and citrus fruits
Practical Application and its economic importance
1 Germination It has been widely used for germination experiments GA is found to
increase the length of hypocotyls and cotyledonary leaf (Chakravarti 1958) GA also has
important role in seed germination of cereals
2 Rooting Various experiments have suggested that the gibberellins have effect on
rooting Kato (1958) reported that it not only root initiation is inhibited but also the
stimulation of rooting by the auxin is also counteracted
3 Flowering GA induces flowering in long day plants and in plants requiring inductive
cold period It also promotes the formation of male flowers as it plays important role in
development of male flower
4 Parthenocarpy Mukerje and Dutta as cited in Pandey and Sinha (2006) have found out
that GA induces the formation of parthenocarpic fruits in brinjal It can also be done in
guava to produce parthenocarpic fruits It is also used to induce the parthenocarpy in
pome fruits and use to increase the fruit size and bunch length in grapes as well
Page 7 of 15
Economic Importance of Plant Growth Regulators
5 Fruit Setting GA affects more positively on fruit setting Randhaw and Singh (1959)
observed an increase in fruit setting in seedless grapes an increased in fruit size fruit set
total yield and quality in sweet lime have also been due to the treatment of GA
GAs is used to increase the size of Thompson grapes berries It is used by some breweries to
increase the rate of malting by increasing the potential of starch digestion Gibberellins are also
use to increase sugar cane growth and sugar yields
It posses great uses in increasing stalk length and production breaking of dormancy
inducing uniform crop emergence producing staminate flowers loosening of fruit clusters
increasing the fruit size quickening of maturity improving fruit quality controlling cracking of
fruits reducing non-productive period promoting vegetative growth and flower size increasing
sugar content in sugar cane inducing flowering and so on
3 Cytokinins
Skoog (1964) noted that in general ldquothe term Cytokinin is universally used for substance
which promotes cell division and exerts other growth regulatory functions as kinetinrdquo It also
promotes cell division and influence cell differentiation and aging of leaves
Characteristics
1 Initiation of cell division
2 Delay of senescence
3 Use of tissue culture
4 Counteract apical dominance
5 Induces flowering short day plants
Page 8 of 15
Economic Importance of Plant Growth Regulators
Role of Cytokinins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulates cell division
Stimulates morphogenesis -shoot initiationbud formation in tissue culture
Stimulates the growth of lateral buds-release of apical dominance
Stimulates leaf expansion resulting from cell enlargement
May enhance stomata opening in some species
Practical Application and its economic importance
1 Cell division Braun and Wood (1962) demonstrated that on exogenous supply of
cytokinin a normal Vinca cell converts to a turmour cell Skoog also showed that IAA
alone produces few mitoses in tobacco pith tissue but kinetinin combination with IAA
induces more mitoses This hormone never acts alone but in association or combination
with hormones like auxins cytokinins etc
2 Cell enlargement Scot and Liverman as cited in Pandey and Sinha (2006) reported the
property of cell enlargement in the disc of etiolated leaf by cytokinin Similar results
were also made in tobacco pith and cortical cells of tobacco roots
3 Dormancy It ahs been found quite effective in breaking the dormancy of the seeds and
other plant organ
4 Apical dominance Wickson and Thimann (1958) found that this hormone counteract
the usual apical dominace of bud These hormones have also been reported to induce the
lateral bud formation which is apparently related to the vascular tissue differentiation
The major use for cytokinins derives from its ability to delay senescence and maintain
greenness The artificial highly active cytokinin benzyladenine is the main compound used
The treatment of holly for festive decorations enables its harvest many weeks prior to use Post-
harvest sprays are now available to prolong the storage life of green vegetables such as
asparagus broccoli and celery
Page 9 of 15
Economic Importance of Plant Growth Regulators
These hormones also have used to increase shelf life of fruits quickening of root induction
and production of efficient root system It is also used to increase the yield and oil contents in
ground nuts to break the dormancy delay senescence causes cell division and so on
4 Abscissic Acid( ABA)
It is regarded as one of the principal accelerators of abscission and also bud dormancy It is
natural growth inhibitors and acts as a stress hormone that helps to cope with adverse
environmental conditions
Role of Abscissic Acid
A list of some of the known physiological effects caused by cytokinins is listed below
(Davies 1995 Mauseth 1991 Raven 1992 Salisbury and Ross 1992)
Stimulates the closure of stomata-water stress brings about an increase in ABA synthesis
Inhibits shoot growth but will not have as much affect on roots or may even promote
growth of roots
Induces seeds to synthesize storage proteins
Inhibits the affect of gibberellins on stimulating
Has some effect on induction and maintenance of dormancy
Induces gene transcription especially for proteinase inhibitors in response to wounding
which may explain an apparent role in pathogen defense
5 Ethylene
The only ripening hormone Denny as cited in Pandey and Sinha (2006) reported that
ethylene is highly effective in fruits ripening It is actually the natural product of ripening fruits
It is a gas at temperature under which a plant can survive It is a powerful inhibitor of root and
stem elongation
Page 10 of 15
Economic Importance of Plant Growth Regulators
Role of Ehtylene
Ethylene is known to affect the following plant processes (Davies 1995 Mauseth 1991
Raven 1992 Salisbury and Ross 1992)
Stimulates the release of dormancy
Stimulates shoot and root growth and differentiation (triple response)
May have a role in adventitious root formation
Stimulates leaf and fruit abscission
Stimulates Bromiliad flower induction
Induction of femaleness in dioecious flowers
Stimulates flower opening
Stimulates flower and leaf senescence
Stimulates fruit ripening
Practical Application and its economic importance
Ethylene gas a wide variety of uses but its gaseous nature precludes its applications in
non-enclosed spaces Ethylene itself can be used to enhance the ripening of fruits such as
bananas in storage following their shipment in an unripe condition An ethylene-producing liquid
chemical 2-chloroethylphosphonic acid - commercially called Ethrel or Ethephon has been
introduced and it is sprayed onto the plant at a slightly acid pH When it enters the cells and
encounters the cytoplasm at about neutral pH it breaks down to release gaseous ethylene which
is commercially used for fruit ripening These hormones have a potential area of use in a wide
variety of fruits such as grapes cherries and citrus Promotion of female flower production in
cucurbits -cucumber squash and melon so as to increase the number of fruits produced per
plant It is also used for the promotion of flower initiation and controlled ripening in pineapples
Page 11 of 15
Economic Importance of Plant Growth Regulators
Other hormones
1 Florigen These hormones are synthesized in the older leaves and then transferred
to the growing region where it initiates the floral and bud initiation It is mainly
responsible for flowering in plants It also called flowering hormones
2 Anthesins Its newly discovered hormones responsible for flower formation
which horticulturists use to induce the early flowering in some plants
3 Vernalin It is used to undergo and bring nervalisation in some plants
4 Morphactins They are synthetic growth regulators which have the various roles
and functions as natural growth regulators It has been effective in flowering
stimulation sequence of flowering position and number of flowers formation of
flowers inflorescence parthenocarpy etc
Page 12 of 15
Economic Importance of Plant Growth Regulators
Conclusion
The plant growth regulators either synthetic or natural have been found great and wide
applications in agriculture and horticulture These growth regulators which in minute quantity
can have adverse effects to promote and modify a physiological process in plants On the
evidences of their adverse effects in small quantity these growth regulators have been found
greater applications and economic importance for farmers and horticulturists
The growth regulators are used to increase the fruit sizes to induce early flowering and
increase the number of flowering to break the dormancy of some seeds to quicken the maturity
and improve the fruit quality to increase the sugar content in sugarcane to increase the yield and
oil contents to promote the flower initiation and control ripening some other fruits and many
more Beside their major roles there are many other minor roles as sequence of flowering
position and number of flowers formation of flowers parthenocarpy root and shoot initiation
etc
The knowledge of these growth regulators have been advantages and boon to many
agriculturists and horticulturists globally Similarly we too can take advantages of their roles and
applications so as to make livelihood living and earn money some amount out of it Besides the
availability of these hormones in our places we too can go for it with the loaned investment
which is highly economic
In nutshell I would say that the plant growth regulators either synthetic or natural have
wide applications and uses for economical purposes and livelihood as well For it has been
found too crucial and economical to take the advantage of knowledge of the roles and
applications of growth regulators Theses growth regulators have been used widely in many other
countries unlike ours due to lack of access to the facilities
Therefore I request everyone to take advantage of its roles and applications and work for
economic purpose and livelihood Let us make use of those growth regulators
Page 13 of 15
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
5 Weeds controlThey are selective weeds killers and considerably used in the destruction
of weds in crop fields rail-roads lawns and forests Common weedicides of auxin in
nature includes 2 4-D and 2 4 5-T etc
In Agriculture and Horticulture
Auxins are used for
1 Propagation of plants by hormone treatment in cuttings scions
2 Prevention of pre-harvest drop of fruits
3 Increasing parthenocarpy
4 Increasing fruit-sets
5 Inhibition of prolonged dormancy
6 Control of flowering
7 Defoliation of plants
8 Prevention of leaf falls or abscission
9 Selective weed killers
2 Gibberellins
It is the second major plant hormones which is mainly functional for shoot proliferation
besides flowering and breaking of seed dormancy It was first known by a Japneses farmer
Konishi (1898) and working was found out by Kurosawa in 1926 He discovered as GA It was
first extracted from the ascomycetous fungus GibberellaFujikuroi the casual organisms of
ldquofoolish seedling of ricerdquo or commonly called bakanae of rice The infected plants were taller
seedless and pale in colour These symptoms were produced due the substances secreted by the
fungus
It is mainly of gibberrelinGA3 or A3
Characteristics
1 Prevention of genetic and physiological dwarfism
2 Breaking of dormancy
3 Induction of flowering long day plants
Page 6 of 15
Economic Importance of Plant Growth Regulators
4 Increase amylase activity and
5 Substitute for chilling effects
Role of gibberellins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulate stem elongation by stimulating cell division and elongation
Stimulates boltingflowering in response to long days
Breaks seed dormancy in some plants which require stratification or light to induce
germination
Stimulates enzyme production -amylase in germinating cereal grains for mobilization of
seed reserves
Induces maleness in dioecious flowers (sex expression)
Can cause parthenocarpic fruit development
Can delay senescence in leaves and citrus fruits
Practical Application and its economic importance
1 Germination It has been widely used for germination experiments GA is found to
increase the length of hypocotyls and cotyledonary leaf (Chakravarti 1958) GA also has
important role in seed germination of cereals
2 Rooting Various experiments have suggested that the gibberellins have effect on
rooting Kato (1958) reported that it not only root initiation is inhibited but also the
stimulation of rooting by the auxin is also counteracted
3 Flowering GA induces flowering in long day plants and in plants requiring inductive
cold period It also promotes the formation of male flowers as it plays important role in
development of male flower
4 Parthenocarpy Mukerje and Dutta as cited in Pandey and Sinha (2006) have found out
that GA induces the formation of parthenocarpic fruits in brinjal It can also be done in
guava to produce parthenocarpic fruits It is also used to induce the parthenocarpy in
pome fruits and use to increase the fruit size and bunch length in grapes as well
Page 7 of 15
Economic Importance of Plant Growth Regulators
5 Fruit Setting GA affects more positively on fruit setting Randhaw and Singh (1959)
observed an increase in fruit setting in seedless grapes an increased in fruit size fruit set
total yield and quality in sweet lime have also been due to the treatment of GA
GAs is used to increase the size of Thompson grapes berries It is used by some breweries to
increase the rate of malting by increasing the potential of starch digestion Gibberellins are also
use to increase sugar cane growth and sugar yields
It posses great uses in increasing stalk length and production breaking of dormancy
inducing uniform crop emergence producing staminate flowers loosening of fruit clusters
increasing the fruit size quickening of maturity improving fruit quality controlling cracking of
fruits reducing non-productive period promoting vegetative growth and flower size increasing
sugar content in sugar cane inducing flowering and so on
3 Cytokinins
Skoog (1964) noted that in general ldquothe term Cytokinin is universally used for substance
which promotes cell division and exerts other growth regulatory functions as kinetinrdquo It also
promotes cell division and influence cell differentiation and aging of leaves
Characteristics
1 Initiation of cell division
2 Delay of senescence
3 Use of tissue culture
4 Counteract apical dominance
5 Induces flowering short day plants
Page 8 of 15
Economic Importance of Plant Growth Regulators
Role of Cytokinins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulates cell division
Stimulates morphogenesis -shoot initiationbud formation in tissue culture
Stimulates the growth of lateral buds-release of apical dominance
Stimulates leaf expansion resulting from cell enlargement
May enhance stomata opening in some species
Practical Application and its economic importance
1 Cell division Braun and Wood (1962) demonstrated that on exogenous supply of
cytokinin a normal Vinca cell converts to a turmour cell Skoog also showed that IAA
alone produces few mitoses in tobacco pith tissue but kinetinin combination with IAA
induces more mitoses This hormone never acts alone but in association or combination
with hormones like auxins cytokinins etc
2 Cell enlargement Scot and Liverman as cited in Pandey and Sinha (2006) reported the
property of cell enlargement in the disc of etiolated leaf by cytokinin Similar results
were also made in tobacco pith and cortical cells of tobacco roots
3 Dormancy It ahs been found quite effective in breaking the dormancy of the seeds and
other plant organ
4 Apical dominance Wickson and Thimann (1958) found that this hormone counteract
the usual apical dominace of bud These hormones have also been reported to induce the
lateral bud formation which is apparently related to the vascular tissue differentiation
The major use for cytokinins derives from its ability to delay senescence and maintain
greenness The artificial highly active cytokinin benzyladenine is the main compound used
The treatment of holly for festive decorations enables its harvest many weeks prior to use Post-
harvest sprays are now available to prolong the storage life of green vegetables such as
asparagus broccoli and celery
Page 9 of 15
Economic Importance of Plant Growth Regulators
These hormones also have used to increase shelf life of fruits quickening of root induction
and production of efficient root system It is also used to increase the yield and oil contents in
ground nuts to break the dormancy delay senescence causes cell division and so on
4 Abscissic Acid( ABA)
It is regarded as one of the principal accelerators of abscission and also bud dormancy It is
natural growth inhibitors and acts as a stress hormone that helps to cope with adverse
environmental conditions
Role of Abscissic Acid
A list of some of the known physiological effects caused by cytokinins is listed below
(Davies 1995 Mauseth 1991 Raven 1992 Salisbury and Ross 1992)
Stimulates the closure of stomata-water stress brings about an increase in ABA synthesis
Inhibits shoot growth but will not have as much affect on roots or may even promote
growth of roots
Induces seeds to synthesize storage proteins
Inhibits the affect of gibberellins on stimulating
Has some effect on induction and maintenance of dormancy
Induces gene transcription especially for proteinase inhibitors in response to wounding
which may explain an apparent role in pathogen defense
5 Ethylene
The only ripening hormone Denny as cited in Pandey and Sinha (2006) reported that
ethylene is highly effective in fruits ripening It is actually the natural product of ripening fruits
It is a gas at temperature under which a plant can survive It is a powerful inhibitor of root and
stem elongation
Page 10 of 15
Economic Importance of Plant Growth Regulators
Role of Ehtylene
Ethylene is known to affect the following plant processes (Davies 1995 Mauseth 1991
Raven 1992 Salisbury and Ross 1992)
Stimulates the release of dormancy
Stimulates shoot and root growth and differentiation (triple response)
May have a role in adventitious root formation
Stimulates leaf and fruit abscission
Stimulates Bromiliad flower induction
Induction of femaleness in dioecious flowers
Stimulates flower opening
Stimulates flower and leaf senescence
Stimulates fruit ripening
Practical Application and its economic importance
Ethylene gas a wide variety of uses but its gaseous nature precludes its applications in
non-enclosed spaces Ethylene itself can be used to enhance the ripening of fruits such as
bananas in storage following their shipment in an unripe condition An ethylene-producing liquid
chemical 2-chloroethylphosphonic acid - commercially called Ethrel or Ethephon has been
introduced and it is sprayed onto the plant at a slightly acid pH When it enters the cells and
encounters the cytoplasm at about neutral pH it breaks down to release gaseous ethylene which
is commercially used for fruit ripening These hormones have a potential area of use in a wide
variety of fruits such as grapes cherries and citrus Promotion of female flower production in
cucurbits -cucumber squash and melon so as to increase the number of fruits produced per
plant It is also used for the promotion of flower initiation and controlled ripening in pineapples
Page 11 of 15
Economic Importance of Plant Growth Regulators
Other hormones
1 Florigen These hormones are synthesized in the older leaves and then transferred
to the growing region where it initiates the floral and bud initiation It is mainly
responsible for flowering in plants It also called flowering hormones
2 Anthesins Its newly discovered hormones responsible for flower formation
which horticulturists use to induce the early flowering in some plants
3 Vernalin It is used to undergo and bring nervalisation in some plants
4 Morphactins They are synthetic growth regulators which have the various roles
and functions as natural growth regulators It has been effective in flowering
stimulation sequence of flowering position and number of flowers formation of
flowers inflorescence parthenocarpy etc
Page 12 of 15
Economic Importance of Plant Growth Regulators
Conclusion
The plant growth regulators either synthetic or natural have been found great and wide
applications in agriculture and horticulture These growth regulators which in minute quantity
can have adverse effects to promote and modify a physiological process in plants On the
evidences of their adverse effects in small quantity these growth regulators have been found
greater applications and economic importance for farmers and horticulturists
The growth regulators are used to increase the fruit sizes to induce early flowering and
increase the number of flowering to break the dormancy of some seeds to quicken the maturity
and improve the fruit quality to increase the sugar content in sugarcane to increase the yield and
oil contents to promote the flower initiation and control ripening some other fruits and many
more Beside their major roles there are many other minor roles as sequence of flowering
position and number of flowers formation of flowers parthenocarpy root and shoot initiation
etc
The knowledge of these growth regulators have been advantages and boon to many
agriculturists and horticulturists globally Similarly we too can take advantages of their roles and
applications so as to make livelihood living and earn money some amount out of it Besides the
availability of these hormones in our places we too can go for it with the loaned investment
which is highly economic
In nutshell I would say that the plant growth regulators either synthetic or natural have
wide applications and uses for economical purposes and livelihood as well For it has been
found too crucial and economical to take the advantage of knowledge of the roles and
applications of growth regulators Theses growth regulators have been used widely in many other
countries unlike ours due to lack of access to the facilities
Therefore I request everyone to take advantage of its roles and applications and work for
economic purpose and livelihood Let us make use of those growth regulators
Page 13 of 15
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
4 Increase amylase activity and
5 Substitute for chilling effects
Role of gibberellins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulate stem elongation by stimulating cell division and elongation
Stimulates boltingflowering in response to long days
Breaks seed dormancy in some plants which require stratification or light to induce
germination
Stimulates enzyme production -amylase in germinating cereal grains for mobilization of
seed reserves
Induces maleness in dioecious flowers (sex expression)
Can cause parthenocarpic fruit development
Can delay senescence in leaves and citrus fruits
Practical Application and its economic importance
1 Germination It has been widely used for germination experiments GA is found to
increase the length of hypocotyls and cotyledonary leaf (Chakravarti 1958) GA also has
important role in seed germination of cereals
2 Rooting Various experiments have suggested that the gibberellins have effect on
rooting Kato (1958) reported that it not only root initiation is inhibited but also the
stimulation of rooting by the auxin is also counteracted
3 Flowering GA induces flowering in long day plants and in plants requiring inductive
cold period It also promotes the formation of male flowers as it plays important role in
development of male flower
4 Parthenocarpy Mukerje and Dutta as cited in Pandey and Sinha (2006) have found out
that GA induces the formation of parthenocarpic fruits in brinjal It can also be done in
guava to produce parthenocarpic fruits It is also used to induce the parthenocarpy in
pome fruits and use to increase the fruit size and bunch length in grapes as well
Page 7 of 15
Economic Importance of Plant Growth Regulators
5 Fruit Setting GA affects more positively on fruit setting Randhaw and Singh (1959)
observed an increase in fruit setting in seedless grapes an increased in fruit size fruit set
total yield and quality in sweet lime have also been due to the treatment of GA
GAs is used to increase the size of Thompson grapes berries It is used by some breweries to
increase the rate of malting by increasing the potential of starch digestion Gibberellins are also
use to increase sugar cane growth and sugar yields
It posses great uses in increasing stalk length and production breaking of dormancy
inducing uniform crop emergence producing staminate flowers loosening of fruit clusters
increasing the fruit size quickening of maturity improving fruit quality controlling cracking of
fruits reducing non-productive period promoting vegetative growth and flower size increasing
sugar content in sugar cane inducing flowering and so on
3 Cytokinins
Skoog (1964) noted that in general ldquothe term Cytokinin is universally used for substance
which promotes cell division and exerts other growth regulatory functions as kinetinrdquo It also
promotes cell division and influence cell differentiation and aging of leaves
Characteristics
1 Initiation of cell division
2 Delay of senescence
3 Use of tissue culture
4 Counteract apical dominance
5 Induces flowering short day plants
Page 8 of 15
Economic Importance of Plant Growth Regulators
Role of Cytokinins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulates cell division
Stimulates morphogenesis -shoot initiationbud formation in tissue culture
Stimulates the growth of lateral buds-release of apical dominance
Stimulates leaf expansion resulting from cell enlargement
May enhance stomata opening in some species
Practical Application and its economic importance
1 Cell division Braun and Wood (1962) demonstrated that on exogenous supply of
cytokinin a normal Vinca cell converts to a turmour cell Skoog also showed that IAA
alone produces few mitoses in tobacco pith tissue but kinetinin combination with IAA
induces more mitoses This hormone never acts alone but in association or combination
with hormones like auxins cytokinins etc
2 Cell enlargement Scot and Liverman as cited in Pandey and Sinha (2006) reported the
property of cell enlargement in the disc of etiolated leaf by cytokinin Similar results
were also made in tobacco pith and cortical cells of tobacco roots
3 Dormancy It ahs been found quite effective in breaking the dormancy of the seeds and
other plant organ
4 Apical dominance Wickson and Thimann (1958) found that this hormone counteract
the usual apical dominace of bud These hormones have also been reported to induce the
lateral bud formation which is apparently related to the vascular tissue differentiation
The major use for cytokinins derives from its ability to delay senescence and maintain
greenness The artificial highly active cytokinin benzyladenine is the main compound used
The treatment of holly for festive decorations enables its harvest many weeks prior to use Post-
harvest sprays are now available to prolong the storage life of green vegetables such as
asparagus broccoli and celery
Page 9 of 15
Economic Importance of Plant Growth Regulators
These hormones also have used to increase shelf life of fruits quickening of root induction
and production of efficient root system It is also used to increase the yield and oil contents in
ground nuts to break the dormancy delay senescence causes cell division and so on
4 Abscissic Acid( ABA)
It is regarded as one of the principal accelerators of abscission and also bud dormancy It is
natural growth inhibitors and acts as a stress hormone that helps to cope with adverse
environmental conditions
Role of Abscissic Acid
A list of some of the known physiological effects caused by cytokinins is listed below
(Davies 1995 Mauseth 1991 Raven 1992 Salisbury and Ross 1992)
Stimulates the closure of stomata-water stress brings about an increase in ABA synthesis
Inhibits shoot growth but will not have as much affect on roots or may even promote
growth of roots
Induces seeds to synthesize storage proteins
Inhibits the affect of gibberellins on stimulating
Has some effect on induction and maintenance of dormancy
Induces gene transcription especially for proteinase inhibitors in response to wounding
which may explain an apparent role in pathogen defense
5 Ethylene
The only ripening hormone Denny as cited in Pandey and Sinha (2006) reported that
ethylene is highly effective in fruits ripening It is actually the natural product of ripening fruits
It is a gas at temperature under which a plant can survive It is a powerful inhibitor of root and
stem elongation
Page 10 of 15
Economic Importance of Plant Growth Regulators
Role of Ehtylene
Ethylene is known to affect the following plant processes (Davies 1995 Mauseth 1991
Raven 1992 Salisbury and Ross 1992)
Stimulates the release of dormancy
Stimulates shoot and root growth and differentiation (triple response)
May have a role in adventitious root formation
Stimulates leaf and fruit abscission
Stimulates Bromiliad flower induction
Induction of femaleness in dioecious flowers
Stimulates flower opening
Stimulates flower and leaf senescence
Stimulates fruit ripening
Practical Application and its economic importance
Ethylene gas a wide variety of uses but its gaseous nature precludes its applications in
non-enclosed spaces Ethylene itself can be used to enhance the ripening of fruits such as
bananas in storage following their shipment in an unripe condition An ethylene-producing liquid
chemical 2-chloroethylphosphonic acid - commercially called Ethrel or Ethephon has been
introduced and it is sprayed onto the plant at a slightly acid pH When it enters the cells and
encounters the cytoplasm at about neutral pH it breaks down to release gaseous ethylene which
is commercially used for fruit ripening These hormones have a potential area of use in a wide
variety of fruits such as grapes cherries and citrus Promotion of female flower production in
cucurbits -cucumber squash and melon so as to increase the number of fruits produced per
plant It is also used for the promotion of flower initiation and controlled ripening in pineapples
Page 11 of 15
Economic Importance of Plant Growth Regulators
Other hormones
1 Florigen These hormones are synthesized in the older leaves and then transferred
to the growing region where it initiates the floral and bud initiation It is mainly
responsible for flowering in plants It also called flowering hormones
2 Anthesins Its newly discovered hormones responsible for flower formation
which horticulturists use to induce the early flowering in some plants
3 Vernalin It is used to undergo and bring nervalisation in some plants
4 Morphactins They are synthetic growth regulators which have the various roles
and functions as natural growth regulators It has been effective in flowering
stimulation sequence of flowering position and number of flowers formation of
flowers inflorescence parthenocarpy etc
Page 12 of 15
Economic Importance of Plant Growth Regulators
Conclusion
The plant growth regulators either synthetic or natural have been found great and wide
applications in agriculture and horticulture These growth regulators which in minute quantity
can have adverse effects to promote and modify a physiological process in plants On the
evidences of their adverse effects in small quantity these growth regulators have been found
greater applications and economic importance for farmers and horticulturists
The growth regulators are used to increase the fruit sizes to induce early flowering and
increase the number of flowering to break the dormancy of some seeds to quicken the maturity
and improve the fruit quality to increase the sugar content in sugarcane to increase the yield and
oil contents to promote the flower initiation and control ripening some other fruits and many
more Beside their major roles there are many other minor roles as sequence of flowering
position and number of flowers formation of flowers parthenocarpy root and shoot initiation
etc
The knowledge of these growth regulators have been advantages and boon to many
agriculturists and horticulturists globally Similarly we too can take advantages of their roles and
applications so as to make livelihood living and earn money some amount out of it Besides the
availability of these hormones in our places we too can go for it with the loaned investment
which is highly economic
In nutshell I would say that the plant growth regulators either synthetic or natural have
wide applications and uses for economical purposes and livelihood as well For it has been
found too crucial and economical to take the advantage of knowledge of the roles and
applications of growth regulators Theses growth regulators have been used widely in many other
countries unlike ours due to lack of access to the facilities
Therefore I request everyone to take advantage of its roles and applications and work for
economic purpose and livelihood Let us make use of those growth regulators
Page 13 of 15
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
5 Fruit Setting GA affects more positively on fruit setting Randhaw and Singh (1959)
observed an increase in fruit setting in seedless grapes an increased in fruit size fruit set
total yield and quality in sweet lime have also been due to the treatment of GA
GAs is used to increase the size of Thompson grapes berries It is used by some breweries to
increase the rate of malting by increasing the potential of starch digestion Gibberellins are also
use to increase sugar cane growth and sugar yields
It posses great uses in increasing stalk length and production breaking of dormancy
inducing uniform crop emergence producing staminate flowers loosening of fruit clusters
increasing the fruit size quickening of maturity improving fruit quality controlling cracking of
fruits reducing non-productive period promoting vegetative growth and flower size increasing
sugar content in sugar cane inducing flowering and so on
3 Cytokinins
Skoog (1964) noted that in general ldquothe term Cytokinin is universally used for substance
which promotes cell division and exerts other growth regulatory functions as kinetinrdquo It also
promotes cell division and influence cell differentiation and aging of leaves
Characteristics
1 Initiation of cell division
2 Delay of senescence
3 Use of tissue culture
4 Counteract apical dominance
5 Induces flowering short day plants
Page 8 of 15
Economic Importance of Plant Growth Regulators
Role of Cytokinins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulates cell division
Stimulates morphogenesis -shoot initiationbud formation in tissue culture
Stimulates the growth of lateral buds-release of apical dominance
Stimulates leaf expansion resulting from cell enlargement
May enhance stomata opening in some species
Practical Application and its economic importance
1 Cell division Braun and Wood (1962) demonstrated that on exogenous supply of
cytokinin a normal Vinca cell converts to a turmour cell Skoog also showed that IAA
alone produces few mitoses in tobacco pith tissue but kinetinin combination with IAA
induces more mitoses This hormone never acts alone but in association or combination
with hormones like auxins cytokinins etc
2 Cell enlargement Scot and Liverman as cited in Pandey and Sinha (2006) reported the
property of cell enlargement in the disc of etiolated leaf by cytokinin Similar results
were also made in tobacco pith and cortical cells of tobacco roots
3 Dormancy It ahs been found quite effective in breaking the dormancy of the seeds and
other plant organ
4 Apical dominance Wickson and Thimann (1958) found that this hormone counteract
the usual apical dominace of bud These hormones have also been reported to induce the
lateral bud formation which is apparently related to the vascular tissue differentiation
The major use for cytokinins derives from its ability to delay senescence and maintain
greenness The artificial highly active cytokinin benzyladenine is the main compound used
The treatment of holly for festive decorations enables its harvest many weeks prior to use Post-
harvest sprays are now available to prolong the storage life of green vegetables such as
asparagus broccoli and celery
Page 9 of 15
Economic Importance of Plant Growth Regulators
These hormones also have used to increase shelf life of fruits quickening of root induction
and production of efficient root system It is also used to increase the yield and oil contents in
ground nuts to break the dormancy delay senescence causes cell division and so on
4 Abscissic Acid( ABA)
It is regarded as one of the principal accelerators of abscission and also bud dormancy It is
natural growth inhibitors and acts as a stress hormone that helps to cope with adverse
environmental conditions
Role of Abscissic Acid
A list of some of the known physiological effects caused by cytokinins is listed below
(Davies 1995 Mauseth 1991 Raven 1992 Salisbury and Ross 1992)
Stimulates the closure of stomata-water stress brings about an increase in ABA synthesis
Inhibits shoot growth but will not have as much affect on roots or may even promote
growth of roots
Induces seeds to synthesize storage proteins
Inhibits the affect of gibberellins on stimulating
Has some effect on induction and maintenance of dormancy
Induces gene transcription especially for proteinase inhibitors in response to wounding
which may explain an apparent role in pathogen defense
5 Ethylene
The only ripening hormone Denny as cited in Pandey and Sinha (2006) reported that
ethylene is highly effective in fruits ripening It is actually the natural product of ripening fruits
It is a gas at temperature under which a plant can survive It is a powerful inhibitor of root and
stem elongation
Page 10 of 15
Economic Importance of Plant Growth Regulators
Role of Ehtylene
Ethylene is known to affect the following plant processes (Davies 1995 Mauseth 1991
Raven 1992 Salisbury and Ross 1992)
Stimulates the release of dormancy
Stimulates shoot and root growth and differentiation (triple response)
May have a role in adventitious root formation
Stimulates leaf and fruit abscission
Stimulates Bromiliad flower induction
Induction of femaleness in dioecious flowers
Stimulates flower opening
Stimulates flower and leaf senescence
Stimulates fruit ripening
Practical Application and its economic importance
Ethylene gas a wide variety of uses but its gaseous nature precludes its applications in
non-enclosed spaces Ethylene itself can be used to enhance the ripening of fruits such as
bananas in storage following their shipment in an unripe condition An ethylene-producing liquid
chemical 2-chloroethylphosphonic acid - commercially called Ethrel or Ethephon has been
introduced and it is sprayed onto the plant at a slightly acid pH When it enters the cells and
encounters the cytoplasm at about neutral pH it breaks down to release gaseous ethylene which
is commercially used for fruit ripening These hormones have a potential area of use in a wide
variety of fruits such as grapes cherries and citrus Promotion of female flower production in
cucurbits -cucumber squash and melon so as to increase the number of fruits produced per
plant It is also used for the promotion of flower initiation and controlled ripening in pineapples
Page 11 of 15
Economic Importance of Plant Growth Regulators
Other hormones
1 Florigen These hormones are synthesized in the older leaves and then transferred
to the growing region where it initiates the floral and bud initiation It is mainly
responsible for flowering in plants It also called flowering hormones
2 Anthesins Its newly discovered hormones responsible for flower formation
which horticulturists use to induce the early flowering in some plants
3 Vernalin It is used to undergo and bring nervalisation in some plants
4 Morphactins They are synthetic growth regulators which have the various roles
and functions as natural growth regulators It has been effective in flowering
stimulation sequence of flowering position and number of flowers formation of
flowers inflorescence parthenocarpy etc
Page 12 of 15
Economic Importance of Plant Growth Regulators
Conclusion
The plant growth regulators either synthetic or natural have been found great and wide
applications in agriculture and horticulture These growth regulators which in minute quantity
can have adverse effects to promote and modify a physiological process in plants On the
evidences of their adverse effects in small quantity these growth regulators have been found
greater applications and economic importance for farmers and horticulturists
The growth regulators are used to increase the fruit sizes to induce early flowering and
increase the number of flowering to break the dormancy of some seeds to quicken the maturity
and improve the fruit quality to increase the sugar content in sugarcane to increase the yield and
oil contents to promote the flower initiation and control ripening some other fruits and many
more Beside their major roles there are many other minor roles as sequence of flowering
position and number of flowers formation of flowers parthenocarpy root and shoot initiation
etc
The knowledge of these growth regulators have been advantages and boon to many
agriculturists and horticulturists globally Similarly we too can take advantages of their roles and
applications so as to make livelihood living and earn money some amount out of it Besides the
availability of these hormones in our places we too can go for it with the loaned investment
which is highly economic
In nutshell I would say that the plant growth regulators either synthetic or natural have
wide applications and uses for economical purposes and livelihood as well For it has been
found too crucial and economical to take the advantage of knowledge of the roles and
applications of growth regulators Theses growth regulators have been used widely in many other
countries unlike ours due to lack of access to the facilities
Therefore I request everyone to take advantage of its roles and applications and work for
economic purpose and livelihood Let us make use of those growth regulators
Page 13 of 15
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
Role of Cytokinins
The following are the roles and functions of gibberellins as cited by Davies 1995 Mauseth
1991 Raven 1992 Salisbury and Ross 1992
Stimulates cell division
Stimulates morphogenesis -shoot initiationbud formation in tissue culture
Stimulates the growth of lateral buds-release of apical dominance
Stimulates leaf expansion resulting from cell enlargement
May enhance stomata opening in some species
Practical Application and its economic importance
1 Cell division Braun and Wood (1962) demonstrated that on exogenous supply of
cytokinin a normal Vinca cell converts to a turmour cell Skoog also showed that IAA
alone produces few mitoses in tobacco pith tissue but kinetinin combination with IAA
induces more mitoses This hormone never acts alone but in association or combination
with hormones like auxins cytokinins etc
2 Cell enlargement Scot and Liverman as cited in Pandey and Sinha (2006) reported the
property of cell enlargement in the disc of etiolated leaf by cytokinin Similar results
were also made in tobacco pith and cortical cells of tobacco roots
3 Dormancy It ahs been found quite effective in breaking the dormancy of the seeds and
other plant organ
4 Apical dominance Wickson and Thimann (1958) found that this hormone counteract
the usual apical dominace of bud These hormones have also been reported to induce the
lateral bud formation which is apparently related to the vascular tissue differentiation
The major use for cytokinins derives from its ability to delay senescence and maintain
greenness The artificial highly active cytokinin benzyladenine is the main compound used
The treatment of holly for festive decorations enables its harvest many weeks prior to use Post-
harvest sprays are now available to prolong the storage life of green vegetables such as
asparagus broccoli and celery
Page 9 of 15
Economic Importance of Plant Growth Regulators
These hormones also have used to increase shelf life of fruits quickening of root induction
and production of efficient root system It is also used to increase the yield and oil contents in
ground nuts to break the dormancy delay senescence causes cell division and so on
4 Abscissic Acid( ABA)
It is regarded as one of the principal accelerators of abscission and also bud dormancy It is
natural growth inhibitors and acts as a stress hormone that helps to cope with adverse
environmental conditions
Role of Abscissic Acid
A list of some of the known physiological effects caused by cytokinins is listed below
(Davies 1995 Mauseth 1991 Raven 1992 Salisbury and Ross 1992)
Stimulates the closure of stomata-water stress brings about an increase in ABA synthesis
Inhibits shoot growth but will not have as much affect on roots or may even promote
growth of roots
Induces seeds to synthesize storage proteins
Inhibits the affect of gibberellins on stimulating
Has some effect on induction and maintenance of dormancy
Induces gene transcription especially for proteinase inhibitors in response to wounding
which may explain an apparent role in pathogen defense
5 Ethylene
The only ripening hormone Denny as cited in Pandey and Sinha (2006) reported that
ethylene is highly effective in fruits ripening It is actually the natural product of ripening fruits
It is a gas at temperature under which a plant can survive It is a powerful inhibitor of root and
stem elongation
Page 10 of 15
Economic Importance of Plant Growth Regulators
Role of Ehtylene
Ethylene is known to affect the following plant processes (Davies 1995 Mauseth 1991
Raven 1992 Salisbury and Ross 1992)
Stimulates the release of dormancy
Stimulates shoot and root growth and differentiation (triple response)
May have a role in adventitious root formation
Stimulates leaf and fruit abscission
Stimulates Bromiliad flower induction
Induction of femaleness in dioecious flowers
Stimulates flower opening
Stimulates flower and leaf senescence
Stimulates fruit ripening
Practical Application and its economic importance
Ethylene gas a wide variety of uses but its gaseous nature precludes its applications in
non-enclosed spaces Ethylene itself can be used to enhance the ripening of fruits such as
bananas in storage following their shipment in an unripe condition An ethylene-producing liquid
chemical 2-chloroethylphosphonic acid - commercially called Ethrel or Ethephon has been
introduced and it is sprayed onto the plant at a slightly acid pH When it enters the cells and
encounters the cytoplasm at about neutral pH it breaks down to release gaseous ethylene which
is commercially used for fruit ripening These hormones have a potential area of use in a wide
variety of fruits such as grapes cherries and citrus Promotion of female flower production in
cucurbits -cucumber squash and melon so as to increase the number of fruits produced per
plant It is also used for the promotion of flower initiation and controlled ripening in pineapples
Page 11 of 15
Economic Importance of Plant Growth Regulators
Other hormones
1 Florigen These hormones are synthesized in the older leaves and then transferred
to the growing region where it initiates the floral and bud initiation It is mainly
responsible for flowering in plants It also called flowering hormones
2 Anthesins Its newly discovered hormones responsible for flower formation
which horticulturists use to induce the early flowering in some plants
3 Vernalin It is used to undergo and bring nervalisation in some plants
4 Morphactins They are synthetic growth regulators which have the various roles
and functions as natural growth regulators It has been effective in flowering
stimulation sequence of flowering position and number of flowers formation of
flowers inflorescence parthenocarpy etc
Page 12 of 15
Economic Importance of Plant Growth Regulators
Conclusion
The plant growth regulators either synthetic or natural have been found great and wide
applications in agriculture and horticulture These growth regulators which in minute quantity
can have adverse effects to promote and modify a physiological process in plants On the
evidences of their adverse effects in small quantity these growth regulators have been found
greater applications and economic importance for farmers and horticulturists
The growth regulators are used to increase the fruit sizes to induce early flowering and
increase the number of flowering to break the dormancy of some seeds to quicken the maturity
and improve the fruit quality to increase the sugar content in sugarcane to increase the yield and
oil contents to promote the flower initiation and control ripening some other fruits and many
more Beside their major roles there are many other minor roles as sequence of flowering
position and number of flowers formation of flowers parthenocarpy root and shoot initiation
etc
The knowledge of these growth regulators have been advantages and boon to many
agriculturists and horticulturists globally Similarly we too can take advantages of their roles and
applications so as to make livelihood living and earn money some amount out of it Besides the
availability of these hormones in our places we too can go for it with the loaned investment
which is highly economic
In nutshell I would say that the plant growth regulators either synthetic or natural have
wide applications and uses for economical purposes and livelihood as well For it has been
found too crucial and economical to take the advantage of knowledge of the roles and
applications of growth regulators Theses growth regulators have been used widely in many other
countries unlike ours due to lack of access to the facilities
Therefore I request everyone to take advantage of its roles and applications and work for
economic purpose and livelihood Let us make use of those growth regulators
Page 13 of 15
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
These hormones also have used to increase shelf life of fruits quickening of root induction
and production of efficient root system It is also used to increase the yield and oil contents in
ground nuts to break the dormancy delay senescence causes cell division and so on
4 Abscissic Acid( ABA)
It is regarded as one of the principal accelerators of abscission and also bud dormancy It is
natural growth inhibitors and acts as a stress hormone that helps to cope with adverse
environmental conditions
Role of Abscissic Acid
A list of some of the known physiological effects caused by cytokinins is listed below
(Davies 1995 Mauseth 1991 Raven 1992 Salisbury and Ross 1992)
Stimulates the closure of stomata-water stress brings about an increase in ABA synthesis
Inhibits shoot growth but will not have as much affect on roots or may even promote
growth of roots
Induces seeds to synthesize storage proteins
Inhibits the affect of gibberellins on stimulating
Has some effect on induction and maintenance of dormancy
Induces gene transcription especially for proteinase inhibitors in response to wounding
which may explain an apparent role in pathogen defense
5 Ethylene
The only ripening hormone Denny as cited in Pandey and Sinha (2006) reported that
ethylene is highly effective in fruits ripening It is actually the natural product of ripening fruits
It is a gas at temperature under which a plant can survive It is a powerful inhibitor of root and
stem elongation
Page 10 of 15
Economic Importance of Plant Growth Regulators
Role of Ehtylene
Ethylene is known to affect the following plant processes (Davies 1995 Mauseth 1991
Raven 1992 Salisbury and Ross 1992)
Stimulates the release of dormancy
Stimulates shoot and root growth and differentiation (triple response)
May have a role in adventitious root formation
Stimulates leaf and fruit abscission
Stimulates Bromiliad flower induction
Induction of femaleness in dioecious flowers
Stimulates flower opening
Stimulates flower and leaf senescence
Stimulates fruit ripening
Practical Application and its economic importance
Ethylene gas a wide variety of uses but its gaseous nature precludes its applications in
non-enclosed spaces Ethylene itself can be used to enhance the ripening of fruits such as
bananas in storage following their shipment in an unripe condition An ethylene-producing liquid
chemical 2-chloroethylphosphonic acid - commercially called Ethrel or Ethephon has been
introduced and it is sprayed onto the plant at a slightly acid pH When it enters the cells and
encounters the cytoplasm at about neutral pH it breaks down to release gaseous ethylene which
is commercially used for fruit ripening These hormones have a potential area of use in a wide
variety of fruits such as grapes cherries and citrus Promotion of female flower production in
cucurbits -cucumber squash and melon so as to increase the number of fruits produced per
plant It is also used for the promotion of flower initiation and controlled ripening in pineapples
Page 11 of 15
Economic Importance of Plant Growth Regulators
Other hormones
1 Florigen These hormones are synthesized in the older leaves and then transferred
to the growing region where it initiates the floral and bud initiation It is mainly
responsible for flowering in plants It also called flowering hormones
2 Anthesins Its newly discovered hormones responsible for flower formation
which horticulturists use to induce the early flowering in some plants
3 Vernalin It is used to undergo and bring nervalisation in some plants
4 Morphactins They are synthetic growth regulators which have the various roles
and functions as natural growth regulators It has been effective in flowering
stimulation sequence of flowering position and number of flowers formation of
flowers inflorescence parthenocarpy etc
Page 12 of 15
Economic Importance of Plant Growth Regulators
Conclusion
The plant growth regulators either synthetic or natural have been found great and wide
applications in agriculture and horticulture These growth regulators which in minute quantity
can have adverse effects to promote and modify a physiological process in plants On the
evidences of their adverse effects in small quantity these growth regulators have been found
greater applications and economic importance for farmers and horticulturists
The growth regulators are used to increase the fruit sizes to induce early flowering and
increase the number of flowering to break the dormancy of some seeds to quicken the maturity
and improve the fruit quality to increase the sugar content in sugarcane to increase the yield and
oil contents to promote the flower initiation and control ripening some other fruits and many
more Beside their major roles there are many other minor roles as sequence of flowering
position and number of flowers formation of flowers parthenocarpy root and shoot initiation
etc
The knowledge of these growth regulators have been advantages and boon to many
agriculturists and horticulturists globally Similarly we too can take advantages of their roles and
applications so as to make livelihood living and earn money some amount out of it Besides the
availability of these hormones in our places we too can go for it with the loaned investment
which is highly economic
In nutshell I would say that the plant growth regulators either synthetic or natural have
wide applications and uses for economical purposes and livelihood as well For it has been
found too crucial and economical to take the advantage of knowledge of the roles and
applications of growth regulators Theses growth regulators have been used widely in many other
countries unlike ours due to lack of access to the facilities
Therefore I request everyone to take advantage of its roles and applications and work for
economic purpose and livelihood Let us make use of those growth regulators
Page 13 of 15
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
Role of Ehtylene
Ethylene is known to affect the following plant processes (Davies 1995 Mauseth 1991
Raven 1992 Salisbury and Ross 1992)
Stimulates the release of dormancy
Stimulates shoot and root growth and differentiation (triple response)
May have a role in adventitious root formation
Stimulates leaf and fruit abscission
Stimulates Bromiliad flower induction
Induction of femaleness in dioecious flowers
Stimulates flower opening
Stimulates flower and leaf senescence
Stimulates fruit ripening
Practical Application and its economic importance
Ethylene gas a wide variety of uses but its gaseous nature precludes its applications in
non-enclosed spaces Ethylene itself can be used to enhance the ripening of fruits such as
bananas in storage following their shipment in an unripe condition An ethylene-producing liquid
chemical 2-chloroethylphosphonic acid - commercially called Ethrel or Ethephon has been
introduced and it is sprayed onto the plant at a slightly acid pH When it enters the cells and
encounters the cytoplasm at about neutral pH it breaks down to release gaseous ethylene which
is commercially used for fruit ripening These hormones have a potential area of use in a wide
variety of fruits such as grapes cherries and citrus Promotion of female flower production in
cucurbits -cucumber squash and melon so as to increase the number of fruits produced per
plant It is also used for the promotion of flower initiation and controlled ripening in pineapples
Page 11 of 15
Economic Importance of Plant Growth Regulators
Other hormones
1 Florigen These hormones are synthesized in the older leaves and then transferred
to the growing region where it initiates the floral and bud initiation It is mainly
responsible for flowering in plants It also called flowering hormones
2 Anthesins Its newly discovered hormones responsible for flower formation
which horticulturists use to induce the early flowering in some plants
3 Vernalin It is used to undergo and bring nervalisation in some plants
4 Morphactins They are synthetic growth regulators which have the various roles
and functions as natural growth regulators It has been effective in flowering
stimulation sequence of flowering position and number of flowers formation of
flowers inflorescence parthenocarpy etc
Page 12 of 15
Economic Importance of Plant Growth Regulators
Conclusion
The plant growth regulators either synthetic or natural have been found great and wide
applications in agriculture and horticulture These growth regulators which in minute quantity
can have adverse effects to promote and modify a physiological process in plants On the
evidences of their adverse effects in small quantity these growth regulators have been found
greater applications and economic importance for farmers and horticulturists
The growth regulators are used to increase the fruit sizes to induce early flowering and
increase the number of flowering to break the dormancy of some seeds to quicken the maturity
and improve the fruit quality to increase the sugar content in sugarcane to increase the yield and
oil contents to promote the flower initiation and control ripening some other fruits and many
more Beside their major roles there are many other minor roles as sequence of flowering
position and number of flowers formation of flowers parthenocarpy root and shoot initiation
etc
The knowledge of these growth regulators have been advantages and boon to many
agriculturists and horticulturists globally Similarly we too can take advantages of their roles and
applications so as to make livelihood living and earn money some amount out of it Besides the
availability of these hormones in our places we too can go for it with the loaned investment
which is highly economic
In nutshell I would say that the plant growth regulators either synthetic or natural have
wide applications and uses for economical purposes and livelihood as well For it has been
found too crucial and economical to take the advantage of knowledge of the roles and
applications of growth regulators Theses growth regulators have been used widely in many other
countries unlike ours due to lack of access to the facilities
Therefore I request everyone to take advantage of its roles and applications and work for
economic purpose and livelihood Let us make use of those growth regulators
Page 13 of 15
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
Other hormones
1 Florigen These hormones are synthesized in the older leaves and then transferred
to the growing region where it initiates the floral and bud initiation It is mainly
responsible for flowering in plants It also called flowering hormones
2 Anthesins Its newly discovered hormones responsible for flower formation
which horticulturists use to induce the early flowering in some plants
3 Vernalin It is used to undergo and bring nervalisation in some plants
4 Morphactins They are synthetic growth regulators which have the various roles
and functions as natural growth regulators It has been effective in flowering
stimulation sequence of flowering position and number of flowers formation of
flowers inflorescence parthenocarpy etc
Page 12 of 15
Economic Importance of Plant Growth Regulators
Conclusion
The plant growth regulators either synthetic or natural have been found great and wide
applications in agriculture and horticulture These growth regulators which in minute quantity
can have adverse effects to promote and modify a physiological process in plants On the
evidences of their adverse effects in small quantity these growth regulators have been found
greater applications and economic importance for farmers and horticulturists
The growth regulators are used to increase the fruit sizes to induce early flowering and
increase the number of flowering to break the dormancy of some seeds to quicken the maturity
and improve the fruit quality to increase the sugar content in sugarcane to increase the yield and
oil contents to promote the flower initiation and control ripening some other fruits and many
more Beside their major roles there are many other minor roles as sequence of flowering
position and number of flowers formation of flowers parthenocarpy root and shoot initiation
etc
The knowledge of these growth regulators have been advantages and boon to many
agriculturists and horticulturists globally Similarly we too can take advantages of their roles and
applications so as to make livelihood living and earn money some amount out of it Besides the
availability of these hormones in our places we too can go for it with the loaned investment
which is highly economic
In nutshell I would say that the plant growth regulators either synthetic or natural have
wide applications and uses for economical purposes and livelihood as well For it has been
found too crucial and economical to take the advantage of knowledge of the roles and
applications of growth regulators Theses growth regulators have been used widely in many other
countries unlike ours due to lack of access to the facilities
Therefore I request everyone to take advantage of its roles and applications and work for
economic purpose and livelihood Let us make use of those growth regulators
Page 13 of 15
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
Conclusion
The plant growth regulators either synthetic or natural have been found great and wide
applications in agriculture and horticulture These growth regulators which in minute quantity
can have adverse effects to promote and modify a physiological process in plants On the
evidences of their adverse effects in small quantity these growth regulators have been found
greater applications and economic importance for farmers and horticulturists
The growth regulators are used to increase the fruit sizes to induce early flowering and
increase the number of flowering to break the dormancy of some seeds to quicken the maturity
and improve the fruit quality to increase the sugar content in sugarcane to increase the yield and
oil contents to promote the flower initiation and control ripening some other fruits and many
more Beside their major roles there are many other minor roles as sequence of flowering
position and number of flowers formation of flowers parthenocarpy root and shoot initiation
etc
The knowledge of these growth regulators have been advantages and boon to many
agriculturists and horticulturists globally Similarly we too can take advantages of their roles and
applications so as to make livelihood living and earn money some amount out of it Besides the
availability of these hormones in our places we too can go for it with the loaned investment
which is highly economic
In nutshell I would say that the plant growth regulators either synthetic or natural have
wide applications and uses for economical purposes and livelihood as well For it has been
found too crucial and economical to take the advantage of knowledge of the roles and
applications of growth regulators Theses growth regulators have been used widely in many other
countries unlike ours due to lack of access to the facilities
Therefore I request everyone to take advantage of its roles and applications and work for
economic purpose and livelihood Let us make use of those growth regulators
Page 13 of 15
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
References
Devlin RM amp Witham FH (1986) Plant Physiology (1st ed) Delhi CBS PUBLISHERS amp
DISTRIBUTORS
Nature of auxins (nd) Retrieved on 21st September 2011 from
httpwwwplant-
hormonesinfoauxinshtm
Nature of abscisicacid (nd ) Retrieved on 21st September 2011 from
httpwwwplant- hormonesinfoabscisicacidhtm
Nature of cytokinins (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfocytokininshtm
Nature of ethylene (nd) Retrieved on 21st September 2011from
httpwwwplant-hormonesinfoethylenehtm
The Nature of Gibberellins (nd) Retrieved on 21st September 2011 from
httpwwwplant-hormonesinfogibberellinshtm
Pandey SD amp Sinha BK (2006) Plant Physiology (4th ed) Noida UP Vikas Publishing
House Pvt Ltd
Plant hormones (nd) Retrieved on 23rd September 2011 from
wwwbiog1105-1106orgdemos105unit5planthormonespdf
Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
httpextensionoregonstateedumgbotanyhormoneshtml
Rastogi VB (2011) A COMPLETE COURSE IN ISC BIOLOGY-VOLII New Delhi Pitambar
Page 14 of 15
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-
Economic Importance of Plant Growth Regulators
Publishing Company Pvt Ltd
Page 15 of 15
- Plant hormones and growth regulators (nd) Retrieved on 24th September 2011 from
-