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Role of growth regulators in enhancing the productivity of vegetables

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Aziz-Ur-Rahman Jabarkhail

Growth regulators are organic compounds that modify or control specific physiological processes in plants. They include natural plant hormones like auxins, gibberellins, cytokinins, ethylene, and abscisic acid, as well as synthetic compounds. Growth regulators play various roles in vegetable crops including enhancing seed germination, breaking dormancy, inducing flowering and sex expression, stimulating fruit set and development, ripening, and increasing yields. Specifically, auxins like IAA and IBA and gibberellins promote germination, while gibberellins and ethylene break dormancy in potatoes and lettuce. Gibberellins, auxins, and cytokinins induce early flowering, and auxins, gibberell

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CREDIT SEMINAR ROLE OF GROWTH REGULATORS IN ENHANCING THE PRODUCTIVITY OF VEGETABLES Course Title : Master’s Seminar Course No. : VSC-591 SPEAKER AZIZ-UR-RAHMAN “JABARKHAIL” (A-2015-30-074)
Contents Introduction Definition and History of growth regulators(GR’s) Classification and Functions of growth regulators(GR’s) Role of GR’s in Vegetable Crops Case studies Precautions Constraints in the use of growth regulators Future thrust Conclusion 1
A growth regulator is •An organic compound, •Can be natural or synthetic, •It modifies or controls one or more specific physiological processes within a plant but the sites of action and production are different. If the compound is produced within the plant, it is called as plant hormone. Both internal plant hormones and lab created hormones are called plant growth regulators. INTRODUCTION 2
Definition of growth regulators (GR’s) by different Scientists Phillip (1971) defined growth hormone as substances which are synthesized in particular cells and are transferred to other cells where in extremely small quantities influence the developmental process. Phill Olaiya (2013) stated that bio-regulators are endogenous or synthetically produced substances that can control one or more specific biochemical and physiological functions of many species probably by their influence on gene and enzyme interactions. Prajapati et al., (2015) stated that although, photosynthesis supplies the carbon and respiration supplies the energy for plant growth, a group of chemicals produced by plants known as plant growth regulators control the growth and development of plant. . 3
Auxin was the first hormone to be discovered in plant and at one time considered to be only naturally occurring plant growth hormone. (Prajapati et al., 2015) Three types of plant hormones Auxins, Gibberellins and Cytokinins and these were discovered in the early decades of the twentieth century, in 1930’s and in 1960's respectively.(Thomas, 1956) History of Growth Regulators 4
Classification of growth regulators (GR’s) NATURAL GR’s SYNTHETIC GR’s e.g. 2,4- D, NAA, IBA, 2,4,5T, Morphactin, Cycocel, Maleic hydrazide etc. • Also produced spontaneously in the plant body, but their structure and function is not discovered clearly. e.g. Florigen,Vernalin. POSTULATED GR’s 1. ON THE BASIS OF ORIGIN (Meena, 2015) • Produced by some tissues in plant. • Also called Endogenous hormones. e.g. Auxins, Gibberellins Cytokinins, Ethylene Abscisic acid • Produced artificially and similar to natural hormone in physiological activity. •Also called •Exogenous hormones. 5
Sr. No. Growth regulator Example 1 Auxins IAA, IBA, NAA, 2,4-D 2 Gibberellins Gibberellic acid (GA, GA₃, GA₇) 3 Cytokinins Kinetin, Zeatin 4 Ethylene Ethylene, Ethephon, Ethrel 5 Dormins Abscisic Acid 6 Flowering hormones Florigen, Anthesin, Vernalin 9 Synthetic growth retardants CCC, Phosphon D, Morphactins, Maleic hydrazide (MH) etc. 10 Miscellaneous synthetic substances Synthetic auxins, synthetic cytokinins etc. Classification of growth regulators (GR’s) 6
Major group of plant growth regulators  Auxins  Gibberellins  Cytokinins  Ethylene  Abscisic acid Plant growth promoters Plant growth inhibitors 8
Plant Growth Promoters The word Auxins has been derived from a Greek word auxein- “to grow/increase”. It was first isolated from human urine. These are generally produced by the growing apex of stem and roots of the plants.. This was the first group of plant hormones discovered. Types of Auxin: I. Natural Auxin II. Synthetic Auxin Auxin IAA IBA, NAA, 2,4-D ( Meena, 2015 ) 8
 It causes cell elongation by loosening of the cell wall  Promotes secondary growth of stem through cambium activity  Promotes callus and root formation in cutting  Restores apical dominance  Induction of flowering  Increases fruit setting and size  Delays leaf abscission  Prevention of premature drop of fruits  Develops parthenocarpic fruits  Acts as herbicide at higher concentration  Inhibition of prolonged dormancy  Inhibiting aging processes in tissues. FUNCTIONS OF AUXINS 9
Second most important growth hormone. Gibberellins are named after the fungus Gibberella fujikuroi , which causes rice plants to grow abnormally tall . (Kurosawa et al., 1930) Gibberellin produced in the shoot apex mainly in the leaf primordial (leaf bud) and root system, hence they translocates easily in the plant in both directions. Now 135 different Gibberellins are available. The most commonly occurring gibberellins is GA3. GIBBERELLIN ( Meena, 2015) 10
 It induces maleness  Promotes growth of dwarf plants  Possesses pollenicide effect  Replaces chilling and light requirements of plants  Promotes seed germination  Used for breaking of dormancy  Delays senescence of Fruits  Enhances seedless fruits  For stem elongation  Accelerates flowering in long day plants  Intensifies transpiration, photosynthesis and respiration. FUNCTIONS OF GIBBERELLINS 11
They were first isolated from coconut milk. They are synthesized in root apex, endosperm of seeds, young fruits, where cell division takes place continuously. CYTOKININ 12
 Cell division.  Cell enlargement.  Induce flowering in short day plants.  Dormancy of certain light sensitive seeds such as lettuce can also be broken by kinetin treatment.  Delays leaf senescence.  Inhibit apical dominance and help in growth of lateral buds. Therefore, it is also known as anti-auxins. (Prajapati, 2015) Functions of Cytokinin 13
Ethylene is a colourless gaseous hormone.  Found in ripened fruits, flowers and leaves and nodes of stem.  Synthesis of ethylene is inhibited by carbon dioxide and requires oxygen. Ethylene 14 Growth Inhibitors
 Induces ripening of fruits. Promotes abscission and senescence of leaf, flowers etc.  Induction of Femaleness: cucumber, squash, melon.  It stimulates the formation of adventitious roots. Functions of Ethylene (Meena, 2015) 15
 It is also known as dormins, which acts as anti-Gibberellins.  It is synthesized in leaves of wide variety of plants.  Responsible for closing stomata during drought conditions, hence acts as plant stress hormone. ABSCISIC ACID 16
Promote tuberisation. Induces senescence of leaves, abscission of leaves, flowers and fruits. It induces dormancy of buds and seeds as opposed to Gibberellins, which breaks dormancy. It inhibits seed germination and development. ABA also plays important role in controlling stomata opening and closing. (Prajapati, 2015) Functions of Abscisic Acid 17
BRASSINOSTEROIDS • Brassinosteroids have been recognized as a sixth class of plant hormones. • Brassinolide was the first identified brassinosteroid and was isolated from extracts of rapeseed (Brassica napus) pollen in 1979. • It stimulate cell elongation and division, resistance to stresses. • They inhibit root growth and leaf abscission. Other Plant Growth Regulators 18
MORPHACTINS Morphactins are the group of substances which act on morphogenesis and modulate the expression of plants. Role of morphactins  Seed germination- inhibition. Growth of seedlings- inhibit. Stem elongation- dwarfing effect. 19
Commercial uses of bio- regulators in vegetable crops COMMERCIAL USE OF PLANT GROWTH REGULATORS IN VEGETABLE CROPS 20
 In tomato, pre sowing seed treatment with 100 ppm IAA, IBA and NAA enhanced the seed germination. (Olaiya et al.,2009)  In muskmelon, soaking of seeds in ethephon at 480 mg/litre of water for 24 hours improves germination in muskmelon at low temperature. (Meena, 2015) Tomato Muskmelon Okra SEED GERMINATION 21
 Pre-sowing treatment of seed with GA3 and KNO3 @ 50 ppm enhanced the germination of endive and chicory, respectively. (Tzortzakis, 2009)  IAA, NAA @ 20 ppm enhances seed germination in okra. (Khan et al., 2013) 22
 Seed dormancy is main problem in Potato and Lettuce. Chemicals which have been reported to break the rest period are GA3, Ethylene chlorhydrin and Thiourea. Lettuce is another vegetable in which treatment with GA3 or cytokinin has been reported to break seed dormancy induced by high temperature. SEED DORMANCY 23
 Soak the tubers in 1% aqueous solution of Thiourea for 1 hour or solution containing 5-10 ppm GA3 for 10- 20 minutes can be used to break the dormancy of potato. (Byran , 1989) Breaking the dormancy in potato comprise the vapour heat treatment with ethylene chlorhydrin (1 litre per 20 q) followed by dipping in thiourea (1% sol.) for 1h & finally in GA (1 mg/l) for 2 seconds. 24
 NAA 50 ppm has been reported to induce early flowering in paprika. ( Kannan et al., 2009)  Plants sprayed with 300 ppm GA3 were earliest to flower and recorded highest number of fruits and yield per plant in tomato.  Application of GA@50 mg/l to young leaves of non- flowering varieties of potato, when floral buds had just formed, resulted in flower induction in all varieties.  Gibberellic acid has been reported to induce early flowering in lettuce. ( Sharma et al.,1992) Flowering 25
 The treatment with growth regulators has been found to change sex expression in cucurbits, okra and pepper.  GA3 (10-25 ppm), IAA (100 ppm) and NAA (100 ppm) when sprayed at 2-4 leaf stage in cucurbits, then they have been found to increase the number of female flowers. ( Hume et al., 1983 )  Whereas, GA3 (1500-2000 ppm), silver nitrate (300-400 ppm) and silver thiosulphate (300-400 ppm) sprayed at 2-4 leaf stage induces male flower production in cucurbits. (Hatwal et al., 2015) Cucumber(F) Bitter gourd(F) Musk melon(F) Sponge gourd(F) Water melon(F) Cucumber(M) Musk melon(M) Water melon(M) Bitter gourd(M) Sponge gourd(M) Sex expression 26
Plant growth regulators helps to stimulate the fruit development without fertilization ( Parthenocarpy). 2,4-D at 50 ppm when applied at anthesis showed better performance over other in parthenocarpic fruit development in kakrol. ( Choudhury et al., 2007) Seed treatment with 2,4-D @ 2-5ppm gives early fruit set and leads to parthenocarpy in tomato. ( Meena, 2015) (Prajapati, 2015) Parthenocarpy 27
 Staminate flowers were induced in parthenocarpic line of cucumber through use of plant growth regulator GA3@ 1500 ppm and silver nitrate @ 200- 300ppm by four sprays at 4 days interval.  In brinjal, application of 2,4-D at 2.5ppm in lanolin paste to cut end of styles or as foliar sprays to freshly opened flower cluster has been reported to induced parthenocarpy. (Singh and Ram, 2004) 28
 Poor fruit set is a major problem in tomato, brinjal and chillies which is frequently caused by adverse weather conditions during flowering.  Plant growth regulators such as PCPA (20-25 ppm) and 2,4,-D (1-5 ppm), Kinetin (5 ppm), NAA (10 ppm) and GA3 (10 ppm) reported to enhance fruit set under both normal and adverse weather conditions, when applied at flowering stage in tomato, brinjal and chillies (Prajapati et all. 2015). Stimulation of fruit Set 29
Bioregulators have also been used for maintenance of gynoecious lines in cucurbits. Growth regulator like GA3 (1,500-2000ppm) and chemical like silver nitrate (200-300ppm) induces the male flowers on gynoecious cucumber . Exogenous application of silver thiosulphate (300-400ppm) induces the male flower in gynoecious muskmelon . ( Meena, 2015 ) Hybrid seed production 30
 Some PGR’s possesses gametocidal action to produce male sterility which can be used for F1 hybrid seed production.  MH at 100 to 500 ppm appeared most effective in inducing a high level of male sterility in eggplant, okra, peppers and tomato, without detrimental influence on female fertility. (Saimbhi et al., 1978)  A high concentration of gibberellic acid (2%) was found to act as a gametocide for the common onion (Allium cepa L.), when sprayed in the beginning of the bolting process. (Meer et al., 1973) Gametocides 31
Application of ethephon at 1000 mg/l at turning stage of earliest fruits induced early ripening of fruits thus increasing the early fruit yield by 30-35%. (Prajapati, 2015) Post-harvest dip treatment with ethephon at 500-2000 mg/l has also been reported to induce ripening in mature green tomatoes. (Gould, 1992) FRUIT RIPENING 32
FRUIT YIELD 1. TOMATO Spraying with 60 ppm GA3 10 days before transplanting increased the yield per ha of variety Roma. ( Naeem et al., 2001)  Spray with 6ppm 2,4-D gave highest yield of tomato. ( Patel et al., 2014) 2. BRINJAL  Foliar sprays of 2,4-D @4 ppm gave the highest yield of brinjal.(Patel et al., 2012)  Seed treatment with 10ppm GA3 or IAA gave the highest yield in brinjal. (Sharma et al., 1992) 3. CHILLI  Foliar sprays of 2 ppm 2,4-D, 40 ppm NAA and 10 ppm GA3 gave 28.75%, 13.61% and 2.30% higher fruit yield over control, respectively.(Choudhaury et al., 2006)  Spraying plants with 10 ppm NAA gave significantly highest fruit yield (277.8 g/plant). ( Sultana et al., 2006) 33
Case studies 34
TREAT - MENTS PERCENT FRUIT SET NO. OF FRUITS/ PLANT FRUIT WEIGHT (g) FRUIT LENGTH (cm) FRUIT WIDTH (cm) RIND THICKNESS (cm) FRUIT YIELD (q/ha) Control 30.6 13.2 80.5 4.3 4.4 0.40 380.7 GA3 20 ppm 35.4 18.7 85.1 4.8 4.92 0.45 396.2 GA3 40 ppm 40.2 22.7 120.2 5.06 5.21 0.48 418.6 GA3 60 ppm 47.3 26.2 125.7 5.92 6.20 0.52 446.5 GA3 80 ppm 51.6 30.2 130.8 6.46 6.86 0.56 483.6 NAA 25 ppm 32.1 18.5 84.1 4.6 4.72 0.44 390.5 NAA 50 ppm 37.7 21.7 118.2 4.82 4.90 0.45 402.7 NAA 75 ppm 44.5 23.4 121.8 5.78 6.11 0.50 433.6 NAA 100 ppm 49.1 24.7 128.6 6.08 6.38 0.55 474.2 CD (0.05) 3.42 9.50 6.48 1.01 NS 1.23 12.6 35 2013
Treatments Plant height (cm) No. of leaves Days to central head formation Days to secondary head formation Total yield /ha(q) GA3 20 ppm 60.73 13.73 61.40 70.93 169.80 GA3 40 ppm 63.07 13.47 61.53 71.33 175.29 GA3 60 ppm 60.93 14.53 57.86 66.20 176.11 kinetin 20 ppm 55.40 14.80 59.86 69.60 163.88 kinetin 40 ppm 61.47 15.67 59.87 69.93 174.94 kinetin 60 ppm 60.80 14.53 60.40 71.60 185.16 GA3 10 ppm + kinetin 10 ppm 59.67 15.33 58.86 69.60 170.58 GA3 20 ppm + kinetin 20 ppm 57.843 15.20 61.13 71.53 187.05 GA3 30 ppm + kinetin 30 ppm 63.77 16.00 60.73 70.06 189.67 Control 58.27 13.33 63.60 74.53 145.15 C.D at 5% 5.09 2.01 2.62 2.94 42.24 36 2011
Growth Regulators Concentration (ppm) Method of Application Crops Effect on Quality GA3 15 Foliar spray Muskmelon Improve rind thickness GA3 5-15 Foliar spray Cauliflower, cabbage Increases head or curd size GA3 50 Foliar spray Lettuce and Chinese cabbage Increases dry matter, protein and ascorbic acid content PCPA 50 Foliar spray Tomato Increases sugar and vitamin-C, but reduces acidity EFFECT OF GROWTH REGULATORS ON QUALITY OF VEGETABLE 37
Contd… CCC 250 Foliar spray Potato Increases TSS and vitamin-C content in tuber Cytozyme 1% Foliar spray Garden pea Increases vitamin-C, reducing sugars and total sugars Ethephon 250 Foliar spray Tomato Increases TSS NAA 50-70 Seed treatment Chilli Increases amino acid and vitamin- C content in fruits (Bahadur and Singh, 2014) 38
GROWTH REGULATORS CONC. (mg/l) METHOD OF APPLICATIO N CROPS ATTRIBUTES AFFECTED Cycocel (CCC) 250-500 Foliar spray Cucurbits,tomato, okra Flowering, sex expression, fruit yield P-Chlorophenoxy Acetic acid (PCPA) 50 Foliar spray Tomato Fruit set and Yield Ethephon (CEPA) 100-500 Foliar spray Cucurbits, okra and tomato Flowering, fruiting, sex expression and yield 2000 Post- harvest Tomato, chillies Fruit ripening Gibberellic acid (GA) 10 Foliar spray Water melon, tomato Sex expression, fruiting ,yield Indoleacetic acid (IAA) 10-15 Foliar spray Okra, tomato, brinjal, Seed germination, fruit set and yield List of plant growth regulators and their important uses in vegetable crops Contd… 39
Naphthalene acetic acid (NAA) 20 Seedling roots Tomato, Brinjal, Onion Growth and yield 10-20 Foliar sprays Chillies and Tomato Flower drop, fruit set and yield 25-30 Seed/ foliar Okra ,Tomato, Brinjal, Onion, Cucurbits Seed germination, growth and yield Naphthoxyacet-ic acid (NOA) 25-100 Seed/ foliar Tomato, Okra Germination, growth and yield Silver nitrate 500 Foliar spray Cucumber Induction of male flower in gynoecious lines Silver thiosulphate 400 Foliar spray Musk melon Induction of male flower in gynoecious lines 2,3-5, tri- iodobenzoic acid (TIBA) 25-50 Foliar sprays Cucurbits Flowering, sex expression and yield Tricontanol 2 Foliar sprays Chillies and Peas Fruit set and yield Source :Chadha and Kalloo,1993 40
Growth substances should be sprayed preferably in the evening hours.  Avoid to spray in windy hours. Spray should be uniform and wet both the surface of leaves. Use growth substances at an appropriate stage of plant growth is of great importance. Chemical should be completely dissolved before application. Precaution in Growth Regulator Application 41 Conti….
Use always fresh solution of chemicals. Use PGR’s strictly at recommended concentration. Solution should always be prepared in distilled water only. Fine spray can be ensured by hand automizer. It is most economical and effective method of spray. Wash the machine/pump after each spray. Repeat the spray within eight hours, if chemical is wash out due to rain. 42 Conti….
The difference in sensitivity of each plant species or even cultivars to a given chemical treatment prevent easy predication of the biological effects. The cost of developing new plants growth regulator is very high, due to which they are very much costly. Screening for plant growth regulatory activities entails high costs and is very much difficult. Constraints in the use of growth regulators 43 Conti….
Some synthetic plant growth regulators cause human health hazards e.g. Dominozide. Lack of basic knowledge of toxicity and mechanism of action. Inadequate market potential. Lack of support from agricultural researchers in public and private sectors. Difficulty in identification of proper stage of crop at which the growth regulators should be applied. 44 Conti….
Most of the biological processes associated are polygenic, so gene transfer may be difficult and hence the use of PGR’s may be beneficial for short imperatives. PGR’s provide an immediate impact on crop improvement programmes and are less time consuming. Applications of PGR’s must lead to quantifiable advantages for the user. Industries involved in development of PGR’s should be well informed about the latest scientific development in production of PGR’s. Future thrust 45 Conti….
Plant growth regulators should be recognized as more than academic curiosities. They are not only interesting but profitable to use to grower, distributor and manufacturer. More research is needed to develop simple, economical and technical viable production systems of PGR’s. 46 Conti….
Conclusion Plant growth regulators has an immense potential in vegetable production to increase the yield, quality, synchronization in flowering, earliness, cold and high temperature fruit setting, sex modification, increase post-harvest life and resistance to biotic and abiotic stresses of vegetables to better meet the requirements of food supply in general. But more research is needed to develop simple, economical and technical viable production system of bio-regulator. Bio-regulators must be toxicologically and environmentally safe. 47
Role of growth regulators in enhancing the productivity of vegetables

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Role of growth regulators in enhancing the productivity of vegetables

  • 1. CREDIT SEMINAR ROLE OF GROWTH REGULATORS IN ENHANCING THE PRODUCTIVITY OF VEGETABLES Course Title : Master’s Seminar Course No. : VSC-591 SPEAKER AZIZ-UR-RAHMAN “JABARKHAIL” (A-2015-30-074)
  • 2. Contents Introduction Definition and History of growth regulators(GR’s) Classification and Functions of growth regulators(GR’s) Role of GR’s in Vegetable Crops Case studies Precautions Constraints in the use of growth regulators Future thrust Conclusion 1
  • 3. A growth regulator is •An organic compound, •Can be natural or synthetic, •It modifies or controls one or more specific physiological processes within a plant but the sites of action and production are different. If the compound is produced within the plant, it is called as plant hormone. Both internal plant hormones and lab created hormones are called plant growth regulators. INTRODUCTION 2
  • 4. Definition of growth regulators (GR’s) by different Scientists Phillip (1971) defined growth hormone as substances which are synthesized in particular cells and are transferred to other cells where in extremely small quantities influence the developmental process. Phill Olaiya (2013) stated that bio-regulators are endogenous or synthetically produced substances that can control one or more specific biochemical and physiological functions of many species probably by their influence on gene and enzyme interactions. Prajapati et al., (2015) stated that although, photosynthesis supplies the carbon and respiration supplies the energy for plant growth, a group of chemicals produced by plants known as plant growth regulators control the growth and development of plant. . 3
  • 5. Auxin was the first hormone to be discovered in plant and at one time considered to be only naturally occurring plant growth hormone. (Prajapati et al., 2015) Three types of plant hormones Auxins, Gibberellins and Cytokinins and these were discovered in the early decades of the twentieth century, in 1930’s and in 1960's respectively.(Thomas, 1956) History of Growth Regulators 4
  • 6. Classification of growth regulators (GR’s) NATURAL GR’s SYNTHETIC GR’s e.g. 2,4- D, NAA, IBA, 2,4,5T, Morphactin, Cycocel, Maleic hydrazide etc. • Also produced spontaneously in the plant body, but their structure and function is not discovered clearly. e.g. Florigen,Vernalin. POSTULATED GR’s 1. ON THE BASIS OF ORIGIN (Meena, 2015) • Produced by some tissues in plant. • Also called Endogenous hormones. e.g. Auxins, Gibberellins Cytokinins, Ethylene Abscisic acid • Produced artificially and similar to natural hormone in physiological activity. •Also called •Exogenous hormones. 5
  • 7. Sr. No. Growth regulator Example 1 Auxins IAA, IBA, NAA, 2,4-D 2 Gibberellins Gibberellic acid (GA, GA₃, GA₇) 3 Cytokinins Kinetin, Zeatin 4 Ethylene Ethylene, Ethephon, Ethrel 5 Dormins Abscisic Acid 6 Flowering hormones Florigen, Anthesin, Vernalin 9 Synthetic growth retardants CCC, Phosphon D, Morphactins, Maleic hydrazide (MH) etc. 10 Miscellaneous synthetic substances Synthetic auxins, synthetic cytokinins etc. Classification of growth regulators (GR’s) 6
  • 8. Major group of plant growth regulators  Auxins  Gibberellins  Cytokinins  Ethylene  Abscisic acid Plant growth promoters Plant growth inhibitors 8
  • 9. Plant Growth Promoters The word Auxins has been derived from a Greek word auxein- “to grow/increase”. It was first isolated from human urine. These are generally produced by the growing apex of stem and roots of the plants.. This was the first group of plant hormones discovered. Types of Auxin: I. Natural Auxin II. Synthetic Auxin Auxin IAA IBA, NAA, 2,4-D ( Meena, 2015 ) 8
  • 10.  It causes cell elongation by loosening of the cell wall  Promotes secondary growth of stem through cambium activity  Promotes callus and root formation in cutting  Restores apical dominance  Induction of flowering  Increases fruit setting and size  Delays leaf abscission  Prevention of premature drop of fruits  Develops parthenocarpic fruits  Acts as herbicide at higher concentration  Inhibition of prolonged dormancy  Inhibiting aging processes in tissues. FUNCTIONS OF AUXINS 9
  • 11. Second most important growth hormone. Gibberellins are named after the fungus Gibberella fujikuroi , which causes rice plants to grow abnormally tall . (Kurosawa et al., 1930) Gibberellin produced in the shoot apex mainly in the leaf primordial (leaf bud) and root system, hence they translocates easily in the plant in both directions. Now 135 different Gibberellins are available. The most commonly occurring gibberellins is GA3. GIBBERELLIN ( Meena, 2015) 10
  • 12.  It induces maleness  Promotes growth of dwarf plants  Possesses pollenicide effect  Replaces chilling and light requirements of plants  Promotes seed germination  Used for breaking of dormancy  Delays senescence of Fruits  Enhances seedless fruits  For stem elongation  Accelerates flowering in long day plants  Intensifies transpiration, photosynthesis and respiration. FUNCTIONS OF GIBBERELLINS 11
  • 13. They were first isolated from coconut milk. They are synthesized in root apex, endosperm of seeds, young fruits, where cell division takes place continuously. CYTOKININ 12
  • 14.  Cell division.  Cell enlargement.  Induce flowering in short day plants.  Dormancy of certain light sensitive seeds such as lettuce can also be broken by kinetin treatment.  Delays leaf senescence.  Inhibit apical dominance and help in growth of lateral buds. Therefore, it is also known as anti-auxins. (Prajapati, 2015) Functions of Cytokinin 13
  • 15. Ethylene is a colourless gaseous hormone.  Found in ripened fruits, flowers and leaves and nodes of stem.  Synthesis of ethylene is inhibited by carbon dioxide and requires oxygen. Ethylene 14 Growth Inhibitors
  • 16.  Induces ripening of fruits. Promotes abscission and senescence of leaf, flowers etc.  Induction of Femaleness: cucumber, squash, melon.  It stimulates the formation of adventitious roots. Functions of Ethylene (Meena, 2015) 15
  • 17.  It is also known as dormins, which acts as anti-Gibberellins.  It is synthesized in leaves of wide variety of plants.  Responsible for closing stomata during drought conditions, hence acts as plant stress hormone. ABSCISIC ACID 16
  • 18. Promote tuberisation. Induces senescence of leaves, abscission of leaves, flowers and fruits. It induces dormancy of buds and seeds as opposed to Gibberellins, which breaks dormancy. It inhibits seed germination and development. ABA also plays important role in controlling stomata opening and closing. (Prajapati, 2015) Functions of Abscisic Acid 17
  • 19. BRASSINOSTEROIDS • Brassinosteroids have been recognized as a sixth class of plant hormones. • Brassinolide was the first identified brassinosteroid and was isolated from extracts of rapeseed (Brassica napus) pollen in 1979. • It stimulate cell elongation and division, resistance to stresses. • They inhibit root growth and leaf abscission. Other Plant Growth Regulators 18
  • 20. MORPHACTINS Morphactins are the group of substances which act on morphogenesis and modulate the expression of plants. Role of morphactins  Seed germination- inhibition. Growth of seedlings- inhibit. Stem elongation- dwarfing effect. 19
  • 21. Commercial uses of bio- regulators in vegetable crops COMMERCIAL USE OF PLANT GROWTH REGULATORS IN VEGETABLE CROPS 20
  • 22.  In tomato, pre sowing seed treatment with 100 ppm IAA, IBA and NAA enhanced the seed germination. (Olaiya et al.,2009)  In muskmelon, soaking of seeds in ethephon at 480 mg/litre of water for 24 hours improves germination in muskmelon at low temperature. (Meena, 2015) Tomato Muskmelon Okra SEED GERMINATION 21
  • 23.  Pre-sowing treatment of seed with GA3 and KNO3 @ 50 ppm enhanced the germination of endive and chicory, respectively. (Tzortzakis, 2009)  IAA, NAA @ 20 ppm enhances seed germination in okra. (Khan et al., 2013) 22
  • 24.  Seed dormancy is main problem in Potato and Lettuce. Chemicals which have been reported to break the rest period are GA3, Ethylene chlorhydrin and Thiourea. Lettuce is another vegetable in which treatment with GA3 or cytokinin has been reported to break seed dormancy induced by high temperature. SEED DORMANCY 23
  • 25.  Soak the tubers in 1% aqueous solution of Thiourea for 1 hour or solution containing 5-10 ppm GA3 for 10- 20 minutes can be used to break the dormancy of potato. (Byran , 1989) Breaking the dormancy in potato comprise the vapour heat treatment with ethylene chlorhydrin (1 litre per 20 q) followed by dipping in thiourea (1% sol.) for 1h & finally in GA (1 mg/l) for 2 seconds. 24
  • 26.  NAA 50 ppm has been reported to induce early flowering in paprika. ( Kannan et al., 2009)  Plants sprayed with 300 ppm GA3 were earliest to flower and recorded highest number of fruits and yield per plant in tomato.  Application of GA@50 mg/l to young leaves of non- flowering varieties of potato, when floral buds had just formed, resulted in flower induction in all varieties.  Gibberellic acid has been reported to induce early flowering in lettuce. ( Sharma et al.,1992) Flowering 25
  • 27.  The treatment with growth regulators has been found to change sex expression in cucurbits, okra and pepper.  GA3 (10-25 ppm), IAA (100 ppm) and NAA (100 ppm) when sprayed at 2-4 leaf stage in cucurbits, then they have been found to increase the number of female flowers. ( Hume et al., 1983 )  Whereas, GA3 (1500-2000 ppm), silver nitrate (300-400 ppm) and silver thiosulphate (300-400 ppm) sprayed at 2-4 leaf stage induces male flower production in cucurbits. (Hatwal et al., 2015) Cucumber(F) Bitter gourd(F) Musk melon(F) Sponge gourd(F) Water melon(F) Cucumber(M) Musk melon(M) Water melon(M) Bitter gourd(M) Sponge gourd(M) Sex expression 26
  • 28. Plant growth regulators helps to stimulate the fruit development without fertilization ( Parthenocarpy). 2,4-D at 50 ppm when applied at anthesis showed better performance over other in parthenocarpic fruit development in kakrol. ( Choudhury et al., 2007) Seed treatment with 2,4-D @ 2-5ppm gives early fruit set and leads to parthenocarpy in tomato. ( Meena, 2015) (Prajapati, 2015) Parthenocarpy 27
  • 29.  Staminate flowers were induced in parthenocarpic line of cucumber through use of plant growth regulator GA3@ 1500 ppm and silver nitrate @ 200- 300ppm by four sprays at 4 days interval.  In brinjal, application of 2,4-D at 2.5ppm in lanolin paste to cut end of styles or as foliar sprays to freshly opened flower cluster has been reported to induced parthenocarpy. (Singh and Ram, 2004) 28
  • 30.  Poor fruit set is a major problem in tomato, brinjal and chillies which is frequently caused by adverse weather conditions during flowering.  Plant growth regulators such as PCPA (20-25 ppm) and 2,4,-D (1-5 ppm), Kinetin (5 ppm), NAA (10 ppm) and GA3 (10 ppm) reported to enhance fruit set under both normal and adverse weather conditions, when applied at flowering stage in tomato, brinjal and chillies (Prajapati et all. 2015). Stimulation of fruit Set 29
  • 31. Bioregulators have also been used for maintenance of gynoecious lines in cucurbits. Growth regulator like GA3 (1,500-2000ppm) and chemical like silver nitrate (200-300ppm) induces the male flowers on gynoecious cucumber . Exogenous application of silver thiosulphate (300-400ppm) induces the male flower in gynoecious muskmelon . ( Meena, 2015 ) Hybrid seed production 30
  • 32.  Some PGR’s possesses gametocidal action to produce male sterility which can be used for F1 hybrid seed production.  MH at 100 to 500 ppm appeared most effective in inducing a high level of male sterility in eggplant, okra, peppers and tomato, without detrimental influence on female fertility. (Saimbhi et al., 1978)  A high concentration of gibberellic acid (2%) was found to act as a gametocide for the common onion (Allium cepa L.), when sprayed in the beginning of the bolting process. (Meer et al., 1973) Gametocides 31
  • 33. Application of ethephon at 1000 mg/l at turning stage of earliest fruits induced early ripening of fruits thus increasing the early fruit yield by 30-35%. (Prajapati, 2015) Post-harvest dip treatment with ethephon at 500-2000 mg/l has also been reported to induce ripening in mature green tomatoes. (Gould, 1992) FRUIT RIPENING 32
  • 34. FRUIT YIELD 1. TOMATO Spraying with 60 ppm GA3 10 days before transplanting increased the yield per ha of variety Roma. ( Naeem et al., 2001)  Spray with 6ppm 2,4-D gave highest yield of tomato. ( Patel et al., 2014) 2. BRINJAL  Foliar sprays of 2,4-D @4 ppm gave the highest yield of brinjal.(Patel et al., 2012)  Seed treatment with 10ppm GA3 or IAA gave the highest yield in brinjal. (Sharma et al., 1992) 3. CHILLI  Foliar sprays of 2 ppm 2,4-D, 40 ppm NAA and 10 ppm GA3 gave 28.75%, 13.61% and 2.30% higher fruit yield over control, respectively.(Choudhaury et al., 2006)  Spraying plants with 10 ppm NAA gave significantly highest fruit yield (277.8 g/plant). ( Sultana et al., 2006) 33
  • 36. TREAT - MENTS PERCENT FRUIT SET NO. OF FRUITS/ PLANT FRUIT WEIGHT (g) FRUIT LENGTH (cm) FRUIT WIDTH (cm) RIND THICKNESS (cm) FRUIT YIELD (q/ha) Control 30.6 13.2 80.5 4.3 4.4 0.40 380.7 GA3 20 ppm 35.4 18.7 85.1 4.8 4.92 0.45 396.2 GA3 40 ppm 40.2 22.7 120.2 5.06 5.21 0.48 418.6 GA3 60 ppm 47.3 26.2 125.7 5.92 6.20 0.52 446.5 GA3 80 ppm 51.6 30.2 130.8 6.46 6.86 0.56 483.6 NAA 25 ppm 32.1 18.5 84.1 4.6 4.72 0.44 390.5 NAA 50 ppm 37.7 21.7 118.2 4.82 4.90 0.45 402.7 NAA 75 ppm 44.5 23.4 121.8 5.78 6.11 0.50 433.6 NAA 100 ppm 49.1 24.7 128.6 6.08 6.38 0.55 474.2 CD (0.05) 3.42 9.50 6.48 1.01 NS 1.23 12.6 35 2013
  • 37. Treatments Plant height (cm) No. of leaves Days to central head formation Days to secondary head formation Total yield /ha(q) GA3 20 ppm 60.73 13.73 61.40 70.93 169.80 GA3 40 ppm 63.07 13.47 61.53 71.33 175.29 GA3 60 ppm 60.93 14.53 57.86 66.20 176.11 kinetin 20 ppm 55.40 14.80 59.86 69.60 163.88 kinetin 40 ppm 61.47 15.67 59.87 69.93 174.94 kinetin 60 ppm 60.80 14.53 60.40 71.60 185.16 GA3 10 ppm + kinetin 10 ppm 59.67 15.33 58.86 69.60 170.58 GA3 20 ppm + kinetin 20 ppm 57.843 15.20 61.13 71.53 187.05 GA3 30 ppm + kinetin 30 ppm 63.77 16.00 60.73 70.06 189.67 Control 58.27 13.33 63.60 74.53 145.15 C.D at 5% 5.09 2.01 2.62 2.94 42.24 36 2011
  • 38. Growth Regulators Concentration (ppm) Method of Application Crops Effect on Quality GA3 15 Foliar spray Muskmelon Improve rind thickness GA3 5-15 Foliar spray Cauliflower, cabbage Increases head or curd size GA3 50 Foliar spray Lettuce and Chinese cabbage Increases dry matter, protein and ascorbic acid content PCPA 50 Foliar spray Tomato Increases sugar and vitamin-C, but reduces acidity EFFECT OF GROWTH REGULATORS ON QUALITY OF VEGETABLE 37
  • 39. Contd… CCC 250 Foliar spray Potato Increases TSS and vitamin-C content in tuber Cytozyme 1% Foliar spray Garden pea Increases vitamin-C, reducing sugars and total sugars Ethephon 250 Foliar spray Tomato Increases TSS NAA 50-70 Seed treatment Chilli Increases amino acid and vitamin- C content in fruits (Bahadur and Singh, 2014) 38
  • 40. GROWTH REGULATORS CONC. (mg/l) METHOD OF APPLICATIO N CROPS ATTRIBUTES AFFECTED Cycocel (CCC) 250-500 Foliar spray Cucurbits,tomato, okra Flowering, sex expression, fruit yield P-Chlorophenoxy Acetic acid (PCPA) 50 Foliar spray Tomato Fruit set and Yield Ethephon (CEPA) 100-500 Foliar spray Cucurbits, okra and tomato Flowering, fruiting, sex expression and yield 2000 Post- harvest Tomato, chillies Fruit ripening Gibberellic acid (GA) 10 Foliar spray Water melon, tomato Sex expression, fruiting ,yield Indoleacetic acid (IAA) 10-15 Foliar spray Okra, tomato, brinjal, Seed germination, fruit set and yield List of plant growth regulators and their important uses in vegetable crops Contd… 39
  • 41. Naphthalene acetic acid (NAA) 20 Seedling roots Tomato, Brinjal, Onion Growth and yield 10-20 Foliar sprays Chillies and Tomato Flower drop, fruit set and yield 25-30 Seed/ foliar Okra ,Tomato, Brinjal, Onion, Cucurbits Seed germination, growth and yield Naphthoxyacet-ic acid (NOA) 25-100 Seed/ foliar Tomato, Okra Germination, growth and yield Silver nitrate 500 Foliar spray Cucumber Induction of male flower in gynoecious lines Silver thiosulphate 400 Foliar spray Musk melon Induction of male flower in gynoecious lines 2,3-5, tri- iodobenzoic acid (TIBA) 25-50 Foliar sprays Cucurbits Flowering, sex expression and yield Tricontanol 2 Foliar sprays Chillies and Peas Fruit set and yield Source :Chadha and Kalloo,1993 40
  • 42. Growth substances should be sprayed preferably in the evening hours.  Avoid to spray in windy hours. Spray should be uniform and wet both the surface of leaves. Use growth substances at an appropriate stage of plant growth is of great importance. Chemical should be completely dissolved before application. Precaution in Growth Regulator Application 41 Conti….
  • 43. Use always fresh solution of chemicals. Use PGR’s strictly at recommended concentration. Solution should always be prepared in distilled water only. Fine spray can be ensured by hand automizer. It is most economical and effective method of spray. Wash the machine/pump after each spray. Repeat the spray within eight hours, if chemical is wash out due to rain. 42 Conti….
  • 44. The difference in sensitivity of each plant species or even cultivars to a given chemical treatment prevent easy predication of the biological effects. The cost of developing new plants growth regulator is very high, due to which they are very much costly. Screening for plant growth regulatory activities entails high costs and is very much difficult. Constraints in the use of growth regulators 43 Conti….
  • 45. Some synthetic plant growth regulators cause human health hazards e.g. Dominozide. Lack of basic knowledge of toxicity and mechanism of action. Inadequate market potential. Lack of support from agricultural researchers in public and private sectors. Difficulty in identification of proper stage of crop at which the growth regulators should be applied. 44 Conti….
  • 46. Most of the biological processes associated are polygenic, so gene transfer may be difficult and hence the use of PGR’s may be beneficial for short imperatives. PGR’s provide an immediate impact on crop improvement programmes and are less time consuming. Applications of PGR’s must lead to quantifiable advantages for the user. Industries involved in development of PGR’s should be well informed about the latest scientific development in production of PGR’s. Future thrust 45 Conti….
  • 47. Plant growth regulators should be recognized as more than academic curiosities. They are not only interesting but profitable to use to grower, distributor and manufacturer. More research is needed to develop simple, economical and technical viable production systems of PGR’s. 46 Conti….
  • 48. Conclusion Plant growth regulators has an immense potential in vegetable production to increase the yield, quality, synchronization in flowering, earliness, cold and high temperature fruit setting, sex modification, increase post-harvest life and resistance to biotic and abiotic stresses of vegetables to better meet the requirements of food supply in general. But more research is needed to develop simple, economical and technical viable production system of bio-regulator. Bio-regulators must be toxicologically and environmentally safe. 47

Editor's Notes

  1. Cytokinin induce cell division especially in carrot root tissue, pea callus etc Cytokinin may also induces cell enlargement in the leaves of Phaseolus vulgaris, pumpkin cotyledons etc.
  2. Pre-sowing treatment of seed with growth regulators has been reported to enhance seed emergence. In tomato, pre sowing seed treatment with 100 ppm IAA, IBA and NAA enhanced the seed germination .
  3. Induction of flowering which otherwise fails to flower has also been reported with the use of various growth regulators.
  4. Poor fruit set is a major problem in tomato, brinjal and chillies which is frequently caused by adverse weather conditions during flowering.
  5. Ethephon, an ethylene releasing compound, has been reported to induce ripening in tomato and pepper. (Prajapati, 2015)