Growth Regulators in Fruit Production

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Growth Regulators in Fruit Production

• www.Hortilover.com

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Plant Hormones

• Organic substances produced in the plant
• Translocated within plant
• Evokes response at low concentration

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Action of Hormones are Complex and Poorly
Understood

• Levels vary with plant tissue and developmental
  stage
• Effective concentrations vary with plant tissue
  and developmental stage
• Do not work alone - relative amounts of hormones
  are important

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Effect of Applied Hormones Depend on

• Species or cultivar
• Organ acted upon
• Timing of the spray
• Concentration absorbed

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Effect of Applied Hormones Depend on

• Species or cultivar
• Parthenocarpic set in pears
• Higher NAA needed to thin Golden Delicious vs.
  Red Delicious
• Less vigorous cultivars respond to a greater
  degree than vigorous trees
• Organ acted upon
• Timing of the spray
• Concentration absorbed

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Effect of Applied Hormones Depend on

• Species or cultivar
• Organ acted upon
• NAA applied to young fruit cause fruit drop
  (10-50 ppm)
• NAA applied to base of stem cause rooting (20-200
  ppm)
• Timing of the spray
• Concentration absorbed

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Auxin Concentration Effect on Plant Growth
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Effect of Applied Hormones Depend on

• Species or cultivar
• Organ acted upon
• Timing of the spray
• NAA applied to fruit (10 to 50 ppm)
• 20 days after bloom cause fruit drop
• 21 days before harvest prevent drop
• Concentration absorbed

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Effect of Applied Hormones Depend on

• Species or cultivar
• Organ acted upon
• Timing of the spray
• Concentration absorbed
• Concentration applied
• Absorption
• Environment Temperature and Moisture
• Plant cuticle
• Surfactants
• pH of water

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Types of Hormones

• Auxins
• IBA, NAA, NAD, IAA, 2,4-D
• Gibberellins
• Cytokinins
• BA, kinetin, zeatin, 2ip, TDZ
• Ethylene
• Ethrel, ethephon
• Growth Retardants
• SADH, PPP333, others

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Auxins

• Types
• IBA indolebutyric acid
• IAA indoleacetic acid
• NAA naphthalene acetic acid
• NAD naphthalene acetamide
• 2,4-D 2,4-dichlorophenoxyacetic acid
• Natural production
• Effects
• Examples of use

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Auxins

• Types
• Natural production
• Growing shoots and young leaves
• Developing embryos
• Effects
• Examples of use

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Auxins

• Types
• Natural production
• Effects
• Rate of cell enlargement
• Inhibit bud growth
• Stimulate cambial cell division
• Abscission of fruit
• Hasten ripening via ethylene production
• Stimulate rooting
• Examples of use

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Auxins

• Types
• Natural production
• Effects
• Examples of use
• NAA or NAD _at_ 5-50 ppm for thinning
• NAA to control preharvest drop
• NAA _at_ 1000 ppm to control root sprouts
• IBA _at_ 20-200 to stimulate the rooting of cuttings

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Gibberellins GA

• Natural production
• Very young leaves and embryos
• Fruits
• Roots
• Effects
• Stimulate cell elongation
• Prevent flower initiation
• Prevents abscission in young fruit
• Break rest in buds and seeds
• Examples of use

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Gibberellins

• Natural production
• Effects
• Examples of use
• Improve fruit shape in apple (with BA)
• Grapes
• Increase seedless set
• Increase fruit and cluster size
• Loosen clusters by pedicel elongation
• Delay harvest in cherry
• Reduce russetting on Golden Delicious

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Cytokinins

• Types
• BA benzylamino purine
• Kinetin 6, furfurylamino purine
• Zeatin
• 2iP 6-(?,?-dimethylallylamino) purine
• TDZ thidiazuron
• Natural production
• Effects
• Examples of use

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Cytokinins

• Natural production
• Roots
• Young fruits
• Effects
• Promote cell division
• Regulate apical dominance
• Promote branching
• Enhance fruit bud initiation
• Influence translocation
• Prevent Abscission/senescence

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Cytokinins

• Types
• Natural production
• Effects
• Examples of Use
• Promalin BA GA
• Increasing branching in apple (100-200 ppm)
• Increase fruit length in Red Delicious apple (25
  ppm 10days before full bloom)
• Induce shooting in tissue culture

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Ethylene

• Types
• Ethrel and ethephon
• Ethylene producing compounds
• Natural production
• Maturing to ripening fruit
• Injured tissue
• Effects
• Stimulates floral initiation
• Promotes abscission
• Increase respiration/maturation/coloring of fruit

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Ethylene Examples of Use

• Increase return bloom
• 100-1000 ppm _at_ early summer
• With NAD, thinning and return bloom
• 20-200 ppm _at_ 4-8 weeks after bloom
• Delay bloom with sweet cherry
• Sept. application
• Advance maturity in apple
• 250-500 ppm 1-2 weeks before harvest
• Induce abscission in apple, cranberry, grapes,
  nuts
• 500-1000 ppm 10 days before harvest

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Growth Retardants

• Alar SADH daminozide
• Used extensively in apple production
• Prevent preharvest drop
• Improve color and quality
• Control growth
• Increase set
• Taken off market by EPA in 1985
• Gibberellin biosynthesis inhibitors
• PPP333 Cultar Bonzai
• Not registered in USA for fruit production

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Common uses of Growth Regulators
DAFBdays after full bloom, BHbefore harvest,
FBfull bloom
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Any Questions about the use of PGR in fruit
production?