Plant Growth Regulators

Plant Growth Regulators

Plant Growth Regulators

are naturally occurring or synthetic compounds that affect plant growth

and development

Plant Growth Regulators

are naturally occurring or synthetic compounds that affect plant growth

and development

3 Types of Chemical Plant Growth Regulators

3 Types of Chemical Plant Growth Regulators

Growth-inhibiting Growth-inhibiting chemicalschemicals

Growth-promoting Growth-promoting chemicalschemicals

Root-promoting chemicalsRoot-promoting chemicals

Plant Hormones“Chemical Messengers”

Plant Hormones“Chemical Messengers”

AuxinsAuxins Cytokinins Cytokinins GibberellinsGibberellins EthyleneEthylene

Rooting HormonesRooting Hormones

Auxin, which stimulates rooting, is Auxin, which stimulates rooting, is the main component the main component

IAA (indoleacetic acid) IAA (indoleacetic acid) IBA (indolebutyric acid) IBA (indolebutyric acid) NAA (naphthaleneacetic acid)NAA (naphthaleneacetic acid)

Rooting HormonesRooting Hormones

Combination of IBA and NAACombination of IBA and NAA Powder FormulationsPowder Formulations

HormodinHormodin Hormo-RootHormo-Root Rhizopon AARhizopon AA

Liquid FormulationsLiquid Formulations Woods Rooting CompoundWoods Rooting Compound Dip’ N GrowDip’ N Grow

Liquid HormonesLiquid Hormones

Powder HormonesPowder Hormones

CytokininsCytokinins

Responsible for shoot initiationResponsible for shoot initiation Present in rapidly dividing tissuePresent in rapidly dividing tissue Benzyladenine (BA) Benzyladenine (BA)

synthetic cytokininsynthetic cytokinin increases offset formation in hostaincreases offset formation in hosta

Gibberellic Acid (GA)Gibberellic Acid (GA)

Promotes cellular elongation Promotes cellular elongation (stretched internodes)(stretched internodes)

Increases fruit setIncreases fruit set Pro-GibbPro-Gibb: Enlarges flowers and : Enlarges flowers and

elongates peduncles (stems elongates peduncles (stems supporting flowers)supporting flowers)

Ethylene GasEthylene Gas

Affects cell division and Affects cell division and developmentdevelopment

Cause floweringCause flowering Causes fruit ripeningCauses fruit ripening Causes leaf abscissionCauses leaf abscission

Plant Growth Retardants (PGRs)

are any chemicals that slow cell division and elongation in shoot

tissues

Plant Growth Retardants (PGRs)

are any chemicals that slow cell division and elongation in shoot

tissues

Why Control Growth?Why Control Growth?

Blow-overBlow-over Plants out-grow potsPlants out-grow pots Watering becomes difficultWatering becomes difficult Increased shipping costsIncreased shipping costs Leggy, low quality plantsLeggy, low quality plants

Methods of Growth ControlMethods of Growth Control

PruningPruning costly and time consumingcostly and time consuming

GeneticsGenetics not always availablenot always available consumers wary of GMOsconsumers wary of GMOs

Methods of Growth ControlMethods of Growth Control

Environmental controlsEnvironmental controlsLow fertilityLow fertilityNegative DIF (Temp)Negative DIF (Temp)Water StressWater StressBrushing, vibrations, and other Brushing, vibrations, and other

mechanical disturbancesmechanical disturbances

Many growers find chemical plant growth

retardants to be an effective and inexpensive method of growth control

Many growers find chemical plant growth

retardants to be an effective and inexpensive method of growth control

How do they work?How do they work?

Gibberellin Gibberellin Biosynthesis InhibitorsBiosynthesis Inhibitors

Release of Ethylene Release of Ethylene

Notice branching effectsNotice branching effects

Notice height controlNotice height control

Synergistic effects of two PGRsSynergistic effects of two PGRs

Increasing PGR Effectiveness In Non-responsive Perennials

Additional Benefits:Additional Benefits:

Control production scheduleControl production schedule Increase branchingIncrease branching Induce floweringInduce flowering Drought tolerantDrought tolerant Pollution tolerantPollution tolerant

Additional Benefits:Additional Benefits:

Intensely green foliageIntensely green foliage Resistant to mechanical Resistant to mechanical

damagedamage Protection from some pests Protection from some pests

(whiteflies)(whiteflies) Overall higher quality and Overall higher quality and

aesthetic valueaesthetic value

PGRs for use in Greenhouses:PGRs for use in Greenhouses: B-NineB-Nine

CycocelCycocel BonziBonzi

SumagicSumagic FlorelFlorel A-RestA-Rest

Chemical PGRsChemical PGRs

B-Nine (Daminozide)B-Nine (Daminozide) labeled for annuals and labeled for annuals and

herbaceous perennialsherbaceous perennials low activity (relatively safe)low activity (relatively safe)

Cycocel (Chlormequatchloride)Cycocel (Chlormequatchloride)not labeled on many cropsnot labeled on many cropscauses yellowing above 1500 causes yellowing above 1500

ppmppm

Chemical PGRsChemical PGRs

B-Nine/Cycocel tank mixesB-Nine/Cycocel tank mixesSynergistic combinationSynergistic combinationCycocel 800-1,500 ppmCycocel 800-1,500 ppmB-Nine 800-5,000 ppmB-Nine 800-5,000 ppm

Chemical PGRsChemical PGRs

A-Rest (Ancymidol)A-Rest (Ancymidol)intermediate activityintermediate activitybroad labelbroad label

Chemical PGRsChemical PGRs

Bonzi (Paclobutrazol)Bonzi (Paclobutrazol) broad spectrum labelbroad spectrum label high activityhigh activity

Sumagic (Uniconazole)Sumagic (Uniconazole) broad spectrum labelbroad spectrum label most active PGRmost active PGR

Chemical PGRsChemical PGRs

Florel, Ethrel, Pistill, (Ethephon)Florel, Ethrel, Pistill, (Ethephon)causes plant to release ethylenecauses plant to release ethylenenarrow-spectrum labelnarrow-spectrum label

PGR EfficacyPGR Efficacy

Application timingApplication timingDosageDosageTarget tissueTarget tissue

foliage/stemsfoliage/stemssubstratesubstrate

PGR EfficacyPGR Efficacy

Environmental ConditionsEnvironmental Conditionsenvironment at applicationenvironment at applicationstatus of plantstatus of plantpost-application treatmentpost-application treatment

Application TechniqueApplication Technique

ApplicationApplication

Chemical must be accurately Chemical must be accurately measuredmeasured

ALWAYS wear long sleeves, ALWAYS wear long sleeves, pants, gloves, and shoes with pants, gloves, and shoes with closed toes when mixing and closed toes when mixing and applying PGRs!!!!!!applying PGRs!!!!!!

Media DrenchesMedia Drenchesspecific specific

volume/potvolume/pot

Foliar Sprays Foliar Sprays Specific Specific

volume/area volume/area (0.5gallons/ (0.5gallons/ 100ft100ft22))

PGR overdosePGR overdose Example: Bonzi overdose on Example: Bonzi overdose on

pansiespansies Ways To ReverseWays To Reverse

gibberellins (Pro-Gibb) gibberellins (Pro-Gibb) high-N nutritionhigh-N nutrition

QUESTIONS? QUESTIONS?